United States 

Department of 

Agriculture 

Pacific Northwest 

Research Station 

General Technical 

Report 

PNW-GTR-332 

September 1994 
Technical Editor

Pesticide Precautionary Statement

Pesticides used improperly can be injurious to humans, animals, and plants. Follow

the directions and heed all precautions on the labels.

Store pesticides in original containers under lock and key-out of reach of children

and animals-and away from food and feed.

Apply pesticides so that they do not endanger humans, livestock, crops, beneficial

insects, fish, and wildlife. Do not apply pesticides when there is danger of drift, when

honey bees or other pollinating insects are visiting plants, or in ways that may

contaminate water or leave illegal residues.

Avoid prolonged inhalation of pesticide sprays or dusts; wear protective clothing and

equipment if specified on the container.

If your hands become contaminated with a pesticide, do not eat or drink until you have

washed. In case a pesticide is swallowed or gets in the eyes, follow the first-aid treatment given on the label, and get prompt medical attention. If a pesticide is spilled on

your skin or clothing, remove clothing immediately and wash skin thoroughly.

Do not clean spray equipment or dump excess spray material near ponds, streams, or

wells. Because it is difficult to remove all traces of herbicides from equipment, do not

use the same equipment for insecticides or fungicides that you use for herbicides.

Dispose of empty pesticide containers promptly. Have them buried at a sanitary landfill dump, or crush and bury them in a level, isolated place.

NOTE: Some States have restrictions on the use of certain pesticides. Check your

State and local regulations. Also, because registrations of pesticides are under constant review by the Federal Environmental Protection Agency, consult your county

agricultural agent or State extension specialist to be sure the intended use is still

registered.

HUGH C. BLACK, forest wildlife biologist (retired), was National Program Manager,

Animal Damage Control, U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station, Portland, Oregon, from June 1988 until January 1991.

He worked on this handbook as an independent contractor and as a Forest Service

volunteer.
Animal Damage

Management Handbook

Hugh C. Black, Technical Editor

U.S. Department of Agriculture

Forest Service

Pacific Northwest Research Station

Portland, Oregon

General Technical Report PNW-GTR-332

September 1994
Abstract Black, Hugh C., tech. ed. 1994. Animal damage management handbook. Gen.

Tech. Rep. PNW-GTR-332. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 236 p.

This handbook treats animal damage mangement (ADM) in the West in relation to

forest, range, and recreation resources; predator management is not addressed. It

provides a comprehensive reference of safe, effective, and practical methods for

managing animal damage on National Forest System lands. Supporting information is

included in references after each chapter and in the appendices.

Keywords: Animal damage management, integrated forest protection, wildlife problem

species, damage identification.

CAUTION

Before any control actions are undertaken, be sure to determine the effects they

will have on Threatened, Endangered, and/or Sensitive species. For example. the

use of poison baits for control of pocket gophers in occupied Grizzly Bear habitat

is restricted under a Section 7 consultation with the U.S. Fish and Wildlife Service

Several genera listed in this handbook (Sorex, Eutamias, Thomomys, Microtus,

Neotoma, and Sylvilagus bachmani) have species listed as federal candiates for

review under the Endangered Species Act and may be considered a Sensitive

species by the USDA Forest Service.
Foreword

This handbook is adapted from Forest Service Handbook (FSH) 2609.22, Animal

Damage Control Handbook, Region 6 (Pacific Northwest Region), Amendment No. 6,

September 1988. (FSH 2609.22 was published in 1966, and later revised and

updated several times. It was revised and adapted for use in the Pacific Southwest

and Pacific Northwest Regions in 1976 and for use in the Northern Region in 1988.)

This publication responds to the need for a comprehensive reference for safe, effective, and practical methods for managing animal damage on National Forest System

lands in the West. Emphasis is placed on prevention of damage, preferably by indirect

means, rather than on direct control of wildlife or livestock causing damage. Any technique described here, when adapted to fit local and regional situations, should help to

improve animal damage management (ADM) on National Forest System lands and on

other forest and range lands.

This handbook does not provide guidelines specific to a National Forest System Region or Forest and, thus, may lack the indepth treatment desired by some readers. It

is hoped, however, that the user will find the tools necessary to form a good approach

to specific animal damage problems.

These procedures are guidelines, not prescriptive directions. Successful ADM requires

ingenuity and resourcefulness on the part of the biologist or other resource specialist,

who must assess the need for ADM, use available resources, and adapt procedures

appropriate to site-specific problems. These guidelines also are consistent with the

Forest Service’s emphasis on resource coordination; that is, the effort to have wildlife

biologists work in close consultation with foresters and other resource specialists to

develop approaches to ADM that will successfully limit animal damage and minimize

adverse impacts on desired wildlife and their habitats.

Animal damage management is a dynamic process that is constantly being improved

and expanded by new techniques and refinements of the old. For these reasons, we

encourage users to keep up with the state of the art through the literature and by

other means. We also encourage users to become involved, to share their ideas with

others, as successful practices used in their area may be adapted and used

elsewhere.

Robert D. Nelson

Director of Wildlife, Fish, and Rare Plants
Preface

This handbook focuses on animal damage management (ADM) in relation to forest,

range, and recreation resources; predator management is not addressed. Methods

for limiting animal damage to seedlings, saplings, and mature trees traditionally have

emphasized direct control (baiting, trapping, snaring, and special hunts) of wildlife

problem species and use of physical barriers (plastic-mesh tubing and fencing). But

these practices are limited in effectiveness, costly, and becoming increasingly restricted by regulations and the public’s concerns regarding their use. The potential

impact of direct controls on threatened and endangered species and other nontarget

species and on animal welfare is also of growing concern. In recent years, the value

of indirect methods (based primarily on the modification of silvicultural practices) for

avoiding or minimizing animal damage has become increasingly important. Integrating

direct and indirect methods, in coordination with silvicultural systems, offers the best

approach for managing animal damage. Because silvicultural and range management

practices profoundly influence the susceptibility of developing stands to animal damage, an understanding of these practices is critical to sound, cost-effective ADM on

forest and range lands.

Management of animal damage on National Forest System (NFS) lands is a significant issue for forest resource managers and may become more so in the future. Resource managers must assess the long-term effects of animal damage, the need for

management, the degree of protection needed, if any, and the efficacy and risks associated with specific management practices. Greater emphasis on ecosystem management will require consideration of a broader range of biological and environmental

factors in preparing an integrated program of ADM (see chapter 1). Animal damage

management also is increasingly affected by the social, political, legal, and ethical

environment in the United States (see chapter 1). Societal values must be incorporated in decisionmaking processes for ADM.

“New forestry,” which involves new approaches to forest regeneration and stand and

landscape management, including practices that increase habitat suitability for problem species and other wildlife, also will have a major impact on ADM. Populations of

and damage by mountain beaver and pocket gophers, for example, may increase in

shelterwood stands and other stands harvested under new forestry practices. Greater

reliance on natural regeneration also may renew concerns over the impact of seedeating mammals and birds. New forestry is likely to improve habitat conditions and
increase the potential for damage caused by most of the wildlife species treated in

this handbook. New resource management objectives with greater emphasis on

threatened, endangered, and sensitive species and noncommodity resources, however, may reduce the economic costs assigned to animal damage because of

reduced or delayed timber yields.

Extensive references are given in each chapter of this handbook, especially in

chapter 5, and provide suggested reading for each wildlife species covered. In addition to these sources of information, users should be alert to problem analyses of key

species, such as “Porcupine Control: A Problem Analysis” (see chapter 5) and “Pocket Gophers and Reforestation in the Pacific Northwest: A Problem Analysis” (see

chapter 5). Annotated bibliographies on wildlife problem species also are valuable

sources of information on ADM. Teipner and others (see chapter 5) published a stateof-the-knowledge report on pocket gopher biology, ecology, damage, and control. The

authors reviewed gopher species throughout the United States, and a bibliography

containing more than 1,000 literature citations is included (see chapter 5). “Assessment and Management of Animal Damage in Pacific Northwest Forests: An Annotated

Bibliography” (see chapter 1) is a comprehensive reference guide to published information on ADM in the Pacfic Northwest and other regions. It includes citations and

abstracts from more than 900 papers and is indexed by subject and author.

Supporting information can be found in the references after each chapter and in the

glossary of technical terms. In appendix 3 are reprints of four key papers on “Vexar’

seedling protectors that estimate cost-effectiveness of animal damage control and

give animal damage prediction models and an overview of ADM in the Pacific

Northwest. The appendices also include a sample contract for building a deer fence

and information on gopher-baiting probes and the forest-land burrow builder.

Possibly the most comprehensive reference on ADM is “Prevention and Control of

Wildlife Damage” (see chapter 4). This valuable compendium provides indepth treatment on everything from “armadillos to woodpeckers” and “beavers to weasels.” It

contains detailed sections on supplies and materials and pesticides, including a listing

of all pesticides registered for control of terrestrial vertebrate pests. In addition, it contains the following sections: “Identifying Wildlife Damage,” “Procedures for Evaluating

Predation on Livestock and Wildlife,” and “Wildlife Diseases and Man.” It should be

on the bookshelf in all Districts and Forests.

Wildlife biologists, silviculturists, and pesticide-use specialists (District, Forest, Region)

can provide technical assistance in ADM. Expert assistance is also available from the

USDA Animal and Plant Health Inspection Service; see memorandum of understanding between APHIS-ADC and the USDA Forest Service in appendix 2). Extension wildlife specialists with the Cooperative Extension Service, U.S. Department of

Agriculture, also can provide technical support in ADM. Biologists with the Fish and

Wildlife Service, U.S. Department of the Interior, and those with state wildlife agencies

also may be consulted regarding ADM, particularly if sensitive, threatened, or

endangered species may be involved.

Although we may expect an increased tolerance of animal damage in the future, resource managers are responsible for using the best knowledge available to solve

these problems.

Hugh C. Black

Technical Editor
Contents

1

9

21

35

59

153

157

162

195

214

226

235

Chapter 1: Animal Responses to Habitat Changes

Chapter 2: Damage Identification and Prediction

Chapter 3: Surveys

Chapter 4: Methods for Managing Damage

Chapter 5: Wildlife Problem Species and Their Management

Appendix 1: Common and Scientific Names

Appendix 2: Memorandum of Understanding

Appendix 3: Reprints of Technical Papers

Appendix 4: Deer Fence Contracts-Examples

Appendix 5: Gopher Baiting Probes and Forest-land Burrow Builder

Glossary

Metric Equivalents
Chapter 1:

Animal Responses to

Habitat Changes

Contents 2 Introduction

2 Silvicultural Practices

4 Fuel Management

4 Unburned Fuels

4 Burned Fuels

5 Fuel Piling

5 Wildfire

5 Animal Use

5 Palatability

5 Associated Forage Species

5 Climate, Soil, and Topography

5 Forage Preference

6 Impacts of Use

6 References
Introduction

Silvicultural

Practices

To maintain animal use of forest resources within acceptable levels, resource managers must have a basic understanding of the physiological requirements, general

behavior, and responses of animals to habitat changes. (See McComb and Hansen

[1992] for a comprehensive overview of forest wildlife ecology.) Responses of animals to specific habitat changes are not always well understood. Different animal species often respond differently to similar habitat treatment. Because the system is dynamic, animal damage management must be site specific. No single method of control is universal.

All animals need food, water, shelter, and space. Significant changes in the distribution, relative abundance, or type of food, water, and shelter can influence animal

behavior and cause a change in population density or use of an area by a particular

species. Some species will find an increase in the type of habitat they prefer and will

benefit. Other species will find the habitat they prefer decreased and will be adversely

affected. Changes in numbers and distribution of animals and intensities of plant use

can be expected when land-management activities alter habitats.

Forest trees and their seeds constitute a portion of the natural diet of many forms of

wildlife. For example, feeding on conifers by big game is directly related to animal

preference for particular tree species and to the availability of other preferred foods

at the time. Indirect control by means of habitat manipulation (based primarily on the

modification of silvicultural practices) can be an effective way of limiting animal damage, particularly when combined with other means of animal damage management

(ADM). By making the habitat less suitable for wildlife problem species, the impact on

plantations and older stands often can be reduced or managed more easily by other

means.

One of the best and most comprehensive sources of up-to-date information on the

influence of silvicultural practices on animal damage is Black (1992). This book provides a state-of-the-art assessment of ADM as practiced in the forests of the Pacific

Northwest. It is a compilation of published information and reports based on operational experience. The book’s central focus is the potential of silvicultural practices to

minimize animal damage, but it necessarily includes information on the use of chemical repellents, mechanical barriers, and direct control measures to minimize the

impact of animal damage.

Work with a Forest silviculturist and other specialists to establish an integrated approach to (ADM) that is applicable to the specific site in question.

It is beyond the scope of this book to discuss silvicultural practices in detail, but a

brief overview of basic silvicultural practices is provided.

Silvicultural systems are divided into two principal categories: even-age and unevenage management.’ Within each system are several regeneration methods. Even-age

management includes clearcut, seedtree, and shelterwood regeneration methods.

Uneven-age management uses single tree or group selection and coppice methods

of regeneration.

‘Definitions of terminology are given in the “Glossary” at the

end of this book.

2
Clearcutting removes the canopy and the existing vegetation, thereby allowing succession to begin. Early successional plants occupy the site and change the habitat

from one suitable for animal species associated with mature forest stands to one that

species associated with new plantations will use. Variations in unit size and rotation

length are the principal determinants of the type and extent of wildlife habitat produced. Rodents, hares, rabbits, and other herbivores attracted to the high-quality

successional vegetation frequently damage young conifers.

In areas where pocket gophers occur, for example, use of the shelterwood regeneration method, in place of clearcutting, has created less favorable habitats for gophers

and reduced damage to the developing stands (Emmingham and others 1992).2

Uneven-age management produces a smaller area of disturbance than even-age

management. Forest stand structure remains relatively similar to the preharvest condition. Thus, mature forest wildlife species are favored and damage from such species

as deer, elk, or gophers would be expected to be less prevalent.

Small group selection (l/4- to l/2-acre groups of trees) produces significant amounts

of edge, which may promote increases in deer or elk populations. Shade-tolerant species, such as western hemlock and grand fir, are favored by group selection in the

Douglas-fir region. Both tree species are less desirable forage to browsing animals

than Douglas-fir.

Coppice silviculture is not common in the United States, but it may be used with

sprouting hardwood species such as California black oak, tanoak, and madrone. This

method could alleviate the need for planting (where management objectives favor

maintenance of hardwoods) while producing wildlife forage. Because only a few

sprouts per clump are needed for the future stand, browsing should not be a problem.

When animals search for food their movements are closely related to the availability

and distribution of cover. Small forest openings are usually fully used by big game.

Large openings receive their greatest use near the “edge.” Use of the inner portions

of large openings differs with the amount of escape cover within the opening or that

develops over time.

Big-game carrying capacity increases rapidly as the diversity and volume of lowgrowing vegetation increases after clearcutting or wildfire. This trend may continue for

10 to 20 years after logging, or until tree canopies close and begin to shade out the

understory. Delays in reforestation may extend this period of high forage production.

As tree canopies close, the amount, diversity, and nutritional quality of understory

vegetation decrease and habitat quality declines (for early successional species).

Changes in big-game habitat carrying capacity may be roughly proportional to the

changes in habitat resulting from forest management.

Timber management often improves the quality of big-game habitat, particularly on

winter ranges. As the quality of browse of the harvested area is reduced by successional trends, new areas can be harvested. To maintain productive big-game habitat,

protection from animal damage may be necessary for newly planted young conifers.

‘Scientific names of all species are given in appendix 1

3
The type and quality of wildlife habitat created by timber management is determined

mainly by the systems of timber harvest and fuel management that are used. Clearcutting, and to a lesser extent group-selection cutting, sets back plant succession

and usually results in the temporary production of large quantities of forage. Shelterwood cutting produces similar but smaller increases in big-game carrying capacity

than does clearcutting or group-selection cutting.

Fuel Management Fuel management and planting-site-preparation practices can directly affect use by

wildlife and livestock of treated areas.

Unburned Fuels Rabbits, hares, and many species of rodents are secretive and depend on easily accessible cover for protection from predators. Entire home ranges may exist in small

areas where food and cover are abundant. This is particularly true in areas with accumulated down and dead material. Under these conditions, population density often is

limited only by the space requirements of individual animals.

Burned Fuels

Established populations of rabbits, hares, and rodents may expand, if favorable habitat is provided by unburned fuels. These animals will use any available food, including

tree seeds and seedlings. Unburned fuels may provide some protection for young

trees by restricting movement of big game and cattle and by reducing exposure of

trees. Most of the low, herbaceous, and shrubby vegetation responds quickly to the

increased light and moisture produced by canopy removal. This improved food source

attracts big game and may, in turn, reduce browsing pressure on both natural regeneration and planted trees.

Broadcast burning of logging slash and other fuels creates changes in the availability

of food and cover, which directly affect the composition, distribution, and abundance

of small-mammal populations. Burning also may directly kill some small mammals. In

the Douglas-fir region of Oregon, prescribed burning temporarily reduced populations

of small mammals (Hooven and Black 1976) and, in Washington, populations of

mountain beaver, particularly after an intense burn (Motobu 1978). Animals also may

be affected by minor changes in the microclimate, such as soil-surface temperature,

water penetration, and air movement. In Douglas-fir clearcuttings in Oregon, before

and after logging, Gashwiler (1959) found that deer mice increase after fuel burning,

but chipmunks, hares, and redbacked voles decrease.

Steen (1966) reports significant differences in the development of vegetation on

burned sites compared with unburned sites near Oakridge, Oregon. Plant composition

and the rates of development were affected. Predicting the magnitude of change in

habitat after burning is difficult, however. Pengelly’s (1961) study of broadcast burning

in northern Idaho led him to conclude that “. ..fire is a rough and largely unpredictable

tool due to the following variables: time and intensity of burn, homogeneity of burn,

kind and availability of fuel and seed source, and growing conditions during the first

season after the fire.”

Hot burns tend to favor herbaceous plants and some shrubs, such as red-stem

ceanothus in the Pacific Northwest. Cooler burns tend to favor shrubs present in the

understory at the time of harvest. When increased light and nutrients are available,

these shrubs undergo rapid growth.

Planting immediately after fuel removal has been one of the best ways of minimizing

damage from rabbits, hares, and pocket gophers. Planting larger stock also has

reduced rabbit and hare damage problems in many areas.
Fuel Piling

Wildfire

Animal Use

Palatability

Associated Forage

Species

Climate, Soil, and

Topography

Forage Preference

On many areas, especially those with flat or gentle slopes, fuel often is piled with bulldozers before burning. Treatment leaving 20 to 30 tons of fuel per acre generally is

the recommendation in the Pacific Northwest. This favors regeneration of conifers and

shrubs. Intensive treatments that pile (or remove) all the slash cause plant succession

to revert to an early successional stage. In these stages, grasses and herbs usually

predominate. Intensive site preparation seems to stimulate pocket gopher and vole

activity.

Responses by animal populations to habitat changes after wildfire are similar to those

after broadcast burning of slash. During the revegetation period, wildlife species diversity may be greatest in the successional stage with the greatest diversity of plants.

The degree to which deer and elk and some other animals use a natural burn is influenced (among other factors) by the size and intensity of the burn, abundance of food,

and the proximity of cover.

The basic principles that relate to animal-forage preference may be grouped into five

categories. These are palatability; associated forage species; climate, soil, and topography; forage preference; and impacts of use (Heady 1964). Understanding the

nature of these factors will help land managers recognize and possibly control some

of the complex and interrelated influences governing animal use. A brief summary follows of important elements associated with each of these categories.

Palatability has been defined as a plant characteristic stimulating a selective feeding

response. Some factors found to affect palatability are chemical composition; portion

of leaves, stems, and fruits eaten; plant-growth stage; past grazing use; climate; topography; soil moisture; and soil fertility. Other characteristics possibly related to palatability, such as texture, odor, and external plant form, have received little attention by

biologists.

Availability of choice affects preference. Some plant species growing in one community have been found to have different preference factors than the same species

growing with other combinations of plants. Thus, certain plant species, such as conifers, may be used heavily when sparsely distributed through an area of preferred

forage species.

These factors have been mentioned as affecting palatability, but they probably have

a more important effect by influencing animal behavior. Changes in temperature,

rainfall, soil texture, steepness of slope, and moisture content of foliage often change

animal preferences.

Preferences differ among animal species for plants, parts of plants, or plants at certain growth stages. Animal preference has been related to individual animal conditions

such as fatness, pregnancy, lactation, and hunger. Senses, such as sight, taste,

smell, and touch, coupled with instinct and experience also influence preference. Preferences of individual animals also may differ season to season, day to day, or even

within a day.

5
Impacts of Use

References

Heavy use of forest lands by browsing animals may increase damage to planted

seedlings or natural tree regeneration. The interaction of animals with their habitat has

been demonstrated in the Olympic National Forest in Washington where small study

plots were fenced to exclude deer and elk. The exclusion of browsing animals allowed

low shrubs to develop rapidly. This, in turn, provided excellent cover for rabbits and

rodents. Under these conditions, destruction of Douglas-fir seedlings inside the biggame exclosure by rabbits, mice, and mountain beavers exceeded losses on the outside. Trees were 30 percent taller, on average, outside the exclosures where biggame browsing had reduced small-mammal cover and vegetative competition. Deer

exclosures in the Allegheny National Forest in Pennsylvania also have demonstrated

the deleterious effects of deer browsing on hardwood regeneration (Tilghman 1989).

In other areas, damage to seedlings may not occur even though big game may

browse native shrubs sufficiently to change shrub forms and sizes. This has been

reported by the Umatilla National Forest in Oregon

Moore and Reid (1951) observed that pocket gophers adversely affect plant composition in several ways: favored foods are gradually removed and replaced by those of

lower palatability, soil excavated from runways suppresses plants on which it is deposited, soil mounds are occupied quickly by annuals that usually are less desirable

than the original perennial vegetation, and unused runways provide refuge for other

herbivorous rodents such as deer mice and meadow mice. Gophers also prevent

natural improvement of mountain meadows that are in poor condition, but do not limit

improvement of meadows in fair or better condition.

Uncontrolled grazing by big game or livestock greatly influences soil compaction and

range condition (Graham and others 1992). With time, plant communities may be

completely altered. The more obvious effects are changes in plant composition, density, vigor, soil structure, and the rate of soil erosion. All wildlife species are responsive

to both subtle and dramatic modifications of their habitat. Thus, the type of land use

practiced influences their distribution, density, and diversity.

Asherin, D.A. 1976. Changes in elk use and available browse production on north

Idaho winter ranges following prescribed burning. In: Proceedings, elk-loggingroads symposium; 1975 December 16-17; Moscow, ID. Moscow, ID: University

of Idaho: 122-134.

Black, H., Jr.; Scherzinger, R.J.; Thomas, J.W. 1975. Relationships of Rocky Mountain elk and Rocky Mountain mule deer to timber management in the Blue Mountains of Oregon and Washington. In: Proceedings, elk-logging-roads symposium;

1975 December 16-17; Moscow, ID. Moscow, ID: University of Idaho: 11-31.

Black, H.C., ed. 1969. Proceedings, symposium on wildlife and reforestation in the

Pacific Northwest; 1968 September 12-13; Corvallis, OR. Corvallis, OR: Oregon

State University, School of Forestry. 92 p.

Black, H.C., ed. 1974. Proceedings, symposium on wildlife and forest management

in the Pacific Northwest; 1973 September 11-12; Corvallis, OR. Corvallis, OR:

Oregon State University, School of Forestry, 236 p.

Black, H.C., tech. ed. 1992. Silvicultural approaches to animal damage management

in Pacific Northwest forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Research Station.

422 p.

6
Emmingham, W.H.; Holthausen, R.; Vomocil, M. 1992. Silvicultural systems and

stand management. In: Black, H.C., tech. ed. Silvicultural approaches to animal

damage management in Pacific Northwest forests. Gen. Tech. Rep.

PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station: 123-142. Chapter 6.

Gashwiler, J.S. 1959. Small mammal study in west-central Oregon. Journal of

Mammalogy. 40( 1): 128-l38.

Graham, R.T.; Kingery, J.L.; Volland, L.A. 1992. Livestock and forest management

interactions. In: Black, H.C., tech. ed. Silvicultural approaches to animal damage

management in Pacific Northwest forests. Gen. Tech. Rep. PNW-GTR-287.

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Research Station: 351-364. Chapter 17.

Hagar, D.C. 1960. The interrelationships of logging, birds, and timber regeneration in

the Douglas-fir region of northwestern California. Ecology. 41(1): 116-125.

Hanley, T.A.; Bunnell, F.L.; Starkey, E.E. 1984. Habitat relationships of Cervidae

(deer) in old-growth forests. Proceedings, The Society of American Foresters; 1983

October; Portland, OR. [Location of publisher unknown]: [Society of American

Foresters]: 361-367.

Heady, H.F. 1964. Palatability of herbage and animal preference. Journal of Range

Management. 17(2): 18-20.

Hooven, E.F.; Black, H.C. 1976. Effects of some clearcutting practices on smallanimal populations in western Oregon. Northwest Science. 50(4): 189-208.

Irwin, L.L. 1975. Effects of intensive silviculture on big game forage sources in northern Idaho. In: Proceedings, elk-logging-roads symposium; 1975 December 16-17;

Moscow, ID. Moscow, ID: University of Idaho: 135-142.

Lawrence, W.H. 1967. Effects of vegetation management on wildlife. In: Proceedings, symposium on herbicides and vegetation management in forests, ranges,

and non-crop lands; [dates of meeting unknown]; Corvallis, OR. Corvallis, OR:

Oregon State University: 88-93.

Loucks, D.M.; Black, H.C.; Roush, M.L.; Radosevich, S.M., tech. coords. 1990.

Assessment and management of animal damage in Pacific Northwest forests: an

annotated biobliography. Gen. Tech. Rep. PNW-GTR-262. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Research Station.

371 p.

McComb, W.C.; Hansen, A.J. 1992. An introduction to wildlife ecology. In: Black,

H.C., tech. ed. Silvicultural approaches to animal damage management in Pacific

Northwest forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 93-122.

Chapter 5.

Moore, A.W.; Reid, E.H. 1951. The Dalles pocket gopher and its influence on forage

production of Oregon mountain meadows. Circ. 884. Washington, DC: U.S. Department of Agriculture. 36 p.

Motobu, D.A. 1978. Effects of controlled slash burning on the mountain beaver

(Aplodontia rufa rufa). Northwest Science. 52(2): 92-99.

7
Owston, P.W.; Smith, S.P.; Stein, W.I. 1992. Stand establishment. In: Black, H.C.,

tech. ed. Silvicultural approaches to animal damage management in Pacific Northwest forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department

of Agriculture, Forest Service, Pacific Northwest Research Station: 143-165.

Chapter 7.

Pengelly, W.L. 1961. Ecological effects of slash-disposal fires on the Coeur d’Alene

National Forest, Idaho. Missoula, MT: U.S. Department of Agriculture, Forest

Service, Northern Region.

Schmidt, R.H.; Brooks, D.L.; Salmon, T.P. 1992. Social, political, legal, and ethical

aspects of animal damage management. In: Black, H.C., tech. ed. Silvicultural approaches to animal damage management in Pacific Northwest forests. Gen. Tech.

Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station: 395-404. Chapter 20.

Steen, H.K. 1966. Vegetation following slash fires in one western Oregon locality.

Northwest Science. 40(3): 113-120.

Tilghman, N.G. 1989. Impacts of white-tailed deer on forest regeneration in northwestern Pennsylvania. Journal of Wildlife Management. 53(3): 524-532.

Walstad, J.D.; Norris, L.A. 1992. Animal damage management in the context of

integrated forest protection. In: Black, H.C., tech. ed. Silvicultural approaches to

animal damage management in Pacific Northwest forests. Gen. Tech. Rep.

PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station: 57-66. Chapter 3.

8
Chapter 2:

Damage ldentification and

Prediction

Contents 10

10

11

12

14

15

15

15

17

20

Introduction

Types of Damage Caused by Wildlife

Damage to Trees

Damage to Rangelands

Soil Compaction

Soil Erosion

Damage to Buildings and Grounds

Prediction of Animal Damage

Key to Wildlife Injuries to Trees

References

9
Introduction Wildlife-caused tree injury, primarily associated with feeding activity, is the result of

removal of some portion of a tree, such as foliage, bark, or roots, that can result in

growth suppression or destruction of the tree. Every injury does not cause economic

loss, and trees may sustain repeated feeding injuries with little or no long-term effect.

Excessive feeding by wildlife on seeds, seedlings, or saplings, however, can prevent

or delay successful reforestation, or it may degrade or destroy valuable crop trees in

maturing stands. Animal damage, in simplest terms, is the result of any kind of animal

activity that interferes with management goals or objectives. (In the past, the emphasis was on animal activity that causes economic losses by reducing or delaying forest

yield.) Assessing the significance of animal damage, however, depends on the resource management objectives for a particular area.

Correct identification of damage is necessary before sound prescriptions can be made

for managing damage. First, determine whether the damage is caused by environmental factors, disease, mammals, birds, insects, or a combination of these agents.

If the evidence indicates that an animal is causing the damage, the species must be

determined.

Identification of animal damage often requires a thorough search for evidence. The

feeding characteristics of some animals are so similar that identification is almost

impossible without evidence such as droppings, hair, tracks, trails, or the presence of

burrows in the area. For example, ants may girdle stems of seedlings just above the

root collar to nurture aphid colonies, grasshopper feeding on needles can be confused

with bird clipping, bird perching sometimes breaks terminal leaders, and terminal

shoots may be damaged by snow or ice. This damage can be confused with mammal

damage unless investigations are thorough. In some instances, it may be necessary

to trap animals, build exclosures, or install cages to identify the damage-causing

agent. Requisites for proper identification of animal damage include an inquisitive and

open mind, a desire to do a thorough job, a knowledge of animals and their habits,

and an ability to interpret field observations.

Types of Damage

Caused by Wildlife

An excellent field guide on this topic for the Pacific Northwest is Lawrence and others

(1961); a dichotomous key to wildlife injuries to trees, adapted from this guide, is included at the end of this chapter. Another useful guide applicable to this same region

is Harestad and others (1986). A related publication by Byrd (1981) describes and

depicts, with excellent color photographs, observable signs and activities of selected

wildlife species, including the identification of wildlife feeding injuries.

Training is necessary to ensure accurate identification of animal damage. The Animal

Damage Control Program of the USDA Animal and Plant Health Inspection Service

(APHIS-ADC) has qualified biologists who can provide this training. Extension wildlife

specialists, USDA Cooperative Extension Service, also may assist with this training.

A wide variety of damage by wildlife occurs on forests, rangelands, and associated

areas. Damage can be grouped into categories by the location where it occurs: forest

lands, rangelands, and buildings and grounds.

10
Damage to Trees Excellent summaries of wildlife damage to forests in the United States and Canada,

with extensive bibliographies, are available (Borrecco and Black 1990, Crouch 1977).

Animals may damage trees in many ways. They clip and browse foliage and leaders,

gnaw and girdle stems and tree boles, inflict trampling injuries, and completely remove tree seedlings. Keys have been developed to identify damage (table 1). Missing trees are a major problem, however. Missing trees near gopher activity logically

can be attributed to gophers; however, when elk and deer pull trees, they often leave

no evidence. Unless there are staked rows of trees in the area, this type of damage

may be missed completely.

To identify damage to trees and shrubs, the characteristic differences between

browsing and clipping need to be recognized.

Browsing-Browsing refers to the feeding habits of ungulates, including deer, elk,

and livestock. Browsing on woody vegetation during the dormant season leaves a

ragged, splintered break (fig. 1), because these animals lack upper incisors.

Clipping-Clipping refers to the feeding habits of rodents and rabbits, which produce

a smooth, oblique cut on woody shoots (fig. 1). These animals possess prominent

chisellike incisors and must tilt their heads to the side to clip a stem.

Table l-Comparative widths of incisor teeth of some

common gnawing mammalsa

Common name Average width of incisor

Inch

Beaver 0.24

Porcupine .14

Black-tailed jackrabbit .10

Snowshoe hare .09

Cottontail rabbit .09

Pocket gopher .06

Western gray squirrel .06

Dusky-footed woodrat .06

Meadow vole .04

Red squirrel .04

Red-backed vole .03

Deer mouse .02

a

 Based on measurements of 6 or more adult specimens of each species

from the museum of Natural History, Oregon State University, Corvallis.

11


Soil Compaction

Figure 3--Pocket gopher mound, showing

typical fan-shaped appearance, and earthen

plug in lower right center.

Figure 4-Pocket gopher snow casts,

showing typical tubular cylinders of

packed soil and occasional overlaying

of the casts.

Figure 5-Mole tunnel showing typical

shallow ridge formed when feeding occurs

near the soil surface.

Figure 6-Mole mound, showing lumpy l

volcanolike appearance. I

I

Rabbits and hares-Signs of rabbits feeding on grasses or forbs are difficult to

distinguish from those of rodents, but fecal droppings are distinctive. As with rodents,

identification of rabbit and hare damage must rely on indirect signs that indicate the

presence or abundance of animals in an area. Pellet group counts are a useful means

of determining presence of rabbits and hares.

Soil compaction can occur when excessive numbers of big game or domestic livestock use areas of heavy, clay soils saturated with moisture, or as a result of harvest

methods.

Areas damaged by compaction look dimpled and animal hoof prints are discernible, if

the trampling is recent. When compaction is severe and prolonged, plant density is

reduced, perennial plants are replaced by annuals, water infiltration is inhibited, and

overland water flow is increased. The area thus is subject to greater wind and water

erosion. Areas along waterways and around meadows are particularly susceptible to

damage by compaction. Sites used by animals in the early spring that have shallow

soils or poor drainage also may be heavily damaged.

14
Soil Erosion

Damage to Buildings

and Grounds

Soil erosion may be initiated by burrowing animals, including pocket gophers, moles,

ground squirrels, badgers, and meadow voles. In some instances, burrows are oriented downslope and serve as small conduits for water from melting snow or heavy

rains. This type of damage is observed in the spring when snow is melting. Later in

the summer, drying, settling, wind action, and animal use obliterate much of the evidence related to the initial cause of the damage. (Field signs of voles, ground

squirrels, gophers, and moles are described in the previous section.)

Various birds and mammals may occupy buildings, adjacent grounds, campgrounds,

and other areas of human activity where they may be a nuisance or hazard to human

health. Animal use of Forest Service buildings and the grounds around them often

leads to excessive maintenance costs. Frequently, little actual damage is done, but

the nuisance problems may warrant removing or discouraging these animals (see

chapter 5).

Birds-Cavity nesters, such as sparrows, starlings, and swallows, often use open air

vents, spaces around utility openings, and other spaces for nest-construction sites.

Rodents-Gnawing occurs wherever rodents are present.

Porcupine-Porcupines are the largest gnawing animals found around buildings.

They have a definite liking for glue in plywood. Such items as work gloves, saddles

and other leather goods, and tool handles are especially attractive. Droppings 1 inch

long are characteristic of porcupines.

Woodrats-Sometimes referred to as pack rats, these native species characteristically build large, bulky stick-nests or houses in the crowns of trees and in sheltered

sites at ground level. The dusky-footed woodrat is a semiarboreal species, whereas

the bushy-tailed woodrat is less arboreal and usually found near abandoned buildings

and rocky outcroppings (Lawrence and others 1961). Both species may cause problems in buildings by fouling stored materials and food supplies. (The dusky-footed

woodrat may also cause minor damage to young conifer stands.) Droppings about

one-third of an inch long are characteristic of woodrat presence.

Mice-Deer mice are abundant on forest lands and frequently move into buildings,

particularly during cold weather. Small holes l/2 inch or less in diameter allow mice to

enter. Droppings about one-eighth of an inch long, chewed paper, and seed hulls are

signs of mouse activity.

Tree squirrels-Tree squirrels, such as red squirrels, occasionally move into buildings or cone-storage facilities. Their presence can be determined by their daytime

activity, food-storage habits, and midden piles of pine cone parts that have been discarded as the squirrel removes the seeds from cones during feeding.

Prediction of Animal In recent years, attempts have been made to predict the occurrence of animal damDamage age in plantations. This reduces treatment costs, because controls are begun only

when necessary. Most such efforts have attempted to relate habitat characteristics to

animal population dynamics, then use localized experience to predict probable damage to plantations for similar conditions. Results occasionally have been useful, particularly when predictions were based on the combined inputs of interdisciplinary

teams composed of foresters, range conservationists, and wildlife biologists. Animal

damage prediction models are being used and refined in Pacific Northwest forests

(see appendix 3).

15
McComb (1992) reviews the types of models appropriate for animal damage management and provides a useful list of references on modeling. He outlines the basic steps

for developing an “expert” model that relates existing habitat conditions to the habitat

preferences of the wildlife problem species. Once these relations are developed and

analyzed, appropriate action plans can be formulated for situations identified as being

at high risk from animal damage. Sophisticated ADM models can be used to predict

the occurrence of animal damage over time.

Districts and Forests should develop ADM models applicable to local conditions; they

are a promising new way to avoid unnecessary treatments. Where animal damage is

expected or predicted, the cost-effectiveness of controlling the damage should be

estimated (see appendix 3).

16
Key to Wildlife This dichotomous key to wildlife injuries to trees is adapted from Lawrence and

Injuries to Trees others (1961).

INJURIES TO SEEDLINGS AND SAPLINGS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A

INJURIES TO MATURE TREES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B

A. INJURIES TO SEEDLINGS AND SAPLINGS

Key

1A. ROOT CLIPPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . . . . 2

1B. STEM BARKING OR STEM BROKEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1C. FOLIAGE CLIPPING AND BROWSING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2. Roots gnawed or clipped at root collar...injured seedling may be tipped

over or partially pulled underground . . . . . . . . . . . . . . . . . POCKET GOPHER

3. Barking on upper stem of saplings or large seedlings . . . . . . . . . . . . . . . . 4

3. Barking basal on saplings or seedlings. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4. Bark abraded and shredded on upper stem; small lateral branches

broken by antler polishing . . . . . . . . . . . . . . . . . . . . . . . . . . . BIG GAME

4. Bark not abraded...lateral branches intact...bark stripped or gnawed

from bole or upper branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5. Barking by gnawing...primarily on pines or hemlocks . . PORCUPINE

5. Barking by means other than gnawing...bark stripped from

terminal and lateral shoots...branch tips browsed . . . . . . . BIG GAME

6. Bark stripped from base of saplings...vertical grooves present on exposed

sapwood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6. Bark not stripped but gnawed from base of saplings or seedlings...lacks

vertical grooves, but many tooth marks on exposed sapwood . . . . . . . . . . . . . . . 8

6. Bark stripped or stem broken by trampling; no grooves or gnawing

apparent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..BIGGAME

7a. Strips of discarded bark at base of tree...vettical grooves on

exposedsapwood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BEAR

7b. Strips of discarded bark absent...irregular vertical claw marks and scattered

horizontal or diagonal tooth marks on exposed sapwood...numerous burrow

entrances in area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MOUNTAIN BEAVER

8. Individual tooth marks less than 1/16 inch wide...gnawed surface

of sapwood fuzzy and roughened...grassy areas with numerous

surface runways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MEADOW VOLE

8. Tooth marks distinct, 1/16 inch wide or wider...surface of exposed

sapwood not fuzzy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

9. Tooth marks 1/16 inch wide...sapwood deeply gnawed...above

ground damage visible immediately after snow melt...soil mounds,

soil casts, and burrow openings . . . . . . . . . . . . . . . POCKET GOPHER

17
9. Tooth marks 1/8 inch wide or wider; sapwood deeply gnawed;

1/2- to l-inch oblong droppings and quills; pieces of outer bark

around base of tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PORCUPINE

10. Bud and needle clipping on terminal or

lateral shoots . . . . . . . . . . . . . . . . . . . . . . . . GROUSE, GROSBEAKS

10. No bud or needle clipping, but with cutting or browsing on terminal

or lateral shoots ...................................... 11

11. Clipping or cutting injuries .......................................... 13

11. No clipping or cutting; browsing injuries only ........................... 12

12. Game trails, droppings and tracks . . . . . . . . . . . . . . . . . . . . . . . . . BIG GAME

12. Browsing-like injury with bud or needle clipping

clustered droppings on stumps, logs and rocks . . . . . . . . . . . . . . . GROUSE

13. Individual tooth marks distinct...clipped stems usually larger than

1/4 inch in diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

13. Individual tooth marks indistinct...clipped stems 1/4 inch or less in

diameter...if on newly germinated seedlings, field signs of rodents are

needed to distinguish from bird or insect injury . . . . . . . . . . . . . . . . . . . 15

14a. Dams, ponds, and lodges present...cutting areas with distinct trails

leading to water..freshly peeled sticks; signs of active beaver

pond...wood chips present near stumps . . . . . . . . . . . . . . .BEAVER

14b. On larger seedlings and saplings, cutting of branches

leaves short stubs on main stem...piles of fresh leafy cuttings

at entrances of numerous burrows . . . . . . . . MOUNTAIN BEAVER

15a. Clipped stems and cotyledons of newly germinated

seedlings, in addition to seed eating . . . . . . . . DEER MOUSE

15b. Clipped newly germinated seedlings...in ponderosa pine region

and mixed conifer region...numerous burrow openings are

signs of ground squirrels

. . . . . . . . . . . . . . . . . . . . . . . . CHIPMUNKS, GROUND SQUIRRELS

15c. Barked stems of larger seedlings, also clipped lateral and

terminal shoots of small seedlings...surface runways in grassy

areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MEADOW VOLE

15d. Flattened ovoid droppings

. . . . . . . . . . . . . . . . . . . . . . . SNOWSHOE HARE OR COTTONTAIL

15e. Clipped seedlings with an oblique cut characteristic of

rodents, but it usually can be distinquished from clipping by

other animals because of the multiple cuts, which leaves a

serrated cut-end. Numerous burrow entrances in area ...

limited to coastal Douglas-fir region . . . MOUNTAIN BEAVER

15f. Clipped, small coniferous seedlings . . . . . . . . . . . PORCUPINE

18
B. INJURIES TO MATURE TREES

16A. TREE CUTTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

16B. BOLE BARKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . 18

16C. BRANCH AND TWIG CUTTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

17. Conical top on stumps, with prominent toothmarks . . . . , . . . . . . . . BEAVER

18. Basal injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

18. Crown injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

19. Long, prominent, vertical grooves on exposed sapwood...large

strips of discarded bark at base of tree . . . . . . . . . . . . . . . . BEAR

19. Vertical grooves and strips of discarded bark lacking...horizontal or

diagonal tooth marks. . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

20a. Gnawing, with distinct horizontal or diagonal toothmarks;

tooth marks 1/8 inch wide or wider . . . . . . . . . PORCUPINE

20b. Gnawing, with tooth marks 1/16 inch wide...Barking

occurs in irregular patterns on lower 7 feet

of tree . . . . . . . . . . . . . . . . . . . . . . . . . . . POCKET GOPHER

20c. Gnawing indistinct...occasional vertical claw marks where

bark has been gnawed from bole...numerous burrow

entrances in area...limited to coastal

Douglas-fir region . . . . . . . . . . . . . . . . .MOUNTAIN BEAVER

21. Long, prominent, vertical grooves on exposed sapwood of upper bole...large

strips of discarded bark at base of tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . BEAR

21. Vertical grooves and strips of discarded bark lacking...prominent horizontal or

diagonal tooth marks or gnawing on sapwood . . . . . . . . . . . . . . . . . . . . . . . . . . 22

22. Prominent horizontal or diagonal toothmarks on exposed sapwood of upper

bole and major branches...oblong droppings up to 1 inch long under tree

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PORCUPINE

22. Prominent tooth marks lacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

23. Short strips of discarded bark (1/2 inch wide by 2 to 3 inches long) under

injured tree...fine gnawing visible on exposed sapwood

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TREE SQUIRREL

23. Short strips of bark absent...large, bulky, stick nests, either in crowns of

trees or on ground in vicinity of injured trees...barking occurs in dense

stands of young conifers . . . . . . . . . . . . . DUSKY-FOOTED WOODRAT

24. Cutting confined to branch tips and twigs...peeled or debudded shoots

litter ground under tree . . . . . . . . . . . . . . . . . . . . . .TREE SQUIRREL

24. Cutting of moderate-sized branches...no peeled twigs

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PORCUPINE

19
References Bailey, V. 1936. The mammals and life zones of Oregon. North American Fauna. 55.

416 p.

Borrecco, J.F.; Black, H.C. 1990. Animal damage problems and control activities on

National Forest System lands. In: Davis, L.R.; Marsh, R.E.; Beadle, D.E., eds.

Proceedings, 14th vertebrate pest conference; 1990 March 6-8; Sacramento, CA.

Davis, CA: University of California: 192-I98.

Burt, W.H.; Grossenheider, R.P. 1964. A field guide to the mammals: field marks of

all species found north of the Mexican boundary. 2d ed. Boston, MA: Houghton

Mifflin Co. 284 p.

Byrd, N.A. 1981. A forester’s guide to observing wildlife use, of forest habitat in the

South. For. Rep. SA-FR 15. Atlanta, GA: U.S. Department of Agriculture, Forest

Service, State and Private Forestry, Southeastern Area. 36 p.

Crouch, G. 1977. Wild animal damage to forests in the United States and Canada.

In: Proceedings. XVI IUFRO World Congress; 1976; [city unknown], Norway.

[Location of publisher unknown]: [Publisher unknown]: 468-475. Reproduced by:

U.S. Department of Agriculture, Forest Service, Alaska Region, Juneau, AK.

Dalquest, W.W. 1948. Mammals of Washington. Publication 2. Lawrence, KS:

University of Kansas, Museum of Natural History. 444 p.

Harestad, A.S.; Bunnell, F.L.; Sullivan, T.P.; Andrusiak, L. 1986. Key to injury of

conifer trees by wildlife in British Columbia. WHR-23. Victoria, BC: Ministry of

Forestry, Research Branch. 38 p.

Ingles, L.G. 1955. Mammals of the Pacific States; California, Oregon, and

Washington. Palo Alto, CA: Stanford University Press. 605 p.

Larrison, E.J. 1970. Washington mammals, their habits, identification, and distribution. Seattle, WA: The Seattle Audubon Society. 243 p.

Lawrence, W-H.; Kverno, N.B.; Hartwell, M.D. 1961. Guide to wildlife feeding

injuries on conifers in the Pacific Northwest. Portland, OR: Western Forestry and

Conservation Association. 44 p.

Marsh, R.E.; Salmon, T.P.; Howard, W.E. 1981. Integrated management of rodents

and other wildlife in campgrounds. San Francisco, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Region. 126 p.

McComb, W.C. 1992. Modeling systems for prescription development. In: Black, H.C.,

tech. ed. Silvicultural approaches to animal damage management in Pacific

Northwest forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 377-393.

Chapter 19.

Pank, L.R. 1974. A bibliography on seed-eating mammals and birds that affect forest

regeneration. Spec. Sci. Rep., Wildl. 174. Washington, DC: U.S. Department of the

Interior, Fish and Wildlife Service, Bureau of Sports Fisheries and Wildlife. 328 p.

20
Chapter 3:

rveys

Contents 22 Introduction

22 Animal-Use Surveys

22 Stocking Surveys

22 Animal Population Surveys

23 Direct Population Estimates

23 Trapline Transects

29 Indirect Population Estimates

29 Counting Animal Signs

30 Seed-Spot Surveys

30 Procedures

34 References

21
I Introduction Two principal types of surveys are used to assess animal impacts on forest and

range resources. The first measures the extent of the physical use of trees and other

plants and is called an “animal-use survey.” The second measures animal numbers

and is called an “animal population survey.” When possible, animal damage surveys

should be included as part of other surveys, such as stocking or range surveys.

(Techniques for measuring use of forage plants are described in FSM 2210 and

2620.)

Animal-Use Surveys Surveys are made on areas scheduled for reforestation, on areas where animal use

is delaying or preventing establishment of tree plantations, and on other areas where

animal damage is a real or potential problem. These surveys are used to:

. Locate animal use or damage areas.

Stocking Surveys

. Identify animals causing a damage problem.

. Measure animal use.

l Provide data needed for control or prevention of damage.

. Predict in advance of reforestation where animal use or damage is likely to occur.

. Evaluate the impact of animal use on reforested areas.

l Survey predator dependence on rodents, especially raptors that may be

impacted by secondary poisoning.

Survey procedures are designed to furnish District Rangers and other resource managers with reliable information to determine where and when animal damage management is needed.

Stocking survey procedures described in Regional reforestation handbooks are designed to evaluate reforestation efforts. These procedures include methods for measuring tree stocking in relation to the influence of weather, vegetation, animals, insects,

and diseases. Some forms for reforestation stocking surveys also are designed to

allow collection of information on the effects of animal damage. Marking trees with

stakes in rows or plots is the best way to determine whether trees are missing and

aid in the identification of damage agents.

Examination of staked seedlings provides only an index to survival and growth of

seedlings on a unit, however, unless all the seedlings on samplings plots or the entire

unit are staked. Staking a small number of trees does not provide precise information

on stocking, spacing, distribution of trees, or damage. But it is a useful means of

measuring the effects of specific injuries by animals or other factors on growth and

survival of seedlings over time.

Examples of potential animal damage areas are south slopes, winter ranges, habitat

types particularly favorable to activity by the damaging animal(s), and plantings on

established brushfields or grassy areas.

Animal Population

Surveys

Two general types of population surveys are counts by direct observation of animals,

and indirect estimates of populations by counting pellets, mounds, tracks, or other

indicators of animal presence. Variations in terrain, aspect, slope, cover, and animal

distribution, abundance, and habits require that techniques be selected to best fit

local conditions.

22
Estimating total populations from sampling surveys is extremely difficult. Population

recruitment, mortality, trap shyness, mobility, sex, and age composition are only a

few of the many variables that must be identified and interpreted in making accurate

estimates of population size. This type of estimation requires good sampling design

and ample time to collect data.

Survey procedures must be adequate for obtaining the data needed, but they should

be as simple and efficient as possible. Emphasis is placed on measuring one or

more of the following parameters:

l Species of animals inhabiting an area.

. Population trends.

Direct Population

Estimates

l Relative abundance of animals in an area.

l Patterns of animal distribution.

. Effectiveness of control programs.

l Sex and age composition of animal populations.

Direct population estimates are used most frequently to determine population trends,

measure catch per unit of effort, and estimate population size. Big-game populations,

for example, often are estimated by trend counts, which survey a given area or route

to develop a population index. Trend counts yield an index to estimate population size

based on periodic counts, occurrence of damage, or catch per unit of effort. Use care

when interpreting trend counts, because weather and other factors frequently influence the number of animals seen.

Trapline Transects This is an inexpensive method of obtaining useful data on small-mammal populations.

Check with local wildlife officials to determine whether restrictions apply.

Kill-trapping-Traplines may be run at any time of the year when animals are active.

The periods of inactivity, including hibernation and aestivation, need to be determined

locally.

Comparisons of population levels before and after baiting are most reliable when

sampling techniques are standardized. Attention to the following details will help

achieve uniformity:

. Use the same type and size of traps.

l Maintain consistent spacing between traps.

l Use the same type of bait.

l Tend traps at the same time of day and in the same manner each day.

l Conduct trapping under similar weather conditions, if possible.

Equipment needed--

l Museum special snaptraps, 25 for each trapline. Allow several extra traps for replacement. Ordinary mousetraps may be used, but they are too small to catch

chipmunks.

. Bait consisting of equal amounts of peanut butter and whole rolled oats.

l Compass to orient trapline and relocate traps.

23
. Plastic flagging to mark trap locations.

l Painted stakes to identify trap stations, when permanent locations are needed.

. Forms for recording results (the same form may be used for both snaptrap and

live-trap surveys; figs. 7 and 8).

Procedures

l Set traps in a straight line at intervals of either 1/2 or 1 chain (66 feet). One-half

chain spacing should be used if mammals having small home ranges, such as

voles and shrews, are of primary interest. One-chain spacing should be used for

chipmunks and ground squirrels.

l Secure traps to a stake or heavy object by wire or chain. This will prevent poorly

caught animals from dragging traps away, or predators from moving the traps.

l Allow a minimum of 5 chains between traplines, when more than one line is

needed. In small areas, it may be necessary to locate stations in one direction,

offset the line by 5 chains, and continue the line back and forth, as needed, to

complete the trapline.

As the size of the area increases, it is impractical to locate trapline transects with the

same intensity as for smaller areas; therefore, the following sampling intensity is

recommended:

O-100 acres 1 transect/50 acres

100-1,000 acres 1 transect/100 acres

1,OOO-3,000 acres 1 transect/200 acres

3,000-6,000 acres 1 transect/500 acres

l Mark trap locations either by fastening plastic flagging to vegetation or other

objects, or by driving painted stakes at each trap station. The latter method will

permit accurate trap placement when retrapping.

l Record compass direction of each trapline on a data sheet.

. Sample representative habitat by placing traps next to logs, stumps, shrubs, or

grass clumps within 5 feet of each trap station. Prepare a flat spot, 8 inches in

diameter, for each trap to ensure that traps rest firmly on the ground and are not

tilted. Traps set during rainy weather should be protected from direct rain impact,

to prevent bait from washing from the trigger. Protection may be obtained by

setting traps under logs, bark, or similar cover; leave enough space above the

trap to allow it to spring shut. For voles, set the trap axis perpendicular to the

runway, so that the vole trips the trigger when using the runway.

. Bait and set each trap by pressing a pinch of bait firmly onto the trigger. Expose

traps on 3 successive nights; check them each day at about the same time as

originally set, remove dead animals and record capture location, species, and

other pertinent data. Rebait and set traps after each examination. Trapping may

be discontinued after the first or second night, if the catch of seed-eating mammals exceeds five per trapline. This would indicate a population high enough to

consume most of the untreated seed, if direct seeding were planned.

24
Small-Mammal Snaptrap Survey

0bserver:JJones

Forest: Idaho Panhandle District: Avery Date: 10/1/77

Location: T 26 N; R19E; Sec. 4; NE1/4; Big Burn Line No.: 1

Size of Area: 67 acres Percent Slope: 10-30 Aspect: NE Elevation: 2800'

Weather First Day: Clear calm, High temp 80+ - Low temp approx 45 deg. F

Weather Second Day: Clear 10-20 mph wind - approx, temp high 70, low 40 deg F

Weather Third Day: Partly cloudy, no rain, light breeze, high 70, low 40

Ground Cover: Mainly burned logs, some spots of unburned grass and low shrubs

Area History: Area logged 1978. Wildfire through area on 9/27/68

Sta.

No.

P

P

P

P

P

P

G

P

P

G

P

P

P

G

P

P

P

Sp. D No. 4 SP D

sp. c No. 3 sp. c

Sp. GS No. 1.

sp.- No. sp.-

sp.- No. sp.-

‘otal

:atch No . - 8 No. 4

RI-FS-2650-1 (3/87)

Figure 7-Sample small-mammal sample survey form (front).

25
Instructions

Observer, Forest, District, Date: self-explanatory.

Location: Give legal or local description.

Line number: To identify lines when more than one is used.

Size of area, slope, aspect, elevation: Self-explanatory.

Weather: List approximate high and low temperatures, wind conditions, precipitation,

and cloud cover conditions during each trapping day.

Ground cover: List dominant vegetation type and density if vegetation is present in

the area. If a recent burn, list as such.

Area history: List management practices or abrupt natural changes that have taken

place on the area.

Station number: Be sure to read stations in the same sequence each time, to

facilitate comparisons among trapping days and trapping periods.

Trap condition: the following code is usedN = not sprung; S = sprung; M = trap missing

Bait condition: the following code is usedP = bait present; G = bait gone

Species caught: the following code is usedD = deer mouse; C = chipmunk; M = meadow vole; S = shrew;

GS = golden-mantled ground squirrel; and 0 = other (list by species).

If a species is recaptured (live-trapping), place an “R” in the species caught column.

Total catch by species and number for each day.

Total combined catch for each day.

Grand total: species and combined catch for the 3-day period.

Map: Use the space below to show the trapline pattern in relation to the sample area.

. ..\.\........&..W. . . . . . . . . . . ...!. . . .

. . . . ..“..“.........‘..“‘....

. .

. . . . . . . . . . . . 2

. .

. . . .

: . . . .

. . . . .

. . . . . . . . . . . . . . . . . . . . . . . .

. . . .

. -

. . : : .

. . . . .

.*.&.d.i . . . . i . ..‘..“.:..“:....:....:

. . . . , . $‘& c’: : : : : . . . . . . . . . . ,.... . . . . . . . . . . . . . . . . . . . . . . . . . . .

, . . . . . .

. . . .

..+.i ; i i ;

. . . . . . . . .

. ,; . .~ . . : . . . . : . . . . : .\‘_

:Q :

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. . . . . . . . . . . .‘?si . . . .+. \

fi . .

. . .*. .

-

. . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . 0. . . .

. . . . . . . . . . i...

. . : . . . . . . . . . . . _.....................

. . . .

. .

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r......... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. .

. .

. .

. . . . . . . . .

. .

. .

. . . .

. . . . .

. . .

. . . . . . . . . . . . . . . . . . . . . . . .

. . . . .

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. . . . .

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.

......

. ..\w . . . . . . . . . i . . . . . . . . . . . ..‘................

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. . . : . .

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.............................. . .

\

.......

...........

. .....

. :. .

...................

:

. .

.

.......

.......

: .... : : :

.......

.......

.................................

. ...................................

Figure 8-Sample small-mammal census form (back).

26
. Because snaptraps remove animals from the population, retrapping in the same

area may yield misleading data. This source of error can be overcome by either

relocating subsequent traplines 5 or more chains away from the original line or

waiting 1 year to resample the area.

. Summarize data by expressing the catch as numbers of animals caught per

100 trapnights, so that the results of all surveys can be compared, regardless

of the number of traps used. One trapnight is defined as one trap set for 1 night.

With two standard traplines, totaling 50 traps, the first night of trapping is equal

to 50 trapnights. Three nights of trapping would equal 150 trapnights. The

formula for expressing catch per 100 trapnights is:

total catch of small mammals

(no. of traps) x (no. of trapnights)I

x 100 = small mammals caught per 100 trapnights

If two traplines, with a total of 50 traps, were run for 3 nights, and 15 small mammals

were caught, trapping success would be calculated as follows:

15 [ 1(50) (3)

x 100=1,500 = 10 small mammals caught per 100 trapnights.

Many environmental variables influence trapping success. For example, 75 traps

placed for 1 night in heavy rain might yield different results than 25 traps set for

3 nights in clear weather, even though the number of trapnights is the same.

Lengthening the trapping period tends to minimize daily variations and provides

more reliable data.

interpreting results-Many environmental conditions affect the rate and composition

of small-mammal catches. Some recognized factors of importance are time of year,

weather, and site disturbance.

Small-mammal populations generally are lowest in the spring because of overwinter mortality. Beginning in the spring, numbers increase owing to the addition

of young animals to the population. Populations are highest in fall. Dispersal of

animals, primarily young, into unoccupied habitat is greatest during late summer and fall. This is an important consideration when scheduling trapline transects, because such habitat may be quickly occupied by dispersing juveniles.

Deer mice are active during all kinds of weather, although abrupt weather

changes may alter their activity patterns. Sudden cold snaps, snows, or heavy

rains after mild weather will inhibit deer mouse (and chipmunk) activity. Nocturnal

mice show a reluctance to roam freely on bright nights, which results in generally

lower catches under full-moon conditions than on dark nights.

Most mice and shrews are nocturnal; chipmunks and ground squirrels are diurnal

and actively forage during the day. Leaving traps set for a minimum of 24 hours

therefore is necessary to get a representative sample of species in the area.

Live trapping-Capturing, marking, and releasing small mammals is a desirable

variation of the trapline transect (trapping) techniques described above. The major

advantages of live-trapping are:

. Animals are not removed from a population. This prevents other animals from

reoccupying an area after removal of trapped animals.

27
l Retrapping may be done at any time after initial trapping, thereby taking into

account variations in conditions caused by factors such as weather changes and

seasonal animal activities.

l Retrapping can be done at original trapping sites. This eliminates error caused

when a different population is sampled during retrapping.

Many techniques for kill-trapping and directions for analyzing results have been

described in previous section “Trapline transects.” This section covers modifications

that are necessary to apply live-trapping techniques to the trapline transect survey.

Equipment needed

l Twenty-five live-traps.

l Bait made of whole rolled oats or a mixture of whole rolled oats and peanut

butter.

l Raw wool for nest material.

l Cloth or plastic bags about 3-1/2 by 5 by 15 inches are recommended for

removing small mammals from Sherman-type traps.

Procedure+

l Shade traps from the sun, so that lethal air temperatures will not build up within

them.

l Shelter live-traps from direct rain impact, because they are not watertight.

Exposure to rain wets trap interiors and their contents, and often leads to

exposure and death of captured animals. Rain protection can be provided by

constructing bark shelters, or by placing traps under logs or similar cover. Strips

of tarpaper can be used effectively to keep traps dry.

. Place wool or cotton at the back of each trap to provide nesting material. This

may help ensure survival of trapped animals in inclement weather. Be sure that

the material does not interfere with the trigger.

l Animals may be removed from traps and handled safely by placing a cloth or

plastic bag over the rear of the trap, opening the trap door, and if necessary,

shaking the trap to dislodge the trapped animal. Wear gloves. The animal will

usually retreat into the bag, which then should be removed from the trap. Hold

the bag closed with one hand and grasp the animal by the nape of its neck with

the other hand. Invert the bag so the animal can be marked, examined, and

released. This method minimizes the chance of an animal escaping or of a

handler being bitten.

l All animals should be marked for identification, in the event of recapture. Marking

may be done in several ways. Toes of squirrels and chipmunks may be clipped,

or ears of mice may be notched. Both of these procedures may be used to

identify individual animals by marking a combination of toes or positions on the

ears. Numbered monel fingerling tags may be attached to the base of the ear.

Check with local wildlife officials to determine whether marking restrictions apply

in your area.

. Record marked animals by trapsite (see earlier section, “Stocking surveys”)

where originally marked and time of recapture.

28
. Summarize data by calculating the catch per 100 trapnights, enumerating only

those animals caught for the first time; disregard all recaptures.

Population trends, relative numbers, or amount of time animals used an area can

be estimated by counting pellet groups, mounds, runways, nests, evidence of feeding,

and similar signs. Indirect population measurements often are more easily obtained

than direct census, but require some type of calibration to relate the item counted to

the population density. For example, it is necessary to know the number of deer

pellet groups dropped per day when calculating deer-days of use by the pellet-group

method. Potential damage to natural seed fall, direct seeding, and spot seeding can

be predicted by measuring the rate at which small animals remove food from baited

spots.

Indirect Population

Estimates

Three types of surveys useful in gathering population information on forest mammals

and birds are pellet group counts, mound counts, and seed-spot surveys.

Counting Animal Signs Pellet-group counts-This section deals with procedures for collecting and

interpreting pellet group data for big-game population counts. Other pellet sampling

techniques have been developed for censuses of small mammals such as mice

(Emlen 1957) and hares (Adams 1959).

The following may apply to the use of pellet transects:

. Pellet-group counts can be used effectively where ground cover density does not

preclude accurate counting.

. Pellet-group counts provide a useful means of estimating the amount of big-game

use of different forest types.

. Population trends on specific areas can be estimated by comparing annual pelletgroup counts for 2 or more years.

. Fewer pellet-group plots are needed for determining population trends than for

estimating population density (Moore 1949).

. Pellet-group counts can provide useful information for preparing big-game harvest

recommendations. Data from a particular sampling area apply only to that area,

however, and should not be extrapolated to other areas.

Plot shape-Circular plots are recommended because they are more easily established by one person than are strip plots, and plot boundaries may be quickly and

simply located.

Plot size-A 1OO-square-foot plot with a radius of 5.6 feet is recommended.

Number of plots-The number of pellet plots needed will be influenced by the density and distribution of pellet groups and the sampling accuracy desired. Sampling

accuracy, suitable for most conditions, requires that the sampling error be within 20

percent of the mean 90 percent of the time. Preliminary sampling is necessary to

obtain data needed for computing sample size. After preliminary data are analyzed,

it will be possible to adjust plot numbers to obtain desired accuracy.

Sample stratification--More efficient sampling may be obtained by separating different vegetational units or cover types and sampling them separately. This will reduce variation in the sample and the number of sample plots needed.

29
A restricted random sampling procedure should be followed. The technique requires

the random selection of transect lines, which have a predetermined plot spacing.

Equipment needed--Variations in topography and cover on sample plots make

standard recommendations of equipment impractical. A small broom and dustpan may

be suitable for clearing pellet groups from plots that are open and free of large rocks.

A small rake, 8 inches wide, and a small shovel work better in heavy vegetation.

A light chain, 5.6 feet long, is suitable for locating plot boundaries. One end should

be looped for attachment to a pivot at the plot center. String or rope should not be

used because it may stretch.

Materials needed-The only materials needed for plot installations are pointed stakes

(1 by 2 inches by 2 feet) for plot hubs and a box of six-penny nails for pivots.

Procedures--Plots are “read” by slowly walking a circular path midway between the

center stake and plot boundary. The chain should be tight so that the plot boundary

is readily identified. The initial reading will include old as well as recent pellet groups.

All groups should be removed from plots or be marked, and estimates should be

made of the number of groups less than 1 year old. When plots are re-examined, all

new pellet groups will have been deposited since the last examination. If a pellet

group falls on a plot boundary, it is tallied if more than half of the pellets lie within the

plot. If more than one-half of the pellets are outside the boundary, the group is not

counted.

Frequency of counts-The type of information needed will determine the

frequencies at which plots are read. Monthly counts may be used to construct a

use-intensity curve for a given area. Semiannual readings, in spring and fall, are

normally sufficient on winter ranges. Summer range transects usually need to be

read once a year in a semiarid climate and twice a year in humid climates.

lnterpreting results-The number of deer-, elk-, or sheep-days of use per acre can

be estimated by dividing the total pellet group count for each species by 13, which

approximates the number of defecations per day by these animals. Although

defecation rates differ by seasons as animal diets change, they average about 13 per

day over a year for deer, elk, and sheep. The estimated rate of cattle defecation is

12 per day. Estimations of game or livestock numbers, per acre, should be related to

the amount of damage occurring.

Pocket gopher surveys-Two types of surveys are used to estimate pocket gopher

density. Gopher-mound surveys should be conducted when estimating population

density to determine whether controls are needed. Open-burrow surveys may be

used to evaluate effectiveness of baiting or trapping (see chapter 5, “Pocket

Gophers”).

Seed-Spot Surveys Seed-spot surveys can be used as a supplement to the trapline transect to obtain

information on the fate of seeds and to determine the damage agent(s). (Trapping

may be needed to identify the animals causing the seed loss.) They also provide

a way to measure rates of seed destruction or removal. The rate of seed loss, expressed as a percentage of the total seed spots, is easily determined. When seedspot surveys and trapline transects are used together, they should be spaced at least

5 chains apart to minimize any influence on small-mammal behavior.

Procedures The following procedures were developed by Moore (1949) for conditions in the

Douglas-fir region; the technique applies equally well to the pine region.

30
Locate 25 seed spots at l-chain intervals in roughly a straight line through the

sampling area. Transects should be located to sample representative habitat.

More than one transect may be required to sample large areas; a transect may

have to be broken in small areas. Whenever either condition arises, a minimum

of 5 chains should be allowed between lines. Spacing requirements should be

the same as those described for trapline transects.

Clear a spot about 1 foot in diameter of vegetation and debris to provide a

smooth surface that will aid in identifying animals (via tracks) visiting the spot.

Spread about 50 seeds in a line from 3 to 4 inches long on each spot. Cover half

of the seeds with a small piece of bark.

Mark the spot with plastic flagging.

Return in the morning after seed placement to record data and interpret results.

Avoid periods of snow or frost.

Materials needed-Conifer seeds and plastic flagging are needed to mark seed-spot

locations.

Records-Record results (see fig. 9). Instructions for completing the form are on the

back (fig. 10).

Summarizing results-Data are summarized as a percentage of the spots accepted

by birds or mammals. For example, if some seeds were eaten at 10 of the 25 spots,

this would represent 40 percent seed-spot acceptance.

Interpreting results-The following key is helpful in determining mammal or bird

species that have visited a seed spot:

l Seed spot not trampled, seed cover burrowed under: mice, shrews.

Seed mostly hulled or removed: mice.

Seed only partly eaten: shrews.

l Seed spot trampled: birds, chipmunks.

Only exposed seed eaten: birds.

Seed cover pushed aside: chipmunks.

Chipmunks and ground squirrels usually crack open a seed hull to remove the contents, leaving the two halves largely intact. Deer mice typically open one edge of the

seed, remove the endosperm, and leave an empty boat-shaped hull with clean-cut

edges at the opening. Shrews shred the seed hulls more completely and leave

serrated edges.

31
Seed Spot Survey

Observer: I D. Jones

Forest: I PNF District: Avery Date: 12/11/77

Location: Line no.: 1

Size of Area: 38 ac. Percent Slope: 45 Aspect: NW Elevation: 3,000

Weather: Overcast - calm - approx. temp - High 65, Low 45 F.

Ground cover: Recent Burn.

Area History: Clear cut and broadcast burned in Nov. 1968.

25 | X

Total 6 19

(total acceptance) 25 X UOO) = 24 (%spot acceptance)

Seed Spot Survey Results

Station Spot Acceptance

Number Yes | No Known or Suspected Animal

1 L Deer Mouse

6 H Deer Mouse

7 X

8 M Birds

9 X

13 X

14 X

15 A Deer Mouse

16 X

21 | X

22 | A Deer Mouse and Birds

23 | X

24 | H

Figure 9--Seed spot survey form (front).

32
Instructions

Observer: Forest, District.

Date: Self-explanatory.

Location: Give legal or local description.

Line number: To identify survey lines when more than one is used.

Size of area, slope, aspect, elevation: Self-explanatory.

Weather: List approximate high and low temperatures, wind conditions, precipitation,

and cloud cover conditions.

Ground cover: List dominant vegetation type and density, if vegetation is present on

the area. If a recent burn, list as such.

Area history: List management practices or abrupt natural changes that have taken

place on the area.

Station number: Be sure to read stations in the same sequence each time, to

facilitate comparisons among subsequent surveys.

Seed spot acceptance: If seeds have been removed from the spot, indicate the

degree of use with the following legend: L = light; M = medium; H = heavy; A = all.

Known or suspected animal: The following key will aid in identification:

- Seed spot not trampled, seed cover burrowed under: mice, shrews

Seed all hulled or carried off: mice

Seed only partly eaten: shrews

- Seed spot trampled: birds, chipmunks

Only exposed seed eaten: birds

Seed cover pushed aside: chipmunks

Map: Use the space below to show the seed spot pattern in relation to the

sample area.

. . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . .

. . . :TAGL FjR

*................ !...).. . . . . . . . . . . . . . . . . . . . : : : :

\sY IT NO. 2:

. . . ... ; -: ; .

. . .

6

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.

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. .......

: :

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.

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:

...

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....... ..............................

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....

.

.

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... ....

...

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. . . . .

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... .

........... ... ........ :.+$ l.... . . ....

-....i....;....:. “:....i....;....:

. . . . 8 . : : :

.

..‘.

:eî: : : : : .............. . . . : ........... .......... ........ . ...... . .....................

......... ... . , . .. :-: . .. . : : : : : :

... . .....

(I::

..... . ........... ..... . ...... .... . ................. . . . ..~~.~.~.~.~~.~..~.~~ . ... .... .

... . .... : . ....... . ..... . . . .... . . ... . . ........... . . . . ..9 .............. &.... . ............................

I

Figure 10-Seed spot survey form (back)

33
References Adams, L. 1959. An analysis of population of snowshoe hares in northwestern

Montana. Ecological Monographs. 29(2): 141-170.

Emlen, J.T. 1957. Dropping boards for study of small mammals. Journal of Wildlife

Management. 21(3): [pages unknown].

Gashwiler, J.S. 1959. Small mammal study in west-central Oregon. Journal of

Mammalogy. 40(1): 128-139.

Giles, R.H., Jr., ed. 1969. Wildlife management techniques. 3d ed., rev. Washington,

DC: The Wildlife Society. 623 p.

Julander, 0. [and others]. 1963. Measure of animal range use by signs. In: Range

research methods. Misc. Publ. 940. Washington, DC: U.S.Department of

Agriculture: 102-108.

Moore, A.W. 1949. Forest tree seed eaters and methods used to measure their

populations in the Pacific Northwest Douglas-fir region. University of Washington

Forest Club Quarterly. 23(1): 1-7.

Neff, D.J. 1968. The pellet-group count technique for big-game trend census and

distribution: a review. Journal of Wildlife Management. 32(3): 597-614.

Robinette, N.L.; Ferguson, R.B.; Gashwiler, J.S. 1958. Problems involved in the

use of pellet group counts. Transactions, 23d North American Wildlife Conference.

[Vol. and issue nos. unknown]: 411-425.

Sholl, M.C. 1968. Census methods for seed eaters. In: Proceedings, first reforestation

workshop: [dates of meeting unknown]; [Corvalis, OR ]. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Region: 86-90.

34
Chapter 4:

Methods for Managing Damage

Contents 36 Introduction

36 Chemical Toxicants

36 Safety in the Use of Toxicants

36 Characteristics and Uses of Lethal Agents

39 Repellents

39 Big-Game Repellent

40 Thiram

40 Hunting

40 Deer and Elk

40 Black Bear

41 Porcupine

41 Trapping

42 Trap Types and Sizes

44 Habitat Manipulation

44 Forage Fertilization and Use of Herbicides

45 Supplemental Feeding

45 Manipulating Habitat Carrying Capacity

46 Silvicultural Practices

49 Mechanical Protection of Seeds, Seedlings, and Trees

49 Area Protection

52 Seed Protection

54 Individual Tree Protection

57 References

35
Introduction Animal damage management methods have been developed for most animals of concern in forest and rangeland management. Many of these techniques are only partially

successful, however, and are used because more suitable methods are lacking.

No single method is considered completely effective under all circumstances, because the same species may respond differently to changes in habitat or other conditions. It is also common for more than one species to have caused a specific problem. These possibilities should be kept in mind when planning ADM. Depending on

the species involved, extent of damage, potential adverse impacts, and cost of management, any one of several techniques or a combination of techniques may be used,

including use of toxicants, repellents, hunting, trapping, habitat manipulation, and

mechanical protection.

Updated information on ADM methods may be available from your District, Forest, or

Regional wildlife biologist or silvicultural specialist, or from APHIS-ADC.

Chemical Toxicants Reduction of animal populations by use of chemical toxicants can sometimes be

achieved with a minimum of adverse effects.

Safety in the Use of

Toxicants

When using toxic materials, utmost care must be exercised in handling, storing, applying, and disposing of these compounds. Pesticides can be injurious to humans,

domestic animals, desirable plants, and fish or other wildlife if they are not handled

or applied properly. Use all pesticides selectively and carefully. Follow recommended

practices for the disposal of surplus pesticides and pesticide containers. Follow all

label directions, and follow all directions in FSM 2150.

Animals that eat other animals for food may absorb the toxicant loads of their prey

and be killed or affected in other ways (this is called secondary poisoning). Changes

in behavior in birds and mammals exposed to chemical toxicants, hatching-failure in

birds, and reduced reproduction in mammals may occur. The growth and survival

rates of the young produced also may be reduced. For mammals, these changes in

reproduction may affect both males and females. For birds, reproductive affects

usually occur in females. In cage tests with birds, behavioral effects have persisted

for three generations, after either the male or female of the first generation was

dosed with a pesticide (Caslick 1980). Land managers should recognize that the full

effects of toxicant use are difficult to study, even under laboratory conditions, and

very difficult to predict under field conditions. Toxicants selected for field use therefore

should be used in minimum effective amounts, and the possible secondary effects

should be considered.

For further information on using pesticides safely, and for information on the current

registration status of chemical toxicants in your area, contact pesticide-use specialists

in Districts, Forests, or Regional Offices, or APHIS-ADC.

Regional Foresters may delegate pesticide-use authority to other line officers, except

in designated wilderness, wilderness study areas, or designated or candidate research natural areas (FSM 2151.04a).

Characteristics and

Uses of Lethal Agents

Strychnine-Strychnine is derived from the seeds of a plant, Strychnine nux vomica,

grown in southern Asia. It is stable as a powder and relatively insoluble in water. Its

salts have a bitter taste and are not absorbed through normal skin contact.

36
Ingested strychnine is quickly absorbed, mainly in the intestinal tract. The principal

symptoms of strychnine poisoning, which may appear 5 to 30 minutes after ingestion,

are the result of increased reflex excitability of the spinal cord. The motor reflexes

are modified so that smaller stimuli are effective and the response to slight stimulation

is maximal and tetanic and tends to spread to all muscles; but tetanus (continuous

muscular contraction) depends on an enormous exaggeration of the “startle” reflexes

from a sudden stimulus or fright. This involves the simultaneous contraction of all

the muscles, which causes several secondary results such as asphyxia, increased

metabolism, disturbance of temperature, rise in blood pressure, increased heart rate,

and early postmortem rigor. Convulsive seizures may be interspersed by periods of

quiescence. Death usually occurs from the tetanic arrest of respiration in the course

of a major convulsion.

Strychnine baits may be consumed in sublethal quantities by target species. Animals

consuming sublethal doses of bait may develop an aversion to the bait and usually

avoid any remaining bait. Any mammal having access to bait may be killed, if sufficient bait is ingested.

Strychnine is not assimilated into tissues or bone. Predatory birds and mammals

have been killed by eating field-killed mice and rabbits that had strychnine-treated

grain in their guts.

Strychnine baits are restricted-use pesticides. Contact your local APHIS-ADC representative for instructions on ordering such baits from the Pocatello Supply Depot,

USDA APHIS-ADC, 238 E. Dillon, Pocatello, ID 83201.

Zinc phosphide-Zinc phosphide is a finely ground powder with a black or grayishblack metallic appearance. The pure compound is 76 percent zinc and 24 percent

phosphorus and has a disagreeable phosphorous odor. The chemical is stable when

dry and insoluble in water. When zinc phosphide comes in contact with dilute acids,

such as occurs in the stomach, phosphide gas (PH3) is released and absorbed into

the bloodstream. It takes several hours or occasionally several days for terminal

symptoms of convulsions, paralysis, coma, and death from asphyxia.

Zinc phosphide-treated baits have a garliclike odor and deteriorate very slowly; if kept

dry, lethal qualities are retained for at least 9 months. When exposed to rain, the bait

deteriorates rapidly; for example, up to 50 percent of the toxicant can be lost in 24

hours after exposure to heavy rains. Exposure to prolonged rain and moisture can

cause the loss of most of the toxicity in 2 or 3 days.

The risk of secondary poisoning of nontarget, predatory mammals and birds generally

is low, because poisoned rodents become sickened and usually seek refuge underground before dying. If raptors or predators were to ingest dead or dying rodents poisoned with zinc phosphide, they likely would become sickened and vomit the toxicant.

(Rodents are not able to vomit the bait.)

A risk to seed-eating birds and other rodents is present whenever baits are broadcast

or placed aboveground. Pheasants, quail, and waterfowl have been killed, occasionally in large numbers, when bait was broadcast on open ground where it could

be found readily.

Use extreme care in handling zinc phosphide-treated baits. Zinc phosphide can be

absorbed through the bare skin. (Never distribute baits with bare hands.)

37
Placement of bait in active runways of meadow voles greatly reduces the chance of

birds picking up the bait. Bait also can be placed in bait stations.

A 1.82-percent, zinc phosphide-treated grain bait is registered for use to control field

(meadow) voles (Environmental Protection Agency [EPA] registration 6704-6). Zinc

phosphide baits also are registered for control of pocket gophers, prairie dogs, ground

squirrels, woodrats, and commensal rats. Contact your local APHIS-ADC representative for instructions on ordering such baits from their Pocatello, Idaho, supply depot.

Order only the amount that will be used within 2 months.

Anticoagulants-Anticoagulants are chemicals that reduce or prevent the clotting of

blood and cause damage to the capillaries. Used as a poison, an anticoagulant

causes death by internal bleeding. Most anticoagulant baits seldom cause death in a

single feeding, although some new anticoagulants may require only a single feeding.

Feeding generally occurs over several days. Feeding does not have to occur on

consecutive days but should take place within a 10-day interval, with no longer than

48 hours between feedings. It is important that plenty of bait be available at all times.

Continued feeding on slow-acting anticoagulants, which can be accomplished by

broadcast baiting, is necessary to cause death. Bait stations (fig. 11) have been used

to facilitate multiple feeding on anticoagulant-treated baits in and around buildings, but

this is generally an impractical method for controlling small mammals in forest lands.

Second-generation anticoagulants, such as chlorophacinone and diphacinone, are

fast acting and require only a few feedings to cause death. With reasonable precautions in using anticoagulants, there is little danger to domestic animals or to

raptors and predators. Rodents poisoned with anticoagulants become sickened and

generally seek refuge underground before dying.

Figure 11-Bait box for use with anticoagulant baits in and around

buildings. Baffles reduce spillage and prevent rain, dirt, poultry

litter, and so forth, from contaminating the bait.

38
Several anticoagulants are registered for use in the United States and are marketed

under a variety of common and trade names, including Warfarin, prolin, coumafuyl,

brodifacoum, bromadiolone, chlorophacinone, diphacinone, pindone, and vapone.1

Most are not registered by the EPA for field use, but some are registered by California and Oregon for use in seed protection. The use of anticoagulants is recommended by APHIS-ADC and approved by the Forest Service for controlling rats and

mice in and around buildings.

Fumigants-Fumigants are used to produce a toxic atmosphere within the tunnels of

burrowing rodents or moles (and predators). Many factors, such as soil moisture,

composition, and porosity, influence the functioning of fumigants. The effectiveness

of fumigants is variable, and it usually requires much time and effort to fumigate each

individual burrow.

Aluminum phosphide tablets have been used successfully as a fumigant for control of

ground squirrels, Norway rats, and (under some conditions) moles. Fumigants have

the advantage over other toxicants of eliminating secondary hazards to nontarget

species.

Repellents Some chemicals have repellent qualities that cause avoidance by animals. Species

respond differently to various chemicals, with the result that no single chemical is a

universal repellent. Big-game repellent (BGR) and thiram (TMTD) are registered

repellents (Rochelle and others 1974). BGR is registered for use on conifer seedlings,

ornamental shrubs, and fruit trees. Thiram is registered for use on trees, shrubs, ornamentals, nursery stock, and coniferous seed in combination with other active

ingredients.

Big-Game Repellent Big-game repellent is a putrified protein product derived from whole eggs. This product is registered for foliage application to protect conifers from browsing by big

game. It is available in both liquid and powder formulations marketed as Deer-Away.

The product generally provides protection for about 60 days in most areas, but evaluate this on a trial basis for your local conditions. Best results are obtained in areas

with moderate to heavy browsing pressure (20 to 80 percent of terminals browsed).

The use of BGR in these areas may reduce use from 60 to 90 percent for 2 to 3

months. In areas with extreme use (more than 80 percent browsed), the repellent may

be less effective and browsing damage may not be reduced significantly.

Three to five acres per staff-day can be treated on rough terrain, and from 6 to 8

acres per day on slash-free areas on gentle terrain. The average treatment cost in

1981 (latest available data), for materials and labor to apply BGR to planted seedlings

in the field, ranged from $15 to $30 per acre.

On May 24, 1993, the Regional Forester, Pacific Northwest Region, suspended the

use of BGR in Region 6 pending the results of an EPA review of ethyl acrylate, a

compound used in the manufacture of the adhesive contained in the repellent formulation. On July 19, 1993, the EPA completed its review of Deer-Away (BGR product

produced by IntAgra, Inc.) and reported that it had no human health concerns about

the adhesive (specifically, that it had no concerns regarding the use of ethyl acrylate

in manufacture of one of the precursor chemicals in the adhesive) and has retained

registration for BGR.

‘The use of trade or firm names in this publication is for

reader information and does not imply endorsement by the

U.S. Department of Agriculture of any product or service.

39
Thiram

Hunting

Deer and Elk

Black Bear

Thiram (TMTD) has various common and trade names, including Arasan. Thiram is

an organic compound, tetramethylthiuram disulfide, which is formulated as a dust,

powder, liquid concentrate, or paste. It was developed originally as a fungicide. When

used as a foliage spray, it reduces damage by hares and rabbits for up to 60 days

but provides inconsistent protection from deer browsing. Thiram is phytotoxic and can

cause foliage damage at high concentrations. Some irritation of eyes, nose, and

throat have been reported by workers in contact with thiram-treated seedlings.

When a lo-percent suspension is properly applied in the nursery bed at the rate of

1 gallon per 5,000, 2-O conifer seedlings, thiram is nonphytotoxic.

Managed hunting is a useful tool that provides recreation and may also help reduce

animal damage. Sport hunting is usually the only acceptable method for reducing

big-game numbers to levels that will allow plantation establishment or prevent habitat

deterioration.

Animals that can be effectively controlled by hunting include deer, elk, bear, and porcupine. Heavy hunting with dogs may locally reduce rabbit populations. Sport hunting

also may be a cost-effective means of controlling coyotes.

In most states, big game may be controlled over large areas by using an either-sex

season, with a specific number of antlerless deer or elk permits issued. If a general

either-sex season fails to decrease the population, an early or extended season may

be warranted.

General season hunts, especially if restricted to taking males only, usually lack sufficient local intensity to be effective in reducing browsing problems. Controlled hunts in

and adjacent to problem areas therefore are more desirable.

Special hunts should not be recommended before the possible results of the hunt are

weighed against the high recreational and aesthetic values of the game animals

involved. Where the extent of animal damage is unacceptable, special control may be

justified. Study state wildlife regulations before attempting to develop recommendations to help solve damage problems caused by big game.

When problems caused by big game are detected, an immediate effort should be

made to determine the type and extent of damage and the numbers and species of

animals responsible. Careful documentation of problems may aid in securing assistance from state wildlife agencies.

Hunting pressure may be increased in specific areas by providing good road maintenance, adequate signs, maps, and publicity.

To reduce damage to conifers, black bears have been effectively managed in some

instances by the regulation of sport hunting. In Oregon and Idaho, for example, special hunts have been scheduled in spring, when bear damage is most prevalent. Sport

hunting with the use of hounds is particularly effective where allowed, but taking of

bears should be restricted to those areas where significant damage is occurring. In

most states, bear hunting is regulated by state wildlife agencies.

40
Porcupine

Trapping

Hunting porcupines to reduce damage is most effective after a fresh snowfall in the

winter. Trained dogs can greatly increase hunting success. Porcupine control should

be done in and adjacent to areas where damage is a problem. Porcupines are inactive during a snowstorm but move around soon after. During the period of activity

after a storm, porcupines can be tracked easily and killed. In spring and summer,

porcupines can be located by searching meadows and riparian areas in the evening

or early morning. Many porcupines can be located in this way, but because

porcupines are mobile, it is difficult to determine whether a summer hunting program

is effective in reducing subsequent damage.

Trapping may serve as a suitable method of controlling animal damage problems in

the following situations:

l Removal of ground squirrels remaining after poison baiting.

l Removal of problem beavers.

l Removal of problem bears.

l Control of ground squirrels, pocket gophers, porcupines, and mountain beavers

in localized areas.

. Protection of buildings and supplies from wild and commensal rodents (rats and

mice).

Consult your Forest wildlife biologist, biologists from the state wildlife agency, or

APHIS-ADC for information on trapping techniques specific to your area.

Most animals causing forest or range damage, with the exception of bears, are easily

trapped and may be taken with fully exposed traps. The main concern is to select

locations frequented by the target animal. Mice and rats prefer to travel under cover

of slash or vegetation or along walls in buildings. Ground squirrels and mountain

beavers usually stay close to their burrows. Rabbits prefer the protection provided by

slash and shrubby vegetation.

If a trap is not set in a natural runway or burrow, an attractant such as bait or scent

should be used. Suitable ground squirrel baits include wheat, oats, barley, and

apples. A mixture of peanut butter and whole rolled oats is a good bait for small mammals. Nut meats are good baits for woodrats. Fresh cuttings of succulent plants, such

as clover, dandelion, or alfalfa, may attract a variety of herbivores.

Current state regulations should be consulted to determine the exact status of an

animal in any given area. When game or furbearers are involved, it is necessary to

coordinate all proposed trapping with state wildlife agencies. The agency may either

take direct responsibility for handling the problem animals or issue special permits

allowing their removal.

The Animal Damage Control Program of APHIS-ADC has qualified biologists to consult whenever animal damage control is anticipated. They may either accomplish

needed animal control or provide on-the-job training to assist Forest Service

personnel in damage control.

41

HOW TO SET VICTOR GOPHER TRAP

DIAGRAM 1 DIAGRAM 2

Figure 15-Instructions for setting a Victor pocket gopher trap.

1. Hold the trap in both hands as show in diagram 1.

2. Place thumbs on upper frame (B) back of the jaws (A), with the other fingers underneath the lower

frame (C), diagram 1.

3. Lift the trigger (D) with the fingers and press down with the thumbs until the frame members are parallel.

4. Engage hood-end of trigger (D) in diagram 2 over end of upper frame (E); insert long end of trigger in

setting hole of pan (F).

5. Place the set trap in a pocket gopher burrow and cover the opening carefully with bark, grass, or other

natural materials. The jaws are in position to strike the body of the gopher.

Snaptraps--Simple design and low prices make snaptraps suitable for both surveying

and controlling small-mammal populations. Three sizes are available (fig. 16): the

small size (mouse trap) is suitable for mice and shrews; the large size (rat trap) is

suitable for ground squirrels, woodrats, and Norway rats. The Museum Special is

slightly larger than the mouse trap and is recommended for trapping chipmunks and

other small mammals of similar size. Traps are usually set on the ground or other flat

surface in spots protected from rain and exposure to birds.

Live-traps-Removal of problem animals alive and surveys by mark-recapture methods are best accomplished with live-traps. (Check with local state wildlife officials to

determine whether special state regulations apply.) Various sizes are available. The

smallest size, 3 by 3 by 10 inches, is suitable for mice, shrews, chipmunks, and

golden-mantled ground squirrels. The intermediate size, 5 by 5 by 15 inches, is

recommended for rats and squirrels. Larger sizes may be used for snowshoe hares

and mountain beavers. The Sherman trap (fig. 17) frequently is used to census small

mammals. The two smaller sizes of traps usually are made of sheet metal or aluminum. Larger sizes of live-traps (6 by 6 by 24 inches and 9 by 9 by 30 inches) usually

are welded wire. Both types are available in folding and nonfolding models.

43

Establishing game food patches called “Wildackers’ is a technique practiced in regulated hunting areas of Germany. These Wildackers are scattered through the forest,

forming chains of feeding areas that encourage animal movement. Food patches are

cleared of tree growth, fenced, cultivated, fertilized, and planted to game foods.

When supplemental forage is needed, fences are opened for access by deer. It is

expected that 3 percent of the forested area in parts of Europe eventually will be

devoted to the Wildackers.

Attempts have been made to reduce big-game damage to forest reproduction in the

Pacific Northwest by seeding and planting foods for big game. Douglas lotus, Dutch

white clover, alsike, yellow sweet clover, subclover, red clover, burnet, perennial rye,

orchard grass, fall oats, ceanothus, and other species have been sown for this purpose. These plantings generally have been heavily used by deer and elk. Observations indicate that damage to conifers by big game decreases in areas where supplemental browse has been provided (Baron and others 1966) but the practice has

not been widely adopted. If grasses are not sufficiently used in grazing, however,

high-quality habitat for voles may result in extensive damage to trees by the voles.

Grazing by domestic sheep and cattle in clearcuts during spring and summer is being

used as a method of preventing excess grass growth in the Pacific Northwest Region

of the Forest Service.

During periods of winter stress in the Rocky Mountains, deer and elk use conifer foliage and lichens knocked to the ground by snow and wind or made available by winter

logging and thinning operations. Resource managers should consider scheduling

thinning operations to attract browsing animals away from damage-susceptible conifer

plantations. Management to enhance sprouting of desirable hardwoods in areas

adjacent to vulnerable plantations can be used to develop attractive game food.

Sprouting can be encouraged by cutting hardwood species that have grown beyond

the reach of game. Application of herbicides and prescribed fire also may promote

basal sprouting (see earlier section, “Forage Fertilization and Use of Herbicides”).

Flowers (1987) tried supplemental feeding of black bears as a possible solution to

tree-barking problems in western Washington. (Tree damage by bears occurs shortly

after bears emerge from hibernation and when nutritious food is scarce.) He developed a food pellet containing sugar, protein, calcium, and other nutrients attractive to

bears. The results of this method for reducing tree damage, however, were

inconclusive.

Manipulating Habitat

Carrying Capacity

Reducing the attractiveness of habitat for wildlife has been used as a method of reducing animal damage. Broadcast slash burning delays population buildup by brush

rabbit and snowshoe hare after logging. Chemical weed and brush control offers

many possibilities for controlling animals by reducing available food or cover. A 1974

study showed that complete control of vegetation reduced the abundance of pocket

gophers and damage on plantations in southwestern Oregon (Black and Hooven

1974). In Washington, Borrecco (1976) found that the control of vegetation results in

a reduction of clipping by snowshoe hares on Douglas-fir seedlings.

Population control through habitat modification should be evaluated carefully, because

there is the potential of developing unexpected and possibly unwanted side effects.

This type of treatment also can have more impact on the ecosystem than would the

temporary population reduction resulting from direct control.

45
If undesirable browse plants are controlled by herbicide treatments, locally preferred

plant species may be released. This may temporarily improve the habitat for some

wildlife species, thereby increasing the risk of animal damage. Thinning dense conifer

thickets with established understory vegetation, by prolonging the productivity of an

area for wildlife, may have the same result.

Silvicultural Practices Modifications of present timber harvesting, slash disposal, and planting practices may

help reduce animal impacts on tree reproduction. Land managers must consider the

effects on wildlife and wildlife habitat that may occur after any silvicultural treatment.

When modifying silvicultural practices to control animal damage, the side effects of

the control measure must be weighed against possible benefits. For example, in certain areas, removing slash to reduce rabbit and rodent cover may increase use by

browsing animals.

Animal injuries to forest reproduction are seldom considered, unfortunately, until

actual damage to the stand has occurred. The potential impact of animal damage

to young trees often can be anticipated well in advance of harvest (see chapter 2).

Recognition of potential problem areas during the presale and replanting surveys will

allow action to minimize the impact of animal use on reforestation programs. Provision

should be made in sale prescriptions for damage control measures (FSM 2472.71).

Animal damage problems should be anticipated during presale surveys when any of

the following conditions occur:

. Big-game winter on the site. Areas having south and west slopes, protected

valleys and draws, and areas of low elevation often provide suitable wintering

grounds for big game. Deer and elk congregate in such areas during severe

weather and may use all available browse, including conifers.

. Big-game use is concentrated on areas other than winter ranges. Mixed timber

types, river bottoms, old burns, logged sites, game trails, and migration corridors

are favored spots.

l Big-game ranges are overpopulated. Excess numbers can occur when hunting

is prohibited or harvest is inadequate. Examples are municipal watersheds and

areas inaccessible to the public because of distance or because right-of-entry

through private property is denied.

l Heavy plant use or numerous tracks, trails, mounds, burrows, or droppings

indicate abundant animal activity.

l Use of mechanical tree planters promotes dispersal of pocket gophers and

creates conditions favorable for burrowing.

l Trees are planted on sites subjected to severe competition by herbaceous or

shrubby vegetation. Thus the trees will be unable to grow rapidly beyond the

reach of browsing animals.

l Trees are planted adjacent to older plantations that have a history of animal

damage.

When presale surveys indicate that an area has a high probability of animal damage,

plans should be made to manage it. Where special silvicultural prescriptions will not

provide the desired protection, provisions should be made to provide appropriate

physical or chemical protection.

46
An effort should be made to secure the cooperation and help of the state wildlife

agency in alleviating potential problems caused by big game. These efforts, based

on accurate and timely data on damage, may lead to special hunts, opening of areas

closed to hunting, or issuance of special kill permits.

Timber harvest-Cutting practices that protect existing stocking or control the quality

of animal habitat should be considered where animal problems are expected (FSH

2409.26b). Consideration also should be given to the feasibility of leaving corridors

for wildlife, moving the unit, or perhaps even deleting the unit.

. Leaving roosting and nesting trees for hawks and owls within or near areas to be

reforested may help maintain natural controls on rodent populations (FSM 2470,

5150), although these practices alone may not be sufficient to prevent

unacceptable animal damage.

Fuel treatment-The effects of broadcast burning on animal populations and

plantation survival must be evaluated carefully. Consider the advantages and

disadvantages of burning, as related to the needs and behavior of problem animals.

. Leaving slash from timber harvest and other fuels unburned tends to restrict

the movement of deer, elk, and livestock within a plantation. At the same time,

unburned fuels provide favorable habitat for maintenance of certain smallmammal populations (see chapter 1).

. Unburned fuels, when used as a barrier to browsing, provide protection to

individual conifers.

l Established browse plants remain as buffer food when slash and other fuel is

left unburned. This food source will increase rapidly, as shrubs respond to the

increased availability of light, moisture, and nutrients (see chapter 1).

. Broadcast burning facilitates access by deer, elk, and livestock to the entire

plantation. It also reduces the amount of material, such as light fuel, that can be

used to protect individual trees.

. Broadcast burning suppresses existing browse, which increases the vulnerability

of planted trees to deer and elk for the first year after burning.

. In some instances, broadcast burning causes direct mortality to lagomorphs and

rodents. The reduced protective cover also deters the rapid buildup of rabbit,

hare, and most rodent populations during plantation establishment, when

small-mammal feeding is most critical (see chapter 1).

. Broadcast burning provides quick release of soil nutrients, which may increase

the palatability of recently planted conifers (see chapter 1).

Piling and burning practices should disturb the site as lightly as possible and leave

20 to 30 tons per acre of debris, which can be used to protect tree seedlings. Light

disturbance of the site during piling will promote shrubs. Severe disturbance may

promote erosion on some soil types and may set a site back to the earliest successional stage, which generally encourages grasses and herbs attractive to rodents and

livestock (see chapter 1).

Reforestation practices-The methods followed to reforest denuded areas can

greatly influence the intensity of animal damage. If an animal-damage problem is

anticipated, reforestation practices can be selected to minimize damage.

47
Seeding in the late winter or early spring will minimize exposure of seed to seedeating mammals and birds.

Spring plantings can be made in areas where dormant-season damage is anticipated.

This will allow seedlings one growing season to become established, before exposure

to severe browsing or clipping damage. Spring-planted seedlings, however, are often

more easily pulled out by elk and deer than are seedlings with established root

systems.

Planting of less preferred species, where applicable, can help alleviate animal damage. In the Pacific Northwest, Douglas-fir and ponderosa pine are considered preferred browse for deer and elk at certain times of the year. White fir is highly preferred

in California. True firs and spruces are among the least preferred conifers. Sitka

spruce, for example, is seldom damaged by deer, elk, rabbits, or mountain beaver.

Tests of several provenances of ponderosa pine showed that some had natural

resistance to pocket gopher damage (Case 1983). In other areas, check with Forest

biologists to determine the tree species that local animals are least likely to use.

Animal damage usually is less harmful to large nursery-grown trees than to small

trees. Trees with larger stems and more foliage are better able to survive animalcaused injuries than are small seedlings. On suitable sites, the increased cost of

planting stock and planting usually is offset by greater seedling survival.

Planting trees under shrub canopies or slash may protect them from damage caused

by deer, elk, livestock, and porcupines. The shading also may be beneficial in some

areas.

Trees planted along well-used game trails or livestock trails often suffer heavy

browsing and trampling damage. To avoid such losses, trees should not be planted

within 8 feet of such trails.

On steep slopes, deer and elk generally feed uphill. Thus, trees planted on the uphill

side of stumps, logs, and rocks will receive some protection from browsing. Planting

close to large pieces of debris may provide protection from trampling.

In some instances, if significant animal damage is anticipated, this loss can be compensated for by increasing the numbers of trees planted. Reduced spacing is often

enough to compensate for moderate browsing of big game or the incidental damage

by pocket gophers and other rodents that occurs on many sites. It will not, however,

compensate for severe damage on sites exposed to repeated damage, where most

trees are being damaged or lost.

48
Mechanical Many techniques have been developed to physically protect seeds, seedlings, and

Protection of Seeds, trees. Direct protection prevents access, or excludes animals from individual trees or

Seedlings, and Trees entire plantations. Its application is limited, however, because it usually is the most

expensive type of protection available.

Physical protection of plantations usually is not needed on extensive areas but is

limited to sites where severe damage has occurred or has been predicted. For example, on plantations with several aspects, only the south slopes may need protection. Protection of only those areas normally free of snow may be sufficient in plantations ranging several hundred feet in elevation. Although the cost of physical protection is comparatively high, such treatment may ensure higher survival, thereby resulting in fewer trees being planted to obtain desired stocking (see the section below,

“Individual Tree Protection”).

Area Protection Deer fences-Areas of high damage potential can be fenced to exclude deer.

Fencing is one of the most common methods of game-damage control in Germany.

In areas where about 10 percent of forest land is fenced at all times, the fences are

maintained for about 10 years. As part of the program, deer and elk are provided

supplemental feed to compensate for their exclusion from more desirable wildlife

feeding areas.

Because fencing excludes deer from prime habitat, it should be used only when it is

apparent that reforestation cannot be accomplished by other means. Before fencing,

consider all ramifications of this practice.

Fence construction and maintenance costs are high, especially in rough terrain; however, costs per acre decrease rapidly as the size of the enclosed area increases.

Also, fewer materials are required per unit area to fence regularly shaped areas.

Excluding wildlife from large National Forest areas is not desirable from a multiple-use

standpoint, but it may be necessary temporarily for successful reforestation or necessary to protect seed orchards.

On large areas, it is difficult to avoid fencing in game animals. Enclosed deer and elk

are usually difficult and costly to remove, even by shooting or by providing escape

gates, Removal of trapped animals must be considered as a cost of protection, as

enclosing even a few animals may result in severe damage. To minimize possibilities

of fencing in game animals, fences should be constructed before vegetative cover

develops.

Deer are persistent in trying to gain access to preferred areas. Thus, fences must be

carefully designed, constructed and maintained to exclude deer. Regular maintenance

is necessary to prevent animals from penetrating fenced areas. If they gain access

but have difficulty leaving, damage may be heavier than if no fence existed.

Fencing one area may increase deer browsing in adjacent areas. Also, deer fencing

will not protect trees from rodent or hare damage, and it may increase brush

competition.

Electric fences-Electric fences, with the upper wire about 2 feet above the lower,

have been used to exclude deer from plantations but are ineffective for elk and

moose, which break through the fence on contact.

49
In addition, electric fences are ineffective in deep snow and may be grounded when

in contact with green vegetation. Power failures make them unreliable. Depending on

local conditions, high-tensile fences and slanted fences may provide protection. Check

with biologists from the state, the Cooperative Extension Service, or the APHIS-ADC

for local recommendations.

Woven wire fences-A properly constructed 8-foot-high woven wire fence usually will

exclude deer and elk (fig. 18). Woven wire fencing is available in 4-foot widths that

can be fastened together with hog rings to produce an 8-foot-high fence. Fencing

should not have openings larger than 6 inches. A 7-foot-high woven wire fence may

be used, if it is topped with two strands of wire. Fencing may be attached to posts of

wood or steel. If there is a possibility of timber blowdown, fences should be built

away from the timber edge to avoid excessive maintenance. A travelway adjacent to

the fence will facilitate maintenance.

Failure of woven wire fencing usually is a result of poor construction or lack of maintenance. Game animals frequently try to go under a high fence before attempting to

jump over it. Deer can work their way under a 4-inch space between the ground and

bottom wire, if the wire is slack. Spaces under fences should be filled with stones,

logs, or other debris. If the wire between posts cannot be pulled snugly to the ground,

it should be fastened to logs or stones that are large enough to hold the wire down. If

large logs or stones are not available, two stakes may be crossed over the bottom

wire and driven into the ground to close openings. Fences built along contours of

steep slopes must be higher than 8 feet or have outrigger attachments to prevent

animals from jumping over them.

Woven wire fences must be inspected periodically for damage by animal penetration,

snow, frost heaving, fallen trees, slides, and “washouts” under the bottom wire.

Restretch loose wire annually.

Cost of woven wire exclosures in the Pacific Northwest ranged from $2.40 to $4.85

per foot in 1984 (newer data not available). Maintenance for 5 to 7 years and

removal costs will about equal the original installation expenses.

Nylon net fence-Six-inch (diagonally stretched) mesh nylon netting has been used

in Oregon to exclude deer from plantations. An 8-foot-high fence is constructed

around a plantation by attaching the netting to steel fence posts (fig. 19). The netting

can be stretched and easily pegged down to conform to irregularities in the ground

surface. Netting should not be stretched tight, because this reduces its resistance to

impact.

When first used, nylon-net fencing was attached directly to trees surrounding cutting

units, but fence maintenance was high because of falling limbs and trees. Maintenance problems were reduced by moving fences away from standing trees and

attaching the netting to fence posts.

Nylon netting has not been in use long enough or in enough situations to permit

thorough evaluation of its effectiveness for protecting plantations. Nylon fencing will

exclude deer; it conforms to irregular surfaces, and construction and maintenance

costs are less than for woven-wire fences, but nylon fences are more susceptible to

vandalism. The anticipated life of the material is 5 to 7 years.

50

Seed Protection

“Beaver baffler” fence-The “beaver baffler” fence (fig. 20) was developed by the

Washington Department of Game. The use of the this fence to prevent beavers from

plugging culverts has been very successful (Fisher 1986, Guenther 1956).

The beaver baffler consists of a narrow lane of woven wire constructed around the

head of a culvert or through a dam and extended out into the stream or pond (fig. 21).

This lane should be at least 2-1/2 to 3 feet wide and extend 30 to 40 feet above the

culvert. Where a beaver dam is continually rebuilt, a fenced lane may be constructed

30 or 40 feet below the dam and extended through the dam out into the pond for 15

to 20 feet. This extension is built in 1 to 3 feet of water and may follow the shoreline,

if the lake or pond is deep. Posts must be placed closely enough to hold the wire to

the bottom of the pond. If the fence is properly installed, the beaver would have to

build a dam completely around the fence to hold water, but such behavior has never

been observed. Instead, they concentrate on pushing mud through the fence, crawling

over, or digging under the wire at the culvert or dam site.

Early experiments with fenced lanes 1-1/2 feet wide were not always successful, because beavers were able to push the wire together with mud and sticks. A persistent

beaver can dig under the fence, but its work is halted when the fenced lane has several cross sections of woven wire located near the beavers accustomed working

area. This prevents the beaver from carrying material inside the lane.

Fences are normally built 3 feet high. If it is necessary to build the lane in 3 feet or

more of water, higher wire must be used. The cost of new material to install a 30-foot

lane of fencing is usually less than the cost of making repeated trips to trap the beaver. Problem areas with heavy snow packs may require a top rail around the fence,

to support the wire when buried by deep snow.

Lane fences will save labor, expense, and time wherever they can be used to discourage an occasional unwanted beaver. Streams subject to flooding have not been

successfully fenced.

Alarm devices-Electronic noise makers, propane guns, whistles, horns, scarecrows,

flashing lights, and various other alarm devices have been used in attempts to protect

forest and agricultural crops from animals. Where short-term protection is necessary,

alarm devices are sometimes effective. Animals soon become accustomed to these

devices, however, and resume use of the area. Alarm devices have not proven effective for continuous protection of forest plantations or nurseries.

Conical seed protectors-Individual seed spots can be protected from ground squirrels, tree squirrels, chipmunks, and mice by covering them with wire screens. About

750 protective screens can be made from a roll of no. 3 mesh hardware cloth,

100 feet long and 3 feet wide. Using tin snips, the 3-foot rolls should be cut into five

strips 7-1/4 inches wide and 100 feet long. The protectors are cut from the narrow

strips with the aid of a parallelogram-shaped pattern made of plywood. Pattern dimensions are 7-1/4 inches high by 8 inches wide, the interior angles of 60 and 120

degrees. Large quantities of screen can be stamped out by machine. Screens can be

packed flat in boxes or bags for use in the field.

52

Individual Tree

Protection

In the field, the screen is rolled into a cone and held in this shape by folding the

cut-wire ends into the body of the screen. The protector is set by forcing the base

about 2 inches into the ground. When set, this protector has a basal diameter of

about 4-1/2 inches and a height of 5 inches. This type of screen provides at least 90

percent protection against small mammals during the first season. The screens

should be left in place through the growing season to keep rodents from destroying

the young seedlings, and then removed. Protectors can be reused several times.

Netting-Netting has been used successfully to protect a variety of agricultural crops

from depredating birds. The cost of netting and installation is generally quite expensive ($500 to $800 per acre in 1984) and can be justified only to protect high-value

crops such as berries, fruits, or tree seeds in nurseries. When used, care must be

taken to obtain netting with a small enough mesh to exclude undesirable birds. The

netting needs to be installed such that feeding through the net or gaining entrance

under the edges is eliminated.

Several companies produce various netting materials suitable for excluding birds

from high-value crops. Contact your local Cooperative Extension Service agent or

APHIS-ADC for current sources.

Plastic-mesh tubing-Enclosing individual trees with plastic-mesh tubing will protect

them from damage by mountain beavers, hares, rabbits, deer, and elk (Campbell and

Evans 1975a) and, to a lesser extent, pocket gophers. Where intensive protective

measures such as tubing or fencing are necessary for successful reforestation, tubing

has an advantage over fencing because it does not exclude wildlife from prime habitat. Tubes should be used only when extra planting of 30 or 40 percent will not yield

sufficient stocking, and they should be used only where they are cost effective. Extensive use of plastic tubing to protect plantations is expensive, and costs increase

rapidly as terrain becomes steeper and rougher. In addition, cost per unit area for a

specific number of tubes is fixed; it does not decrease with additional area as does

the cost of fencing. (Larson and others [1979] is an excellent reference for tube

installation.) It is very important not only to install the tube correctly, but also to use a

tube diameter large enough to allow the tree to develop and grow as normally as possible. Four- to five-inch-diameter tubes should be used for pines. For Douglas-fir and

western larch, 3-1/4-inch-diameter tubes are recommended. Diamond twill pattern is

recommended as it is the most rigid. Other patterns are more flexible and tend to

bend over more. A 3/8-inch mesh opening is recommended.

There will be some growth distortion of tubed trees, due to tube bending or new

growth being caught in the mesh opening. The large diameter (recommended above)

will help alleviate distortion. Annual maintenance of the tubes should be included in

tubing operations. Tubes can be ordered with different breakdown rates. For Rocky

Mountain sites, tubes should be ordered that have 30- to 40-month photobreakdown

rates. For other areas, local experience and local management guidelines should be

followed.

The number of trees to be tubed should be governed by the stocking required in a

specific area. The presence and condition of “natural” seedlings as well as those

trees seeded or planted always should be considered when assessing stocking

adequacy. For additional details see Campbell and Evans (1975; also in appendix 3

of this handbook).

54
Obstructions-Constructing barriers over and around young trees may effectively

protect them from big game and domestic livestock and partially protect them from

other wildlife (fig. 22). Materials such as tree limbs and other debris normally are

available after logging, site preparation in brush fields, or fires. It may be necessary

to cut small, fire-killed trees or shrubs for additional material. Protection costs using

this technique differ relative to the availability of materials and the number of trees

protected per acre.

Tree guards-Tree squirrels can be discouraged from climbing individual trees, such

as in a tree-seed orchard, by placing a 2-foot-wide metal band around the trunk of

the tree, about 6 feet above the ground. Because tree squirrels are excellent jumpers,

the bands are ineffective if branches of unprotected trees are near enough to permit

jumping between trees.

Beavers can be discouraged from cutting individual trees by encircling the lower

3 feet of the tree with l-inch mesh wire fencing. Allow room for tree growth, and

replace as needed.

Bud caps-Bud caps are effective against browsing by big game, particularly in

winter and early spring. Caps should be used on stock strong enough to support a

cap without bending over. Generally, stems 114 inch in diameter at the point of

installation will support a cap. Bud caps are effective for one growing season and

may need to be replaced annually for 3 years before seedlings are free to grow.

Areas without protection being browsed at 50- to 70-percent rates should expect to

have damage reduced to about 10 percent of terminals browsed.

Many types of bud caps have been tried; the style shown in figure 23 has proven

very effective. This cap uses a piece of 8-1/2- by 5-1/2-inch waterproof paper and

five staples. One staple is used to hold the top of the cap together. The other staples

are used in pairs on each side of the stem just below the bud, to hold the cap firmly

in place. The terminal bud should be positioned in about the center of the tube, with

4 inches of the tube above the bud and 4 inches of stem in the tube below the bud.

No more than 25 percent of the foliage should be stapled inside a cap. Some

Districts in Region 6 have reported heat damage to the leader from using this type of

cap. Bud caps made of polypropylene netting are now available; they may reduce or

eliminate this heat damage. Bud caps should be tried first on a small scale to

determine their usefulness under local conditions. Although bud capping is not widely

used for animal damage reduction, it may be useful in some situations.

55

References Baron, F.J.; Nord, E.C.; Evanko, A.B.; Makel, W.J. 1966. Seeding conifers and

buffer crops to reduce deer depredation. Res. Note PSW-100. Berkeley, CA: U.S.

Department of Agriculture, Forest Service, Pacific Southwest Research Station.

8 P.

Bartik, M.; Piskac, A., eds. 1961. Veterinary toxicology. Amsterdam, Oxford, New

York: Elsevier Scientific Publishing Co. 346 p.

Black, H.C., ed. 1969. Proceedings, symposium on wildlife and reforestation in the

Pacific Northwest; 1968 September 12-13; Corvallis, OR. Corvallis, OR: Oregon

State University, School of Forestry. 92 p.

Black, H.C.; Hooven, E.F. 1974. Response of small-mammal communities to habitat

changes in western Oregon. In: Black, H.C., ed. Proceedings, symposium on

wildlife and forest management in the Pacific Northwest; 1973 September 11-12;

Corvallis, OR. Corvallis, OR: Oregon State University: 177-186.

Borrecco, J.E. 1976. Controlling damage by forest rodents and lagomorphs through

habitat manipulation. In: Siebe, C.C., ed. Proceedings, 7th vertebrate pest

conference; 1976 March 9-l 1; Monterey, CA. Davis, CA: University of California:

203-210.

Boyd, R.J. 1967. Vegetation management and animal damage. In: Baumgartner,

D.M.; Mahoney, R.L.; Evans, J. [and others], eds. Proceedings, workshop on

animal damage management in Pacific Northwest forests; 1987 March 25-27;

Spokane, WA. Pullman, WA: Washington State University, Cooperative Extension:

55-58

Brown, E.R.; Mandery, J.H. 1962. Planting and fertilizing as a possible means of

controlling distribution of big game animals. Journal of Forestry. 60 (1): [pages

unknown].

Campbell, D.L.; Evans, J. 1975a. “Vexar” seedling protectors to reduce wildlife

damage to Douglas-fir. Wildl. Leafl. 508. Washington, DC: U.S. Department of the

Interior, Fish and Wildlife Service. 11 p.

Campbell, D-L.; Evans, J.A. 1975b. Improving wildlife habitat in young Douglas-fir

plantations. In: Sabol, K. H., ed. Transactions, 40th North American wildlife and

natural resources conference; 1975 March 16-19; Pittsburg, PA. Washington, DC:

Wildlife Management Institute: 202-208.

Case, R.M. 1983. Pocket gophers. In: Timm, R.M., ed. Prevention and control of

wildlife damage. Lincoln, NE: University of Nebraska: B-13 to B-17.

Caslick, J.W. 1980. Effects of insecticides on birds and mammals Misc. Bull. 109.

Ithaca, NY: Cornell University. 14 p.

Caslick, J.W.; Decker, D.J. 1979. Economic feasibility of a deer-proof fence for

apple orchards. Wildlife Society Bulletin. 7(3): 173-175.

Fisher, P.H. 1986. Keeping beavers from plugging culvert inlets. In: Engineering

Field Notes. Washington, DC: U.S. Department of Agriculture, Forest Service; 18:

9-13.

57
Flowers, R.H. 1987. Supplemental feeding of black bear in tree damage areas of

western Washington. In: Baumgartner, D.M.; Mahoney, R.L.; Evans, J. [and

others], eds. Proceedings, workshop on animal damage management in Pacific

Northwest forests; 1987 March 25-27; Spokane, WA. Pullman, WA: Washington

State University: 149-153.

Giles, R.H., ed. 1969. Wildlife management techniques. 3d. ed. Washington, DC:

The Wildlife Society. 623 p.

Grisez, T.J. 1960. Slash helps protect seedlings from deer browsing. Journal of

Forestry. 58: 385-387.

Guenther, S.E. 1956. Beaver baffler. Olympia, WA: Washington State Game Bulletin.

8(3): 3-6.

Keyes, J.; Smith, C.F. 1943. Pine seed-spot protection with screens in California.

Journal of Forestry. 41: 259-264.

Larson, J.E.; Campbell, D.L.; Evans, J.; Lindsey, G.D. 1979. Plastic tubes for protecting seedlings from browsing wildlife. ED&T 2217. Missoula, MT: U.S. Department of Agriculture, Forest Service, Equipment Development Center. 19 p.

Longhurst W.M.; Jones, M.B.; Parks, R.R. [and others]. 1962. Fences for

controlling deer damage. Circ. 514. Davis, CA: University of California, Division of

Agricultural Sciences. 19 p.

McCabe, R.A. 1970. Vertebrate pests: problems and control. Principles of plant and

animal pest control. Washington, DC: National Academy of Sciences, National

Research Council, Subcommittee on Vertebrate Pests. 153 p. Vol. 5.

McCracken, H.; Van Cleave, H. 1947. Trapping: the craft and science of catching

fur-bearing animals. New York: A.S. Barnes. 196 p.

Radwan, M.A. 1963. Protecting forest trees and their seeds from wild mammals: a

review of the literature. Res. Pap. PNW6. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment

Station. 28 p.

Radwan, M.A. 1970. Destruction of conifer seed and methods of protection. In:

Dana, R.H., ed. Proceedings, 4th vertebrate pest conference; 1970 March 3-5;

West Sacramento, CA. Davis, CA: University of California: 77-82.

Rochelle, J-A.; Gauditz, I.; Oita, K.; Oh, J.H.K. 1974. New developments in

big-game repellents. In: Black, H.C., ed. Proceedings, symposium on wildlife and

forest management in the Pacific Northwest; 1973 September 11-12; Corvallis,

OR. Corvallis, OR: Oregon State University, School of Forestry: 103-112.

Thompson, W.T. 1981. Agricultural chemicals. Book III: Fumigants, growth regulators, repellents, and rodenticides. Fresno, CA: Thompson Publications. 182 p.

Timm, R.M., ed. 1963. Prevention and control of wildlife damage. Lincoln, NE:

University of Nebraska, Cooperative Extension Service; Great Plains Agricultural

Council.

Webb, W.L. 1966. Forest wildlife management in Germany. Journal of Wildlife

Management. 24(2): [pages unknown].

58
Chapter 5

Wildlife Problem Species and

Their Management

Contents 61 Large Mammals

61 Rocky Mountain Elk, Wapiti

63 Roosevelt Elk, Wapiti

66 Mule Deer

68 Black-Tailed Deer

72 White-Tailed Deer

76 Black Bear

80 Small Mammals

80 Shrews

82 Moles

84 Rodents in Campgrounds

84 Uinta Ground Squirrel

86 Belding (Oregon) Ground Squirrel and Columbian Ground Squirrel

87 Golden-Mantled Ground Squirrel

89 Black-Tailed Prairie Dog

91 Chipmunks

93 Tree Squirrels

59
96 Pocket Gophers

115 Beaver

119 Nutria

120 Meadow Voles

123 Deer Mouse

125 Pine Mouse

126 House Mouse

126 Woodrats

129 Porcupine

133 Mountain Beaver

139 Woodchuck

141 Snowshoe Hare

144 Black-Tailed Jackrabbit

146 Nuttall’s (Mountain) Cottontail

147 Brush Rabbit

148 Birds

150 Blue Grouse

152 Bird Pests (Starlings and Sparrows)

60
Large Mammals

Rocky Mountain Elk,

Wapiti

(Cervus elaphus nelsonl)

Description-A large member of the

deer family with a pale yellow rump

patch, small tail, and reddish brown

body. Elk can weigh up to 1,000

pounds. Males have huge spreading

antlers. Cows are much smaller, rarely

weighing more than 600 pounds.

Economic significance-The Rocky

Mountain elk is one of the most prized

game animals. Money spent in its

pursuit provides a substantial source of

income to local communities that furnish

services and supplies.

Overgrazing by elk in localized areas

may cause range and watershed

problems when populations are allowed

to exceed carrying capacity. Rocky Mountain elk also may cause serious problems in

forest regeneration, and in some areas, elk depredations cause serious economic

losses to ranchers. When forced by hunger, elk will use orchards and haystacks to

supplement their diets.

Life history informationPreferred habitat--Rocky Mountain elk are found in timbered mountainous areas.

Favored habitats include meadows and grasslands for feeding and dense timber for

cover. Optimum habitat has gentle terrain and free-running water available during

summer. Areas disturbed by fire or logging usually support a diversity of vegetation

and are attractive to elk. A good distribution of escape cover is needed to make these

areas more desirable.

Feeding habit-shrubs, forbs, grasses, and sedges form the basic diet, but

significant quantities of forbs and browse are used seasonally. During spring and

early summer, succulent grasses, sedges, and forbs make up the major portion of

the diet of Rocky Mountain elk. As grasses and sedges mature during late summer

and early fall, the diet shifts to shrub species, which stay succulent longer. Wintering

can occur on open bunchgrass or shrub ranges, as the highly adaptable elk will use

whatever food source is most readily available. The two daily feeding periods are in

the morning-from just before to several hours after daylight-and in the early

evening. Winter feeding periods are more frequent and erratic.

Acfivity--Elk normally cover several miles a day as they feed during spring,

summer, and fall. In winter, they are more sedentary and feed heavily in one area

before moving to another. Migration from summer to winter range usually takes place

in late November and December. Some routes are more than 100 miles, but they

usually are much shorter.

Elk are gregarious and travel in herds most of the year. Herd size is greatest from

late summer through winter. Older bulls are more solitary, are often found alone, and

tend to winter at higher elevations.

Elk make well-defined trails. They usually bed on gentle slopes, benches, or

ridgetops.

61
Reproduction--Rocky Mountain elk are polygamous. Their main breeding period is

from late August through September. The gestation period is 249 to 262 days, with

the calf drop occurring from late May to mid-June. Breeding age of cows normally

begins at 2-1/2 years, although 1-1/2 year-old cows may breed. Bulls 1-1/2 years old

are capable of breeding and are significant breeders in many heavily hunted populations. Many Rocky Mountain elk herds have high calf production rates, with a 35 to

50-percent annual rate of population increase possible.

Damage problems and their managementBrowsing-Elk, possessing lower incisors only, leave a splintered break on browsed,

dormant woody stems (see fig. 1). Spring browsing may cause the bark to slip from

the browsed twig, resulting in a stripped stem below the break. Small, newly planted

seedlings may be pulled out by elk, especially on wet or loose, sandy soils. Where

large numbers of planted seedlings are missing completely and elk are numerous, elk

may be responsible. Elk also bark shrubs and small deciduous trees, particularly

willow and cottonwoods. Elk may seriously damage plantations by trampling, particularly along trails and in loafing and bedding areas.

Grazing--Grazing use is difficult to differentiate from that of livestock. The best way

to identify the impact of elk use on rangelands is by a combination of surveys. A

range survey (FSH 2209.21) can be used to evaluate total forage use, and a series

of pellet-group-count transects (see chapter 3), which can be read once or twice a

year, can be used to separate big-game use from domestic stock use.

Deferming the need for damage management-Browsing on conifers is frequently

highest immediately after planting in new clearcuttings. When forage plants become

well established in a harvest unit, the amount of conifer use declines. A survey, such

as the reforestation stocking survey, should be made to gather information to evaluate

degree of use by elk. Browsing of 20 percent or less of the terminal shoots is usually

not sufficient to warrant control, because a plantation may sustain the effects of such

browsing without serious growth loss. Elk prefer to feed near bedding areas, and

damage may be concentrated near them. Some plantations can be adequately protected by treating only those areas on gentle to moderate slopes. Overuse by grazing

is frequently the result of excessive use by both big game and domestic livestock.

The type of control depends on the land-management objectives for the particular

area and the ability to implement control practices.

As in most damage situations, the best predictive information can be found by evaluating adjacent areas having similar conditions and history.

Management methodsHunting--increased elk damage to plantations or forage areas may be related to

habitat deterioration. Downward trends in the condition of big-game habitat must be

brought to the attention of the state wildlife agency and the public that does the

hunting.

Silviculfural modifications-leave sufficient debris on the site after site preparation

to provide seedling protection and forage for elk. When planting on wintering areas,

plant as late in the spring as is consistent with other reforestation practices, use large

2-O planting stock, plant seedlings in spots protected by debris or other obstructions,

and plant seedlings a minimum of 8 feet from well-used elk trails. On steep hillsides,

plant in or above debris piles.

62
Habitat manipulation-Consider forage fertilization, supplemental food development,

or improvement of forage species composition to lessen impacts on planted trees

(see chapter 4).

Area protection-Properly constructed, 8-foot high, woven-wire fences will exclude

elk, but this procedure is costly and seldom used other than for very high-value plantations. Resource managers must weigh the advantages and disadvantages involved

in fencing portions of National Forest System lands.

Individual tree protection--Tubing or bud caps on individual trees will protect them

from elk damage (see chapter 4). For additional details see Campbell and Evans

(1975; also reprinted in appendix 3).

Repellents-Big game repellent can be used to provide short-term protection to

seedlings (see chapter 4 and section on black-tailed deer).

References--References for Rocky Mountain elk are combined with those for

Roosevelt elk and are found at the end of that section (below).

Roosevelt Elk, Wapiti

(Cervus elaphus

rooselvelti)

Description-The Roosevelt elk is the

largest subspecies of North American

elk. Mature bulls weigh 700-1,000

pounds and mature cows 400-700

pounds. The antlers of the Roosevelt

elk are generally shorter, less

symmetrical, more massive, and have

a narrower spread than those of the

Rocky Mountain elk. The wintercoat

is heavy with dark brown coloring on

head, neck, and legs. The sides are

a much lighter grayish-brown, and a

large rump patch is whitish-yellow

in color. The summer coat is more

reddish brown.

Economic significance--Roosevelt

elk of the Pacific slopes of Washington,

Oregon, and northern California are

highly valued by both outdoor enthusiasts and those who wish only to observe and

photograph the animals. (About 8,000 Roosevelt elk are harvested annually in

Washington and Oregon.)

In some areas, feeding damage constitutes an important loss in forest plantations.

Plantation damage also may occur when elk trample young trees.

Life history informationPreferred habitat-Roosevelt elk generally range west of the Cascade Crest in

Oregon and Washington. They favor forest ranges that provide a mosaic of young

and mature stands interspersed with grassy openings and narrow streamside meadows. During summer, elk in the Olympic Mountains and on the western slopes of

the Cascade Range in Oregon and Washington may migrate to high mountain

meadows.

63
Optimum habitat includes about 60 percent cover, gentle southerly or flat exposures,

and a free-running water source, all in close proximity.

Feeding habits-shrubs, forbs, grasses, and sedges are all eaten readily at some

period of the year. Elk use of Douglas-fir differs with season and availability of other

food materials. Succulent new growth on Douglas-fir is frequently eaten, even when

there is an abundance of other food. Western hemlock occasionally constitutes a

major food in winter. Elk generally feed upslope in steep country. Roosevelt elk

seldom feed more than 200 yards from suitable hiding or escape cover.

Activity--Roosevelt elk are most active just before dawn and again in late afternoon.

Daytime activity increases during winter, when food is less abundant. Home ranges

average about 2 to 4 square miles for nonmigratory populations. Migratory populations follow the receding snow to summer ranges at higher elevations. Most elk return

each year to the same wintering area. Roosevelt elk normally feed over a large circular route, moving slowly through each feeding area and then moving on. A typical

small band of elk makes a complete circuit of its feeding area in about 2 or 3 weeks.

Reproduction--RooseveIt elk are polygamous. Most breeding takes place between

September 15 and October 15. Most yearling bulls are capable of breeding. Preseason populations have 2 to 10 percent antlered bulls. On good range, females

usually breed during the second fall after birth. The gestation period is from 8 to

8-1/2 months, and calves are dropped from mid-May through June. Less than 1

percent of births are twins. Cows in the wild are believed to be capable of bearing

young for at least 20 years. Lactating cows are frequently in such poor condition that

fewer than half become pregnant. Most cows with calves are still lactating during the

breeding season. Studies have shown that 75 to 85 percent of dry cows and all cows

in areas with high-quality forage are capable of conceiving.

The mean annual population increase depends on many factors, with quality of

forage, herd density, and age structure being most important. Herds are capable of

increasing at a rate of 25 to 40 percent per year.

Damage problems and their managementIdentification-Elk, possessing lower incisors only, leave a splintered break on

browsed, dormant woody stems. Spring browsing may cause the bark to slip from the

browsed twig, resulting in a stripped stem below the break. Small, newly planted

seedlings occasionally are pulled up by elk, especially in loose, sandy, or pumice

soils. Elk also bark shrubs and small deciduous trees, particularly willows and

cottonwoods. Areas damaged by elk often are related to movement patterns. Elk

usually travel in small bands, making well-defined trails. They bed most often on

gentle slopes, benches, or ridgetops.

Determining the need for damage management-Although use of clearcuttings by

Roosevelt elk is heaviest 6 to 8 years after logging, severe damage to coniferous

seedlings may occur immediately after planting. Moderate to heavy browsing damage

may occur throughout stand establishment and continue until terminal shoots of

Douglas-fir and other conifer saplings are out of reach of the elk. Rubbing the antlers

on trees may cause serious injuries, but it seldom kills the trees.

64
A survey should be made to gather information to evaluate degree of use by elk.

Browsing of 20 percent or less on the terminal shoots usually is not significant enough

to warrant control, because the plantation may sustain the effects of such browsing

without serious growth loss. Some plantations can be adequately protected by treating

only those areas preferred by elk that are on gentle to moderate slopes.

As in most damage situations, the best predictive information can be found by

evaluating adjacent areas with similar conditions and history.

Management methodsHunting--lncreased elk damage to plantations may be related to habitat deterioration. Downward trends in the condition of big-game habitat should be brought to the

attention of the state wildlife agency, so that hunting pressure may be increased.

Silvicultural modifications-Plant on elk wintering areas as late in spring as is consistent with other reforestation practices; use large planting stock (24 to 30 inches

high), plant seedlings in spots protected by slash or other obstructions, and plant

seedlings a minimum of 8 feet from well-used elk trails. On steep hillsides, plant in or

above debris piles.

Habitat manipulation-Consider forage, fertilization, supplemental food development,

or improvement of forage species composition to lessen impact of elk damage to

planted trees.

Area protection--Properly constructed, 8-foot high, woven-wire fences will exclude

elk. Resource managers must weigh the advantages and disadvantages involved in

fencing portions of National Forest System lands, however.

lndividual plant profection--Use plastic tubing or bud caps on the minimum number

of trees desired for the site. Treat only those areas likely to be exposed to heavy elk

browsing. For additional details see Campbell and Evans (1975) in appendix 3 of this

handbook.

Repellents-Big-game repellent can be used to provide short-term protection (see

chapter 4 and section on black-tailed deer in this chapter).

ReferenceBecker, J.M. 1989. Forage enhancement in the Pacific Northwest: improving elk

habitat and forest regeneration. Seattle, WA: University of Washington, College of

Forest Resources. 55 p. M.S. thesis.

Black, H.C.; Dimock, E.J., II; Evans, J.; Rochelle, J.A. 1979. Animal damage to

coniferous plantations in Oregon and Washington. Part 1: a survey, 1963-1973.

Res. Bull. 25. Corvallis, OR: Oregon State University, School of Forestry, Forest

Research Laboratory. 45 p.

Borrecco, J.F.; Black, H.C. 1990. Animal damage problems and control activities on

National Forest System lands. In: Davis, L.R.; Marsh, R.E.; Beadle, D.E., eds.

Proceedings, 14th vertebrate pest conference; 1990 March 6-8; Sacramento, CA.

Davis, CA: University of California: 192-198.

Campbell, D.L.; Evans, J.A. 1978. Improving wildlife habitat in young Douglas-fir

plantations. In: Sabol, K., ed. Transactions, 40th North American wildlife and

natural resources conference; 1975 March 16-19; Pittsburg, PA. Washington, DC:

Wildlife Management Institute: 202-208.

65
decalesta, D.S. 1983. Elk. In: Timm, R.M., ed. Prevention and control of wildlife

damage. Lincoln, NE: University of Nebraska, Cooperative Extension Service:

D-35 to D-43.

Harper, J.A.; Harn, J.H.; Bentley, W.W.; Yocum, CF. 1967. The status and ecology

of the Roosevelt elk in California. Wildlife Monograph 16. Washington, DC: The

Wildlife Society. 49 p.

Harper, J.S. 1971. Ecology of Roosevelt elk. [Location of publisher unknown]:

[Publisher unknown]; Federal Aid Project W-59-R Oregon State Game

Commission. 44 p.

Rochelle, J.A. 1979. Effects of forest fertilization on wildlife. In: Gessel, S.P.;

Kenady, R.M.; Atkinson, W.A., eds. Proceedings, forest fertilization conference;

1979 September 25-27; Seattle, WA. Inst. For. Resour. Contrib. 40. Seattle, WA:

University of Washington, College of Forest Resources: 163-168.

Rochelle, J.A. 1992. Deer and elk. In: Black. H.C., tech. ed. Silvicultural approaches

to animal damage management in Pacific Northwest forests. Gen. Tech. Rep.

PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station: 333-349. Chapter 16.

Swanson, D.O. 1970. Roosevelt elk-forest relationships in the Douglas-fir region of

the southern Oregon Coast Range. Ann Arbor, Ml: University of Michigan. 173 p.

Ph.D. dissertation.

Thomas, J.W.; Toweill, D.E., eds. 1982. Elk of North America: ecology and

management. Harrisburg, PA: Stackpole Books. 698 p.

Witmer, G.W.; Wisdom, M.; Harshman, E.P. [and others]. 1985. Deer and elk. In:

Brown, E.R., ed. Management of wildlife and fish habitats in forests of western

Oregon and Washington. Part 1: Chapter narratives. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Region: 231-258.

Chapter 11.

Mule Deer

(Odocoileus hemionus)

Description-Mule deer differ considerably in

size; bucks may weigh more than 300 pounds

live weight. Pelage is dark gray during fall and

winter months, reddish brown in summer. Large

ears, white rump, and a short, round tail with a

black tip and hairless undersurface are typical

mule deer characteristics. Antlers branch in a

dichotomous manner.

Economic significance-The mule deer is an

important big-game animal, in both total kill and

hunter days of effort. For example, during the

1982 hunting season, more than 60,000 mule

deer were harvested in northern Idaho and

Montana, 21,000 of which were taken from

National Forest System lands. Serious

reforestation problems can occur in plantations within or

adjacent to deer winter range. Most damage occurs from mid-fall through spring.

66
Life history informationPreferred habitat-Mule deer use nearly all habitat types that provide suitable food,

cover, and water. Preferred topography includes open forests and broken brushlands

on steep and rugged terrain.

Foods and feeding-Mule deer are primarily browsers and consume woody forage

throughout the year. In fall and early spring, however, grasses make up a significant

part of their diet. Forbs are used extensively during late spring and summer.

Acfivity--Daily movements are from 1 to 2 miles on summer range. On winter range,

daily movement is much more restricted, generally about 1/4 mile, if undisturbed.

Most feeding is done in late evening and early morning; however, in winter it takes

place throughout the day. Mule deer tend to be gregarious. This is particularly true

during winter, when they often form groups of 10 or more.

Reproduction-Mule deer are polygamous. Breeding takes place from late October

through early December. The gestation period is 196 to 210 days, with the fawn drop

occurring in June. Most deer breed at 16 to 18 months of age. During the first two

pregnancies, single fawns are normal; thereafter, twin births are common. The average number of fawns per doe is 1.5. Potential productivity is 50 to 60 percent annual

increase, but net productivity seldom exceeds 20 to 40 percent in most herds.

Damage problems and their managementBarking-Antler polishing by mule deer leaves tree bark in a shredded condition, with

long frayed strips of bark hanging at the top and bottom of the barked area. Antler

polishing is generally restricted to an area between 1 -1/2 and 3-1/2 feet above the

ground. Preferred targets are small, live, open-growth saplings 3/4 to 1-1/2 inches in

diameter, generally restricted to an area between 1-1/2 and 3-1/2 feet above the

ground.

Browsing-Deer feeding on woody vegetation leave a ragged splintered edge during

the dormant season, although early spring browsing may result in the bark slipping,

thereby leaving a stripped stem some distance below the break. Browsing of new

growth usually leaves a clean, blunt stem-end, where the tender shoots were broken

off. Browsing seldom occurs more than 4 feet above the ground, except in deep

snow situations (see chapter 2).

Grazing--Deer use of grass and forbs is best differentiated from use by domestic

livestock and other ungulates by the use of pellet transects (see chapter 3).

Need for management-Antler polishing occurs sporadically and control is generally

impractical. Browsing of less than 20 percent of the terminals is generally not a

serious problem on established plantations.

The amount of deer use on rangelands that is required to constitute damage will

depend in part on the objectives set for the area. If a combined deer-livestock

overuse situation occurs, and if reduction in deer or livestock use is anticipated,

pellet transects can help document the amount of deer use.

67
Management methodsHunting-Controlling mule deer damage by hunting is often feasible because the

animals occupy open habitat and form groups in late fall. Hunting should not be considered a panacea, however, because in preferred habitats with large deer populations, tree damage may occur even though large herd reductions are made. Roads

into the problem areas should be kept open and maintained during the hunting

season to promote increased deer harvest.

Silvicultural modifications-Leave 20 to 30 tons per acre of debris on the site after

site preparation. When planting on or near deer winter range, plant as late in the

spring as is consistent with other reforestation practices. Do not plant trees within 8

feet of well-used deer trails. Practice obstruction planting (see chapter 4).

Habitat manipulation--Consider forage fertilization, supplemental food development,

or improvement of forage species composition to lessen impacts on planted trees

(see chapter 4).

Area protection-An 8-foot fence will effectively protect most plantations. If plantations are in deer migration routes or are subject to extremely heavy deer pressure, a

woven wire fence should be used. Area protection has a number of disadvantages

and should not be used if other protective measures will be equally effective (see

chapter 4). Managers must determine the feasibility of this based on local conditions

and current costs.

Individual tree protection--Tubing or bud caps on individual trees will protect them

from deer damage (see chapter 4). For additional details see Campbell and Evans

(1975; also reprinted in appendix 3).

Repel/en&-Big-game repelllent may be applied to seedlings to provide protection

(see chapter 4 and black-tailed deer). Thiram can be used as a brush-on during the

dormant season.

References-References for mule deer are combined with those for black-tailed deer

and are found at the end of that section (below).

Black-Tailed Deer Description-The black-tailed deer is smaller

(Odocoileus hemionus than the mule deer, its closest relative. Adult

columbienus) black-tailed does average 110 to 130 pounds live

weight, with an occasional doe weighing up to

145 pounds. Adult bucks average 120 to 160

pounds, although an occasional buck may

exceed 200 pounds live weight. The summer

pelage is typically reddish brown, in contrast to

the winter coat, which is predominately brown

to gray-brown. The tail is broad at the base

and narrows gradually to a rounded tip. The

outer surface of the tail is dark brown to black,

with a white undersurface. The rump patch is not

as pronounced as in the typical mule deer. When

startled, black-tailed deer often raise their tail as

a flag, similar to the behavior of white-tailed deer.

68
Antlers of black-tailed deer branch in a dichotomous manner, typical of mule deer.

Antlers begin growth in April and are dropped from mid-December to March. Antlers

of most yearling black-tailed deer and many 2 year olds develop as spikes. Branched

antlers are rare for yearlings but are most common for 2 and 3 year olds.

Economic significance-The black-tailed deer is the most important game animal

west of the Cascade crest, with about 90,000 harvested annually in Washington and

Oregon.

Black-tailed deer usually are able to meet their year-long habitat needs within a

limited area, and as a result they exert a steady pressure on forest crops. Conifer

plantations often are set back as much as 5 years because of heavy deer feeding.

Life history informationPreferred habitat-Black-tailed deer range west of the crest of the Cascade Range

in Oregon and Washington. They occupy a wide range of habitats and thrive in areas

of subclimax vegetation that develop after fire or logging.

Feeding habits--Black-tailed deer are primarily browsing animals, but they also consume a wide variety of herbaceous plants. As grasses and forbs become available,

the volume of browse in the diet decreases. Use of conifers differs as a result of

abundance, location, time of year, availability of other foods, and deer population

density. The feeding pattern on steep slopes is generally uphill. Black-tailed deer

seldom venture more than 200 yards from escape cover while feeding.

Activity-Daily movements are usually only a few hundred yards in extent. Many

black-tailed deer are nonmigratory and spend most of their lives within an area of 1

to 2 square miles. In the more mountainous portions of their range, black-tailed deer

may seasonally move to higher elevations. Migrations seldom exceed 1 mile. Deer

moving into the Cascade Range migrate several miles to spend summer at upper

elevations and return in fall to winter ranges that are usually below 2,000 feet.

Reproduction-Black-tailed deer are polygamous. Breeding takes place from late

October to early December, with the peak occurring in mid-November. They usually

breed as yearlings, but the greatest productivity is in the 3-1/2- to 6-1/2-year age

group. The gestation period is about 208 days. The average fawn-per-doe ratio in

good habitat is about 1.2 and in poor habitat is about 0.8. Black-tailed deer have

reproductive rates of 35 to 65 percent per year, with habitat conditions being the

principal control on population growth rate.

Damage problems and their managementBarking-Antler polishing by black-tailed deer leaves the bark in a shredded

condition with long frayed strips of bark hanging at the top and bottom of the barked

area. Antler polishing is generally restricted to an area between 1-1/2 and 3-1/2 feet

above the ground. Preferred targets are small live saplings 3/4 to 1-1/2 inches in

diameter.

Browsing-Deer feeding on woody vegetation leave a ragged, splintered stem during

the dormant season, although early spring browsing may cause the bark to slip, which

leaves a stripped stem some distance below the break. Browsing of new growth

usually leaves a clean, blunt end where the tender shoots were broken off. Browsing

seldom occurs more than 4 feet above the ground, except in deep snow situations.

69
Winter and summer browsing damage to Douglas-fir and other conifers is a widespread problem in the Pacific Northwest (Borrecco and Black 1990). Summer

browsing is common in many areas; it starts soon after spring bud burst and

continues into the summer.

Determining the need for damage management-Antler polishing occurs sporadically and in such a manner that control is generally impractical. Browsing of less

than 30 percent of the terminals is generally not a serious problem on established

plantations.

Management methodsHunting-Sport hunting to regulate black-tailed deer numbers is the most desirable,

although not always the most effective, method of controlling browsing damage to

plantations. Deer population levels that can be maintained in this way without causing

damage to other forest resources must be determined from a knowledge of local habitat conditions and deer use patterns. Obtaining a harvest that will produce a desired

population level is primarily the result of coordination with the state wildlife agency

and the hunting public. Roads into the problem areas should be kept open and maintained during the hunting season to promote increased deer harvest.

Silvicultural modifications-Leave logged areas unburned to restrict deer access to

trees and to preserve existing food. When planting on deer winter range, plant as late

in the spring as is consistent with other reforestation requirements. Mix tree species

and include those that local experience has indicated are of low preference. Plant

stock 24 to 30 inches tall with leader diameters of 3/8 inch or larger. Plant seedlings

in spots protected by slash or other obstructions and a minimum of 8 feet from wellused deer trails. Plant on the uphill side of logs, stumps, rocks, and other obstructions

when on steep hillsides.

Habitat manipulation-Consider possibilities for reducing browsing pressure on conifers by improving quantity and quality of food in areas away from damage-susceptible

plantations.

Area protection-Gameproof fencing is an effective method of controlling deer use

in plantations, if it is economically feasible. It restricts other uses on the area, however, and should be used only after other protection alternatives have been evaluated

and judged inappropriate.

/ndividua/ tree Protection--Plastic-mesh tubing or bud caps on individual trees are

effective in protecting trees from deer damage. Tubing should not be used on steep

slopes where deep snow cover normally occurs. For additional details see Campbell

and Evans (1975; also reprinted in appendix 3).

Repellents--Big-game repellent, a putrified protein product derived from whole eggs,

is available in both liquid and powder formulations. It is registered for the protection

of conifer seedlings (Douglas-fir, noble fir, grand fir, and ponderosa pine) from blacktailed deer and Roosevelt elk in the Pacific Northwest (see chapter 4). These repellents may be applied to seedlings in the nursery bed or by backpack sprayer to newly

planted or established seedlings in the field. The recommended use during the

growing season is to apply deer repellents to new growth immediately after bud burst.

70
ReferencesBlack, H.C.; Dimock, E.J., II; Evans, J.; Rochelle, J.A. 1979. Animal damage to

coniferous plantations in Oregon and Washington. Part 1: a survey, 1963-1973.

Res. Bull. 25. Corvallis, OR: Oregon State University, School of Forestry, Forest

Research Laboratory. 45 p.

Borrecco, J.E.; Black, H.C. 1990. Animal damage problems and control activities on

National Forest System lands. In: Davis, L.R.; Marsh, R.E.; Beadle, D.E., eds.

Proceedings of the 14th vertebrate pest conference; 1990 March 6-8; Sacramento,

CA. Davis, CA: University of California: 192-198.

Brown, E.R. 1961. The black-tailed deer of western Washington. Biol. Bull. 13.

Olympia, WA: Washington State Game Department. 124 p.

Campbell, D.L.; Evans, J. 1978. Establishing native forbs to reduce black-tailed

deer browsing damage to Douglas-fir. In: Howard, W.E., ed. Proceedings, 8th

vertebrate pest conference; 1978 March 7-9; Sacramento, CA. Davis, CA:

University of California: 145-151.

Craven, S.R. 1983. Deer. In: Timm, R.M., ed. Prevention and control of wildlife

damage. Lincoln, NE: University of Nebraska: D-23 to D-33.

Crouch, G.L. 1966. Preferences of black-tailed deer for native forage and Douglas-fir

seedlings. Journal of Wildlife Management. 30(3): 471-475.

Crouch, G.L. 1980. Post-season hunting to reduce deer damage to Douglas-fir in

western Oregon. Res. Note PNW-349. Portland, OR: U.S. Department of

Agriculture, Pacific Northwest Forest and Range Experiment Station. 6 p.

Gourley, M.; Vomocil, M.; Newton, M. 1987. Mitigating deer browse damageprotection or competition control? In: Baumgartner, D.M.; Mahoney, R.L.; Evans, J.

[and others], eds. Animal damage management in Pacific Northwest forests; 1987

March 25-27; Spokane, WA. Pullman, WA: Washington State University,

Cooperative Extension Service: 113.

Hines, W.W. 1973. Black-tailed deer populations and Douglas-fir reforestation in the

Tillamook Burn, Oregon. Game Rep. 3. Corvallis, OR: Oregon Department of Fish

and Wildlife, Research Division. 59 p.

Longhurst, W.M.; Leopold, AS.; Dasmann, D.F. 1952. A survey of California deer

herds, their ranges and management problems. Bull. 6. Sacramento, CA:

California Department of Fish and Game. 136 p.

Mackie, R.J.; Hamlin, K.L.; Pat, D.F. 1982. Mule deer (Odocoileus hemionus). In:

Chapman, J.A.; Feldhamer, G.A., eds. Wild mammals of North America: biology,

management, and economics. Baltimore, MD: Johns Hopkins University Press:

862-877.

Radwan, M.A. 1972. Differences between Douglas-fir genotypes in relation to

browsing preference by black-tailed deer. Canadian Journal of Forest Research.

2(3): 250-255.

Rochelle, J.A. 1992. Deer and elk. In: Black. H.C., tech. ed. Silvicultural approaches

to animal damage management in Pacific Northwest forests. Gen. Tech. Rep.

PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station: 333-349. Chapter 16.

71
State of Oregon. 1980. The Oregon interagency guide for conservation and forage

plantings. Portland, OR: State of Oregon, Oregon State University and Oregon

Department of Fish and Game; U.S. Department of Agriculture, Forest Service

and Soil Conservation Service; U.S. Department of the Interior, Bonneville Power

Administration and Bureau of Land Management. 84 p.

Taber, R.D.; Dasmann, R.F. 1958. The black-failed deer of the chaparral, ifs life

history and management in the north Coast Range of California. Game Bull. 8.

Sacramento, CA: California Department of Fish and Game. 163 p.

Taylor, R.H.; Johnson, R.L. 1976. Big game habitat improvement project in western

Washington. Olympia, WA: Washington State Department of Game; job

completion report; project W74-R-4. 220 p.

Wolertz, W.C. 1987. Evaluating deer damage control in ponderosa pine plantations

on the Paisley Ranger District. Lakeview, OR: U.S. Department of Agriculture,

Forest Service, Fremont National Forest. 83 p.

White-Tailed Deer

(Odocoileus viginianus)

Description-The white-tailed deer is smaller than the mule deer and black-tailed

deer, although the species differs widely in size throughout ifs range. Pelage is graybrown during fall and winter, reddish brown in summer. Large fail, white beneath;

antlers (males only) branch from main beam.

Economic significance-The white-tailed deer is the most common and widely distributed deer in North America and is the most important big-game animal in the

Nation, in both kill and hunter days.

There is direct competition between white-tailed deer and domestic livestock, particularly on deer winter ranges. Much of this range is privately owned and is used by

ranchers as spring and fall range. When forage competition becomes keen, the

ranchers may be faced with downward adjustments in stocking or supplemental

feeding. In either case, they may suffer a financial loss.

Serious reforestation problems can occur in plantations within or next to deer winter

range. Most damage occurs from mid-fall through spring. In hardwood forests,

browsing on understory vegetation may cause extensive damage to young tree seedlings. The estimated cost of this damage to hardwood forest landowners in Pennsyllvania was estimated at $13 per acre per year if control measures (including fencing,

fertilizing and herbiciding) were not used (Tilghman 1984). In Eastern forests, deer

have seriously damaged oak and aspen regeneration. They also have inflicted

browsing damage on planted white pines.

For some areas, guidelines are available for integrating deer management and timber

management (Pruitt and Pruitt 1986). Consult with your National Forest wildlife biologist for updates on this topic.

Life history informationPreferred habitat-White-tailed deer use various habitat types. Topography does not

appear to be a constraint to use; however, preference for mesic sites, such as flood

plains, marshes, and stream bottoms, does exist.

72
Feeding habit-White-tailed deer are primarily browsers and consume woody forage throughout the year. In spring, grasses make up a significant part of the diet.

Forbs make up a substantial part of the diet during spring and summer months. The

winter diet consists primarily of browse species, with conifers being a locally significant component, where available.

Activity--In northern climates, daily movements are from 1 to 2 miles on summer

range. On winter ranges, daily movement is much more restricted, generally about

1/4 mile if undisturbed. Most feeding activity is in late evening and early morning;

however, if may fake place throughout the day in winter.

White-tailed deer tend to be gregarious during the rut and particularly during the

winter.

Reproduction-White-tailed deer are polygamous. Breeding fakes place from midNovember through early January. The gestation period is 185 to 200 days. Most

female white-tailed deer breed at 18 months of age.

Damage problems and their managementBarking-Antler polishing by white-tailed deer leaves the bark in a shredded condition, with long-frayed shreds of bark hanging at the fop and bottom of the barked

area. Antler polishing is generally restricted to an area between 1-1/2 and 3-1/2 feet

above the ground. Preferred targets are small, open-grown saplings 3/4 to 1-1/2

inches in diameter.

Browsing-Deer feeding on woody vegetation leaves a ragged splintered edge

during the dormant season, although early spring browsing may result in the bark

slipping, which leaves a stripped stem some distance below the break. Browsing of

new growth usually leaves a clean, blunt stem end where the tender shoots were

broken off. Browsing seldom occurs more than 4 feet above the ground, except in

deep snow situations (see chapter 2).

Grazing--Deer use of grass and forbs is best differentiated from use by domestic

livestock and other ungulates by the use of pellet transects (see chapter 3).

Need for management-Antler polishing occurs sporadically and control is generally

impractical. Browsing of less than 20 percent of the terminals is generally not a

serious problem on established plantations.

The amount of deer use on rangelands that is required to constitute damage will depend in part on the objectives set for the area. If a combined deer-livestock overuse

situation occurs, and if reduction in deer or livestock use is anticipated, pellet transects can help document the amount of deer use.

Management methodsHunting--Managing deer damage by sport hunting is often feasible where animals

occupy open habitat and form into groups in late fall. Hunting should not be considered a panacea, however, because in preferred habitats with large deer populations,

free damage may occur even though large herd reductions are made. Keep roads

open to encourage hunting.

73
Silvicultural modifications-Similar to mule deer (see previous section on mule

deer). In addition, fertilization to promote rapid seedling growth or use of fencing to

temporarily exclude deer from recently harvested areas has proven very successful in

achieving successful reforestation on the Allegeheny National Forest in Pennsylvania

(Tilghman 1984).

Habitat manipulation--Consider forage fertilization, supplemental food development,

or improvement of forage species composition, to lessen impacts on planted trees

(see chapter 4). Opening the overstory to discourage deer browsing during the regeneration period has been helpful in trials at the Ottawa National Forest in Michigan.

Area protection-An 8-foot fence will effectively protect most plantations. If plantations are located in deer migration routes or are subject to extremely heavy deer

pressure, a woven wire fence should be used. Area protection has a number of

disadvantages and should not be used if other protective measures will be equally

effective (see chapter 4).

Where nurseries experience high levels of deer damage, a permanently installed

woven wire fence will likely prove to be effective. Several designs have been used

successfully by orchard owners; an 8-foot-high mesh fence topped with two strands

of wire (about 1 and 2 feet above the woven wire) has generally been cost-effective

(Caslick and Decker 1979).

A 1985 survey of 55 users of high-tensile electric fencing for controlling deer damage

to orchards and field crops in the Northeast indicated that fence performance was

excellent, although a majority reported that deer penetration did occur (Ellingwood

and others 1985). A study of 12 randomly selected fences showed that most were in

poor operating condition and needed better maintenance.

Several fence designs to exclude deer from hardwood regeneration cuts have been

fried over the last 30 years at the Allegheny National Forest in Pennsylvania. An

8-foot woven wire fence has proven effective (1980 cost: $0.81/lineal ft). In their trial

of plastic mesh fencing, initial construction costs were less, but increased maintenance costs more than made up for initial savings, when compared with the woven

wire fence (Tilghman 1984).

A recent evaluation of an electronic device that emitted auditory and visual stimuli

showed no effectiveness in protecting hardwood seedlings in Alabama from deer

(Roper and Hill 1985). In this test, the AV-ALARM electronic scare device produced

the sound and strobe light.

Individual tree protection-Tubing or bud caps on individual frees will protect them

from deer damage (see chapter 4). For additional details see Campbell and Evans

(1975; also reprinted in appendix 3).

Repellents--Big-game repellent may be applied to provide protection (see chapter 4).

Thiram can be used as a brush-on during the dormant season.

74
Many compounds have been investigated for their potential use as systemic deer

repellents. Because they would be absorbed by the plant, they would have the advantages of not being washed off and protecting new growth. Only the naturally occurring element selenium has shown potential for this use. In studies with penned

white-tailed deer at Pennsylvania State University, selenium provided some protection

for white ash and black cherry seedlings, but further research is needed with freeranging deer to evaluate repellency of systemic selenium (Angradi and Tzilkowski

1987). Field tests in Washington, in 1984, failed to confirm adequate repellency of

selenium-treated seedlings to black-tailed deer (Black and Lawrence 1992).

ReferenceAngradi, T.R.; Tzilkowski, W.M. 1987. Preliminary testing of selenium-based

systemic deer browse repellent. In: Holler, N.E., ed. Proceedings, 3d Eastern

wildlife damage conference; 1987 October 18-21; Gulf Shores, AL. Auburn, AL:

Auburn University, Cooperative Extension: 102-107.

Black, H.C.; Lawrence, W.H. 1992. Animal damage management in Pacific

Northwest forests: 1901-90. In: Black, H.C., tech. ed. Silvicultural approaches

to animal damage management in Pacific Northwest forests. Gen. Tech. Rep.

PNW-GTR-287. Portland, OR: U.S Department of Agriculture, Forest Service,

Pacific Northwest Research Station: 23-55.

Caslick, J.W.; Decker, D.J. 1979. Economic feasibility of a deer-proof fence for apple

orchards. Wildlife Society Bulletin. 7(3): 173-175.

Craven, S.R. 1983. Deer. In: Timm, R.M., ed. Prevention and control of wildlife

damage. Lincoln, NE: University of Nebraska, Cooperative Extension: D-23 to

D-33.

Ellingwood, M.R.; McAninch, J.B.; Farigone, M.J. 1985. Current status of deer

fencing in the Northeast. In: Bromley, P.T., ed. Proceedings, 2d Eastern wildlife

damage conference; 1985 September 22-25; Raleigh, NC. Raleigh, NC: North

Carolina State University, Cooperative Extension: 180-185.

Jagman, H. 1984. White-tailed deer habitat in north Idaho. Moscow, ID: University of

Idaho. 36 p. M.S. thesis.

Martinka, C.J. 1968. Habitat relationships of white-tailed and mule deer in northern

Montana. Journal of Wildlife Management. 32(3): 558-565.

Mundinger, J.G. 1980. Population ecology and habitat relationships of white-tailed

deer in coniferous forest habitat of northwestern Montana. [Location of publisher

unknown]: Montana Department of Fish and Game, Federal Aid Project; W-122-R;

progress report, July 1, 1979-June 30, 1980: 8-92.

Owens, T.S. 1981. Movement patterns and determinants of habitat use of white-tailed

deer in northern Idaho. Moscow, ID: University of Idaho. M.S. thesis.

Palmer, W.I.; Wingard, R.J. 1982. Electric deer fencing. College Park, PA:

Pennsylvania State University, School of Forest Resources. 11 p.

Pengelly, W.C. 1961. Factors influencing production of white-tailed deer on the

Coeur d’Alene National Forest, Idaho. [Location of publisher unknown]: U.S.

Department of Agriculture, Forest Service. 190 p.

75
Black Bear

(Ursus americanus)

Pruitt, L.R.; Pruitt, S.E. 1986. Effects of northern hardwood management on deer

and other large mammal populations. In: Proceedings of a symposium: managing

northern hardwoods: [dates of meeting unknown]; [location of meeting unknown].

Syracuse, NY: Syracuse University, College of Environmental Science and

Forestry: 363-380.

Roper, R.B.; Hill, E.P. 1985. An evaluation of visual and auditory electronic devices

to repel deer. In: Bromley, P.T., ed. Proceedings, 2d Eastern wildlife damage conference; 1985 September 22-25; Raleigh, NC. Raleigh, NC; North Carolina State

University: 186-191.

Shaw, H.G. 1962. Seasonal habitat use by white-tailed deer in the Halter Creek

enclosure. Moscow, ID: University of Idaho. 36 p. M.S. thesis.

Tilghman, N.G. 1984. Deer densities and forest regeneration. In: Decker, D.J., ed.

Proceedings, 1st Eastern wildlife damage control conference; 1983 September

27-30; Ithaca, NY. Ithaca, NY: Cornell University, Cooperative Extension Service:

[pages unknown].

Tilghman, N.G. 1986. Deer populations and their impact on regenerating northern

hardwoods. In: Proceedings, managing northern hardwoods; [dates of meeting

unknown]; Syracuse, NY. Syracuse, NY: Syracuse University, College of Environmental Science and Forestry: 286-297.

United States Steel Company. 1980. How to build fences with USS Max-10, 200

high-tensile fence wire. Pittsburgh, PA: U.S. Steel. 75 p.

Description-Black bears may weigh 200

to 500 pounds and reach a height of 2 to 3

feet at the shoulders. Their color ranges

from cinnamon or black to a light brown,

and usually a small patch of white is on

the breast.

Economic significance-Black bears are

game animals in most states. Most black

bears are shot incidentally by people

hunting deer and elk. There also is

considerable sport hunting with hounds in

local areas where bears are abundant.

Bear pelts are of only minor importance in the U.S. fur market. The largest outlet is in

England where the furs are used in making hats. Poaching of bears to obtain body

parts, such as gall bladders, for an illicit foreign trade has become a serious problem

in all regions, particularly in the Southeast United States.

Bear damage in forests is localized; however, this damage is expected to increase as

more plantations reach pole size. Bear damage was found to be three times higher in

thinned versus unthinned blocks in Montana (Schmidt 1987). There, the 6- to 8-inch

diameter at breast height (d.b.h.) class had 63 percent of the bear damage. Thinned

blocks with moderate damage may still yield significantly more board feet per acre

than unthinned stands with less damage. Supplemental feeding of bears may result

in hazards to humans and is not recommended.

Life history information76
Preferred habitat-Dense forests with scattered mountain meadows and areas of

berry-producing shrubs provide ideal habitat. Bears seldom venture far from escape

cover.

Feeding habits--Succulent herbs, roofs, grasses, nuts, fruits, insects, and animal

flesh are readily eaten, with vegetable matter making up the bulk of their diet. In many

areas, bears do considerable damage to young conifers during May, June, and July

by stripping off bark to feed on the sap and inner tissue. They prefer fast-growing,

smooth-barked frees 5 to 15 inches d.b.h. They bite the bark off or peel if downward

and then scrape the sapwood with upward movements of their lower incisors.

Activity--The size of the home ranges of bears differs considerably by habitat type.

In western Washington, for example, the home range of female black bears is about

1 square mile and about 30 square miles for males (Poelker and Hartwell 1973). In

Montana, the home range of female and male black bears is 207 acres and 1,233

acres, respectively (Jonkel and Cowan 1971). Information has been tabulated on

translocation distances of live-trapped black bears to determine how far they must be

moved to minimize their chances of returning (Rogers 1986).

Reproduction-Black bears are polygamous. Most breeding takes place during June

and July, and females usually breed every other year. Breeding begins when the

animals are 3-1/2 years old. The gestation period is from 7 to 7-1/2 months. Cubs are

born in January or February while the mother is still in the den. Twins are normal;

singles and triplets are not uncommon. The average annual population increase is

about 5 to 12 percent.

Damage problems and their managementIdentification-Black bears leave large strips of bark around the bases of trees they

peel. Long vertical grooves in the sapwood are left by the incisors as the bear strips

off the outer layers of sapwood (fig. 24), in contrast to rodents that leave short

horizontal or diagonal grooves in barked stems.

Determining the need for damage management-Before a bear removal program

or other bear management practice is begun, stand exam information needs to be

reviewed closely to determine whether impacted stands are being reduced below

acceptable stocking levels or are only being thinned. Frequently, individual bears can

be removed to alleviate a serious damage problem.

Management methodsHunting and snaring are the most effective management methods now available. The

effectiveness of these methods in reducing damage to young trees is not fully known,

but population reduction usually will reduce damage to an acceptable level. There

are no current data to support supplemental feeding as a method for reducing bear

damage to trees. It is not recommended by the U.S. Department of Agriculture,

APHIS-ADC.

Hunting-In damage areas, sport hunting for bears should be encouraged, because

it is a desirable use of the resource and can help reduce damage (see chapter 4).

Local newspaper and radio releases can be helpful in directing hunters to critical

areas. Maps showing damaged areas and the road system should be available to

inquiring hunters.

77

Borrecco, J.E.; Black, H.C. 1990. Animal damage problems and control activities on

National Forest System lands. In: Davis, L.R.; Marsh, R.E.; Beadle, D.E., eds.

Proceedings of the 14th vertebrate pest conference; 1990 March 6-8; Sacramento,

CA. Davis, CA: University of California: 192-198.

Boddicker, M. 1983. Bears. In: Timm, R.M., ed. Prevention and control of wildlife

damage. Lincoln, NE: University of Nebraska, Cooperative Extension: C-17 to

C-24.

Childs, T.W.; Worthington, N.P. 1955. Bear damage to young Douglas-fir. Note

113. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Forest and Range Experiment Station. 3 p.

Erickson, A.W.; Nellor, J.; Petrides, G.A. 1964. The black bear in Michigan. Res.

Bull. 4. East Lansing, Ml: Michigan State University, Agricultural Experiment

Station. 102 p.

Flowers, R.H. 1987. Supplemental feeding of black bear in tree damage areas of

western Washington. In: Baumgartner, D.M.; Mahoney, R.L.; Evans, J. [and

others], eds. Proceedings, symposium on animal damage management in Pacific

Northwest forests; 1987 March 25-27; Spokane, WA. Pullman, WA: Washington

State University: 149-153.

Glover, F.A. 1955. Black bear damage to redwood reproduction. Journal of Wildlife

Management. 19: 437-443.

Gourley, M.; Vomocil, M. 1987. Public involvement in a black bear damage control

program on private land. In: Baumgartner, D.M.; Mahoney, R.L.; Evans, J. [and

others], eds. Proceedings, symposium on animal damage management in Pacific

Northwest forests; 1987 March 25-27; Spokane, WA. Pullman, WA: Washington

State University: 149-153.

Jonkel, C.J.; Cowan, I.M. 1971. The black bear in the spruce-fir forest. Wildl.

Monogr. 27. Washington, DC: The Wildlife Society. 57 p.

Kanaskie, A.; Chetcock, J.; Irwin, G; Overhulser, D. 1990. Black bear damage to

forest trees in northwest Oregon 1988-1989. Pest Management Report 90-1.

Salem, OR: Oregon Department of Forestry. 34 p.

Lindzey, F-G.; Meslow, E.C. 1976. Population characteristics of black bears on an

island in Washington. Journal of Wildlife Management. 41(3): 408-412.

Maser, C. 1968. Black bear damage in Oregon. Murrelet. 48(2): 34-38.

Mason, A.; Adams, D.L. 1987. Black bear damage to thinned timber stands in

northwestern Montana. Western Journal of Applied Forestry. 4(1): 10-13.

Nelson, E.E. 1989. Black bears prefer urea fertilized trees. Western Journal of

Appplied Forestry. 4(1): 13-15.

Piekielek, W. 1975. A black bear population study in northern California. California

Fish and Game. 61: 4-25.

Poelker, R.J.; Hartwell, H.D. 1973. Black bear of Washington. Biol. Bull. 14.

Olympia, WA: Washington State Game Department. 180 p.

79
Resner, O-L. 1953. Damage to conifers by bear. In: Proceedings, 33d annual

conference, Western Association of State Game and Fish Commissioners; 1953

June 1-3; Long Beach, CA. [Location of publisher unknown]: [Publisher unknown]:

109.

Rogers, L.L. 1986. Effects of translocation distance on frequency of return by adult

black bears. Wildlife Society Bulletin. 14: 76-80.

Rogers, L.L. 1987. Effects of food supply and kinship on social behavior, movements, and population growth of black bears in northeastern Minnesota. Wildlife

Monographs. 97: 1-72.

Scheffer, T.H. 1952. Spring incidence of damage to forest trees. Murrelet. 33(3):

38-41.

Schmidt, W.C. 1987. Bear damage-a function of stand density in young larch

forests. In: Baumgartner, D.M.; Mahoney, R.L.; Evans, J. [and others], eds.

Proceedings, symposium on animal damage management in Pacific Northwest

forests; 1987 March 25-27; Spokane, WA. Pullman, WA: Washington State

University: 145.

Schmidt, W.C.; Gourley, M. 1992. Black bear. In: Black, H.C., tech. ed. Silvicultural

approaches to animal damage management in Pacific Northwest forests. Gen.

Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station: 309-331. Chapter 15.

Small Mammals

Shrews (Sorex spp.)

Description-Shrews are mouse-sized

insectivores with dark beady eyes. Ears are

concealed or nearly concealed by soft, thick fur.

Shrews differ from mice, with which they often

are confused, by having five toes on each foot.

Mice have only four toes on each front foot.

Field identification among species is difficult.

Economic significance-Shrews are among

the many small forest mammals that eat conifer

tree seeds. Shrews destroyed up to 10 percent

of white spruce seed over a 6-year period in Alberta (Radvanyi 1970). Shrews also

ate lodgepole pine seeds there (Radvanyi 1977). More studies are needed to

determine the effects of shrews on reforestation.

Life History InformationPreferred habitat-Several species of shrews occur on Forest Service lands. They

prefer moist sites with an abundant food source and dense cover and are most

abundant in mesic forested regions.

Feeding habits-Shrews feed primarily on the adults and larvae of insects, other

small forms of animal life, and carrion when available, although seeds and other

plant parts also are eaten. They have both a voracious appetite and a rapid rate of

metabolism; they will starve if deprived of food for more than a few hours.

Activity--Shrews are active throughout the year. They spend most of their time

under cover and may be active either day or night.

80
Reproduction--Shrews do not breed until their second year. They usually have two

litters of four or five young each per year.

Damage problems and their managementIdentification-Damage by shrews has not been studied extensively. A trapline

survey is the best way of determining shrew occurrence.

Determining the need for damage management-Shrews should be considered as

potential seed eaters and included with the small rodents when considering the need

to protect seed.

Management methods-None known. Snap traps baited with peanut butter may be

used to collect shrews. Pit traps (large cans sunk into the ground until the lip of the

can is level with the ground) usually are more effective.

ReferencesHooven, E.F.; Hoyer, R.F.; Storm, R.M. 1975. Notes on the vagrant shrew, Sorex

vagrans, in the Willamette Valley of western Oregon. Northwest Science. 49(3):

163-173.

Ingles, L.G. 1961. Home range and habitats of the wandering shrew. Journal of

Mammalogy. 42(4): 455-462.

Jameson, E.W., Jr. 1955. Observations on the biology of Sorex trowbridgii in the

Sierra Nevada, California. Journal of Mammalogy. 36(3): 339-345.

Kangur, R. 1954. Shrews as tree-seed eaters in the Douglas-fir region. Res. Note 17.

Salem, OR: Oregon State Board of Forestry. 23 p.

Moore, A.W. 1940. Wild animal damage to seed and seedlings on cut-over Douglasfir lands of Oregon and Washington. Tech. Bull. 706. Washington, DC: U.S. Department of Agriculture, Bureau of Biological Survey. 28 p.

Radvanyi, A. 1970. Small mammals and regeneration of white spruce forests in

western Alberta. Ecology. 51: 1102-1105.

Radvanyi, A. 1977. Lodgepole pine seed depredation by small mammals in western

Alberta. Forest Science. 17: 213-217.

Schmidt, R.W. 1984. Shrew damage and control. In: Decker, D.J., ed. Proceedings,

1st Eastern wildlife damage conference; 1983 September 27-30; Ithaca, NY.

Ithaca, NY: Cornell University, Cooperative Extension Service: [pages unknown].

West, S.D. 1992. Seed-eating mammals and birds. In: Black, H.C., tech. ed. Silvicultural approaches to animal damage management in Pacific Northwest forests.

Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research Station: 167-186. Chapter 8.

81
Moles (Scapanus spp) Description-Moles live most of their lives

underground. Their small, pinhead-size eyes

are adapted to poor light. Broad front feet, with

palms usually facing outward, aid moles in

burrowing through the soil. Ear openings are

completely covered by thick, soft fur.

Economic significance-Moles often are

more of a nuisance than an economic liability.

The most serious problems occur in nursery beds, home yards, gardens, and golf

courses where they do extensive burrowing and mound building in their search for

earthworms and grubs. They may directly damage tree roots, their burrowing

activities may result in root desiccation, or their mounds may cover small seedlings.

Life historyPreferred habitat-Moist soils, lawns, fields, and forest areas where soil can be

easily worked.

Feeding habits--The major items in the diet of moles are earthworms, grubs,

beetles, and other insects. Small amounts of plant material, including rootlets, are

occasionally consumed.

Activity--Moles are active day and night, year-round. Peak periods of mound building

occur in late winter and early spring, and also in the fall, when young disperse and

establish new burrow systems.

Reproduction--Breeding occurs in February to March, with young born in March and

April. One litter is raised yearly, with two to six young per litter.

Damage problems and their managementIdentification-The mounds and shallow tunnels of moles are readily noticeable

whenever they are present. The mole creates a rounded soil mound by shoving excavated dirt up through the center of the mound. See chapter 2 for the key features

differentiating mole hills and gopher mounds.

Determining the need for management-Control of problem individuals is the best

approach. Preventive management is generally not recommended, as it can be time

consuming and expensive, whereas individuals can be removed with minimal effort.

Management methodsBaiting-No baits are registered for use in the control of moles on National Forest

System lands.

Trapping-Trapping is the most reliable method of control. Several types of mole

traps are available at hardware stores and nurseries. Most mole traps are designed

to be activated by a mole pushing aside an obstruction in a main runway of its

burrow system. Trap sites should be selected by locating areas of recent activity,

then stamping down short sections of the runway to determine if it is still being

actively used. Main tunnels probably will be repaired within a day. The shallow

feeding tunnels that branch from the deeper main tunnel frequently are not reused

and should not be used for trap locations. Best results are obtained by setting traps

only in actively used main tunnels (see fig. 25).

82
Figure 25--Scissors-jaw trap set in a main mole runway. The position of the jaws and

the dirt plug under the trigger are shown.

Fumigants-There are several fumigants registered for use in controlling moles (see

chapter 4). In general, the use of fumigants has given undependable results. The

variability of soils, soil moisture, burrow depth, and burrow length combine to make

the use of fumigants difficult and questionable.

ReferencesCaslick, J.W.; Decker, D.J. 1981. Controlling wildlife damage in homes and

gardens. Info. Bull. 176. Ithaca, NY: New York State College of Agriculture and

Life Sciences, Cornell University. 28 p.

Giger, RD. 1965. Home range, dispersal, homing and density of the Townsend mole

Scapanus townsendii (Bachman) near Tillamook, Oregon. Corvallis, OR: Oregon

State University. 63 p. M.S. thesis.

Kuhn, L.W. 1970. Mole control. In: Dana, R. H., ed. Proceedings, 4th vertebrate pest

control conference; 1970 March 3-5; Sacramento, CA. Davis, CA: University of

California, Cooperative Extension: 71-76

Pedersen, R.J. 1963. The life history and ecology of Townsend’s mole, Scapanus

townsendii (Bachman), in Tillamook County, Oregon. Corvallis, OR: Oregon State

University. 60 p. M.S. thesis.

Quilliam, T.A., ed. 1966. The mole; its adaptation to an underground environment.

Journal of Zoology. 149(1): 31-114.

Schaefer, V.H. 1982. Movements and diet activity of the coast mole Scapanus

orarius. Canadian Journal of Zoology. 60(3): 480-492.

Yates, T.L.; Pedersen, R.J. 1982. Moles. In: Wild mammals of North America:

biology, management, and economics. Baltimore, MD: Johns Hopkins University

Press: 37-51.

83
Rodents in

Campgrounds

An excellent reference on the problems that rodents and other kinds of wildlife may

create in campgrounds, diseases that may be involved (primarily plague), and practical control measures is Marsh and others (1981). It deals mainly with California species, but has an extensive list of general references. As pointed out in the report, the

establishment of campgrounds may result in high densities of rodents through provision of extra water, food, and burrowing sites. When rodent densities are high, the

stage may be set for epizootic disease (a disease attacking a large number of animals simultaneously). The integrated management plan proposed includes sanitation,

changes in the design of facilities, and other suggestions. Rodent population-reduction

methods and ectoparasite control methods also are discussed.

Managers should remain current on wildlife diseases and epizootics specific to their

areas. Consult with public health officials and local veterinarians for updated local

information. Wild birds are reservoirs for viral encephalitis; rodents and lagomorphs

for plague and tularemia (their ticks are carriers for Rocky Mountain spotted fever).

Beavers are suspect in spreading human giardiasis; woodchucks and deer spread

parasites pathogenic to domestic livestock; waterfowl contaminate bathing beaches

with “swimmers’ itch,” and Cuterebra bots (larvae of bot flies) of- pets are normally

parasites of rodents and rabbits (Georgi 1983). Lyme disease, carried by deer ticks,

is now a concern nationwide.

ReferencesGeorgi, J.R. 1983. Parasites of wildlife transmissible to domestic animals and man.

In: Decker, D.J., ed. Proceedings, 1st Eastern wildlife damage conference; 1983

September 27-30; Ithaca, NY. Ithaca, NY: Cornell University, Cooperative

Extension Service: 97.

Marsh, R.E.; Salmon, T.P.; Howard, W.E. 1981. Integrated management of rodents

and other wildlife in campgrounds. Rep. 81-39. San Francisco, CA: U.S.

Department of Agriculture, Forest Service, Pacific Southwest Region, Forest Pest

Management. 126 p. [Available from: Cashier, State of California, Department of

Food and Agriculture, 1220 N. Street, Sacramento, CA 95814. Ask for Sale

Publication 521 and remit $5.00 for each copy.]

Salmon, T.P.; Gorenzel, W.P. 1981. Plague, what you should know about it. Leafl.

Uinta Ground Squirrel

(Spermophilus richarsonl)

21233. Berkeley, CA: University of California, Division of Agricultural Science. 14 p.

Description--Uinta ground squirrels are medium-sized rodents. The middle of the

back is brownish. The tail is black mixed with buffy white above and below; belly

hairs are tipped with pale buff.

Economic significance--Uinta ground squirrels are usually of only minor concern in

reforestation programs, but they feed on emerging pine seedlings and young trees

when other food becomes scarce.

Life history informationPreferred habitat-Meadows, grasslands, and forest openings are the most suitable

habitats.

Feeding habit-spring and early summer foods consist mainly of roots, grasses,

legumes, and a wide variety of succulent plants. Some insects also are taken. In late

summer, ripening seeds and grains are taken in abundance. Food is not stored.

84
Activity--These ground squirrels normally enter hibernation in late summer or early

fall, as soon as they have accumulated sufficient body fat. Older males enter hibernation between late July and early August. Young animals require much of their food

for growth, and some may be found aboveground as late as mid-September. Emergence takes place in February and March, after from 5 to 7 months of hibernation.

Ground squirrels are relatively short-ranging animals and may spend their entire life

in a very small area.

Reproduction-Breeding takes place shortly after spring emergence from

hibernation. Young are born in 24 to 30 days and leave the nest in 2 to 3 weeks.

Litters average from five to seven young.

Damage problems and their managementIdentification-Uinta ground squirrels are active during daylight hours. Their burrow

entrances and adjacent soil mounds are readily apparent.

Determining the need for damage management-Squirrel control may be needed

to protect new grass seedlings, if an old meadow area is heavily populated. Ground

squirrels are seldom a problem on forest land, unless it has been deforested for

several years and squirrels are common where trees are planted.

Management methodsBaiting-Aboveground uses of strychnine-treated baits are no longer registered for

ground squirrel control on National Forest System lands. Contact pesticide-use

specialists in District, Forest, or Regional offices, or APHIS-ADC, for the current

status of aboveground uses of strychnine and other toxicants for use in ground

squirrel control.

Habitat manipulation-There is a direct relation between ground squirrel numbers

and range condition. Poor vegetative conditions usually provide more desirable

squirrel habitat because of decreased plant density and a greater variety of plant

species available. Improving poor range conditions through management often will

reduce the density of ground squirrels.

Trapping--Use no. 0 jump traps, live-traps, or no. 120 Conibear traps (see

chapter 4). Trapping of individuals is effective and highly selective. Trapping should

be used only for localized problems, because it is time consuming and costly.

Hunting--Where it can be used safely, a .22 caliber rifle is suitable for shooting

ground squirrels, and it may be used effectively as a control measure within localized

areas.

Fumigants-Fumigants may be effective in reducing ground squirrel populations

(see chapter 4).

ReferencesRecord, C.R. 1983. Franklin, Richardson and Columbian ground squirrels. In: Timm,

R.M., ed. Prevention and control of wildlife damage. Lincoln, NE: University of

Nebraska, Cooperative Extension Service: B-133 to B-139.

85
Belding (Oregon) Ground

Squirrel (Spermophilus

Description-Belding ground squirrels (left

be/ding) and Columbian

in the illustration) are medium-sized and

Ground Squirrel

have grayish upper parts mixed with buffy

(Spermophilus

white. A brownish streak may run down the

columbianus) back. The tail is reddish beneath, tipped

with black and bordered with buff or white

and is small and relatively flat.

The larger Columbian ground squirrel (right)

may be distinguished from all other species

within its home range by its mottled, gray

upperparts and dark rufous feet and legs.

Economic significance-Belding and

Columbian ground squirrels are usually of

only minor concern in reforestation programs, but they do feed on emerging pine

seedlings and young trees when other food is scarce.

Life history informationPreferred habitat-Belding ground squirrels range east of the Cascade Range in

Oregon. Columbian ground squirrels are found in eastern Washington and northeastern Oregon. Meadows, grasslands, and openings in or along the edges of ponderosa pine, Douglas-fir, and larch stands are the most suitable habitats.

Feeding habits-spring and early summer foods consist mainly of green vegetation,

including grasses, legumes, and a wide variety of succulent plants. Some insects

also are taken. In late summer, ripening seeds and grains are taken in abundance.

Food is not stored.

Activity--These ground squirrels begin hibernation in mid-summer to early fall. Older

males enter hibernation between late July and early August. Young animals may be

found aboveground as late as mid-September. Emergence takes place in February

and March. Ground squirrels are short-ranging animals and may spend their entire

lives in small areas.

Reproduction--Breeding takes place shortly after spring emergence. Young are born

in 24 to 30 days and leave the nest in 2 to 3 weeks. Litter sizes range from five to

seven.

Damage problems and their managementIdentification-These ground squirrels are active during daylight hours. Their burrow

entrances and adjacent soil mounds are readily apparent.

Determining the need for damage management-Squirrel control may be needed

to protect new grass seedlings if an old meadow area is heavily populated. Ground

squirrels are seldom a problem on forest land, unless it has been deforested for

several years and squirrels are numerous where trees are planted.

8 6
Management methodsBaiting-Aboveground uses of strychnine-treated baits are no longer registered for

ground squirrel control on National Forest System lands. Contact pesticide-use specialists in District, Forest, or Regional offices, or APHIS-ADC, for the current status

of aboveground uses of strychnine and other toxicants for use in control of ground

squirrels.

Habitat manipulation-There is a direct relation between squirrel numbers and range

condition. Poor vegetative conditions usually provide more desirable squirrel habitat,

because of decreased plant density and the greater variety of forbs available.

Improving poor range conditions through management often will reduce destructive

concentrations of ground squirrels.

Trapping-Use no. 0 jump traps, live traps, or no. 120 Conibear traps. Trapping of

individuals is an effective and highly selective control method. Trapping should be

used only for localized problems because it is time consuming and costly.

Hunting-Where it can be used safely, a .22 caliber rifle is suitable for shooting

squirrels, and it can be used effectively as a control measure within localized areas.

Fumigants--Fumigants may be effective in reducing ground squirrel populations in

localized areas.

ReferencesBoag, D.A.; Murie, J.O. 1981. Population ecology of the Columbian ground squirrel

in southwestern Alberta. Canadian Journal of Zoology. 59(12): 2230-2240.

Manville, R.H. 1959. The Columbian ground squirrel in northwestern Montana.

Journal of Mammalogy. 40(1): 24-45.

Record, CR. 1983. Franklin, Richardson and Columbian ground squirrels. In: Timm,

R.M., ed. Prevention and control of wildlife damage. Lincoln, NE: University of

Nebraska, Cooperative Extension Service: B-133 to B-139.

Turner, L.W. 1972. Habitat differences between Spermophilus belding and

Spermophilus columbianus in Oregon. Journal of Mammalogy. 53: 914-917.

Golden-Mantled Ground Description-The golden-mantled ground

Squirrel

( Spermophilus lateralis)

squirrel, which looks something like a chipmunk, .

has a relatively short, straight tail. The head is

copper colored, and white stripes bordered with

black are on each side of the back. The lack of

stripes on the sides of the face and its much

larger size distinguishes it from the chipmunks.

Economic significance-Golden-mantled

ground squirrels consume large quantities of

both coniferous seed and emerging seedlings.

They do the most destruction to forest

regeneration in some areas of any of the ground squirrels.

These ground squirrels behave much like chipmunks, adapting easily to human

presence and becoming quite tame. Their appearance and mannerisms also make

them a very attractive part of the natural environment.

87

ReferencesGordon, K.L. 1943. The natural history and behavior of the western chipmunk and

the mantled ground squirrel. Studies in Zoology 5, Monographs. Corvallis, OR:

Oregon State University. 104 p.

Hooven, E.F. 1966. Pine regeneration in Oregon, habits and control of seed-eating

mammals. Res. Pap. 5. Corvallis, OR: Oregon State University, Forest Research

Laboratory. 24 p.

McKeaver, S. 1964. The biology of the golden-mantled ground squirrel. Ecological

Monographs. 34(4): 383-401.

Mullally, D.P. 1953. Hibernation in the golden-mantled ground squirrel, Citellus

lateralis bernardinus. Journal of Mammalogy. 34(1): 65-73.

Salmon, T.P.; Lickliter, R.E. 1984. Wildlife pest control around gardens and homes.

Pub. 21385. Berkeley, CA: University of California, Cooperative Extension. 90 p.

Storer, T.I.; Evans, F.C.; Palmer, F.G. 1944. Some rodent populations in the Sierra

Nevada of California. Ecological Monographs. 14(2): 165-192.

Tevis, L., Jr. 1955. Observation on chipmunks and mantled squirrels in northeastern

California. American Midland Naturalist. 53(1): 71-78.

Wirtz, J.H. 1961. The golden-mantled ground squirrel Citellus lateralis chrysodeirus

(Merriam): its social and community interactions. Corvallis, OR: Oregon State

University. 134 p. Ph.D. dissertation.

Black-Tailed Prairie Dog

(Cynomys ludovicianus)

Description-These squirrellike rodents have short legs and tails. Hair color is sandy

brown to cinnamon, with lighter hair on the belly. Tail tips are black. Weights are up

to 3 pounds. These rodents get their name from their barklike calls.

Economic significance-prairie dogs cause extensive losses on National Grasslands by destroying high percentages of annual forage production. They may cause

an unwanted change in plant composition of pastures by removing favored grasses.

Their burrowing activities may create problems for mechanical cultivation and

harvesting and vehicle operation, and pose hazards for horses and other livestock.

Irrigated fields may be drained by burrowing activity. These animals may serve as a

reservoir for bubonic plague.

Life history informationPreferred habitat-prairie dogs prefer open areas of low vegetation (grasses or

shrubs) and may be especially numerous near water sources in arid areas.

Feeding habits--Prairie dogs eat the seeds, succulent leaves, stems, and roots of

grasses, sedges, and forbs. Grasshoppers and a variety of other insects are eaten

during summer.

Acfivity--These animals are active year-round.

Reproduction-One litter of four to eight young is produced each year.

69
Damage problems and their management-prairie dogs clip vegetation for food

and apparently to maintain open areas around their burrows. This may result in a

change in forage species composition. Managers should note, however, that these

changes may be beneficial to other wildlife species. Isolated or small colonies generally can be tolerated. When colonies cover several acres or more, particularly where

they adjoin managed private lands, controls may be necessary. Before controls are

planned, check the legal status of this animal in your area by consulting with local

state wildlife officials or APHIS-ADC personnel. Because the black-footed ferret is

listed as an endangered species and may occur within prairie dog range, special attention must be given to its possible occurrence.

Management methodsBaiting-Aboveground uses of strychnine are currently prohibited in most situations.

Contact pesticide-use specialists (District, Forest, or Region) or APHIS-ADC for the

current registration status of chemical toxicants for use in prairie dog control.

Habitat manipulation-Plow and leave lands fallow for 2 years, then plant tall grain

crops. Rest-rotation and light grazing can delay prairie dog reinvasion. Restoration of

degraded rangelands now occupied by high populations of prairie dogs offers the

optimum long-term solution to managing prairie dog “problems.”

Trapping-For small areas, up to 5 acres, trapping with leg-hold traps, live-traps, or

no. 120 Conibear traps may be effective; trapping on larger areas seldom is practical.

Hunting-Persistent shooting may reduce localized populations of prairie dogs by up

to 75 percent. Managed sport shooting is a potentially effective method of managing

prairie dog populations over wide areas.

Fumigation-Gas cartridges can be used for prairie dog control in some states.

Check with APHIS-ADC for restrictions, recommendations, and ordering information.

ReferencesBoddicker, M.L. 1983. Prairie dogs. In: Timm, R.M., ed. Prevention and control of

wildlife damage. Lincoln, NE: University of Nebraska, Cooperative Extension

Service: B-75 to B-84.

Clark, T.W. 1973. Prairie dogs and black-footed ferret in Wyoming. In: Proceedings,

black-footed ferret and prairie dog workshop; [dates of meeting unknown]; [location

of meeting unknown]. Brookings, SD: South Dakota State University: 88-101.

Gold, I.K. 1976. Effects of blacktail prairie dog mounds on shortgrass vegetation.

Fort Collins, CO: Colorado State University. 40 p. M.S. thesis.

Uresk, D.; Bjugstad, A. 1980. Effects of prairie dogs and cattle on vegetation of the

northern high plains-executive summary. In: Proceedings, 7th North American

prairie dog conference: [dates of meeting unknown]; [location of meeting unknown].

Springfield, MO: Missouri State University: [pages unknown].

U.S. Department of Agriculture. 1981. USDA summary report-strychnine, RPAR

DD 2/3. Washington, DC. 47 p.

90
Chipmunks

(Eutamias spp.)

Description-The chipmunk probably is the

most popular and well known squirrel

species. It can be identified easily by facial

stripes, which distinguish it from all other

mammals over most of its range. Side and

back stripes end at its reddish-colored rump.

Economic significance-Coniferous tree

seeds are a favorite food of chipmunks.

These seeds are eagerly sought after and

stored for winter use. Studies have shown

that chipmunks can consume more than 200

ponderosa pine seeds in one day of feeding.

When these animals are abundant, they have a deleterious effect on both natural

and artificial seeding. Most seed stored by chipmunks is in deep caches and, even if

uneaten, few seeds will grow.

Life history informationPreferred habitat-Chipmunks occupy nearly all forest and range lands.

Feeding habit-Principal foods are flowering plant and tree seeds, grasses,

berries, roots, and insects. Large quantities of seeds are stored in deep underground

burrows to provide food during winter.

Activity--Chipmunks are terrestrial but climb readily when alarmed or when

searching for food. Activities are confined to daylight hours. Nests are usually underground, near the base of a stump or beside a rock or log. These animals are most

active during spring, summer, and fall. They hibernate in winter but wake occasionally

to eat from stored food and to make short excursions from their dens.

Reproduction-Breeding occurs once a year, usually in March or April. The

gestation period is 28 to 30 days, and litters range from four to six.

Damage problems and their managementIdentification--Trapline surveys and general observations give a good indication of

chipmunk occurrence (fig. 27).

Determining the need for damage managmement-Chipmunks should be considered with deer mice when determining rodent control or repellency needs for seed

protection. Clipping of emergent seedlings occurs but has not been shown to be a

serious problem.

Management methods-Control may be needed when populations are high in

reforestation project areas scheduled for seeding. Control is most effective in spring

and early fall. Spring control primarily protects emerging seedlings. Early fall control

will help protect the seed during the period when it is normally collected and stored

by chipmunks.

Baiting--Anticoagulants (chlorophacinone, diphacinone, Pival, and Warfarin) are

registered only in California for control of chipmunks (and golden-mantled ground

squirrels).

Trapping--Trapping with Sherman-type live-traps or leg-hold traps is an effective

means of controlling chipmunks within a localized area.

91

Tree Squirrels: Douglas

Squirrel or Chickaree

(Tamiasciurus douglasii),

Western Gray Squirrel

(Sciurus griseus), and

Red Squirrel

(Tamiasciurus hudsonicus)

Description-Douglas squirrels and red

squirrels are also known as “pine squirrels.”

The Douglas squirrel (pictured) is slightly

smaller than the red squirrel; head and body

length of the Douglas squirrel is 6 to 7 inches.

The vocal Douglas squirrel is a dark, reddisholive color, with a yellowish or rusty belly.

Distinct black lines along each side, which

develop during the summer, help distinguish it

from the western gray squirrel. The western

gray squirrel is silvery gray in color with white

underparts and has a very bushy tail edged

with white.

The bushy-tailed red squirrel is widespread throughout most of the pine, spruce, and

mixed hardwood forests of North America. It usually is heard before it is seen,

because of its noisy, ratchetlike call. Its color is uniformly yellowish or reddish with

seasonal variations, including a paler back color during winter and a black line

running down each side in summer. It is the smallest tree squirrel in its range; head

and body length is 7 to 8 inches.

The western gray squirrel is found along both sides of the Cascade Range in western

Washington and western Oregon, in the Coast Range, and along the Sierra Nevada

in California. This species commonly inhabits oak groves of the interior valleys. It is

much larger (about 22 inches long, including tail) than the Douglas squirrel or red

squirrel. It may cause minor, localized damage to mast crops in mixed coniferousdeciduous forests. Bark stripping in the upper boles of conifers is a much greater

problem, however.

Economic significance-squirrels may be serious nuisances in seed orchards, seed

production areas, cone storage facilities, trees with artificially pollinated cones, or

conifer stands designated for cone collection because tree squirrels cut immature

cones. However, cone cutting and caching also provides a source of seed that may

be readily collected by humans. Squirrels also may place considerable stress on

ponderosa pine through defoliation (Soderquist 1987). They eat conifer buds and

inner bark from shoots; they also may clip terminal and upper lateral shoots and may

strip bark from the upper boles of trees to feed on exposed sapwood.

Life history informationPreferred habitat-Tree squirrels occupy all coniferous forest types throughout their

ranges. The western gray squirrel also commonly inhabits oak groves of the interior

valleys.

Feeding habits-seeds, berries, nuts, buds, mushrooms, and insects are eaten

when available. Large quantities of food are stored, and single caches may contain

up to 10 bushels of cones. When feeding on cones, tree squirrels habitually return to

a favorite log or low limb, eventually creating a large “midden” pile of discarded cone

scales.

93

lndividual free protection--Bands of sheet metal flashing will prevent squirrels from

climbing trees. The bands should be at least 2 feet wide and should be placed 6 feet

above the ground. Branches of protected trees should not be adjacent to unprotected

trees.

Trapping-Individual squirrels can be readily trapped with a live-trap, size 0 jump

trap, or a Conibear size 110 trap, using walnut meats for bait. Trapping requires skill,

experience and considerable time for baiting, setting, and checking traps. Trapping is

practical only where a few squirrels are to be removed.

Baiting--No poison baits are registered for control of tree squirrels.

Hunting-Where legal and safe, using a .22 rifle or shotgun is a practical method of

population reduction.

ReferencesAdams, L. 1955. Pine squirrels reduce future crops of ponderosa pine cones.

Journal of Forestry. 53: 35.

 Baldwin, R.J.; Howard, W.E.; Marsh, R.E. 1987. Debarking of conifers by the

western gray squirrel (Sciurus griseus). In: Richards, C.G.J.; Ku, T.Y., eds. Control

of mammal pests. London: Taylor and Francis Ltd: 45-54.

Finley, R.B., Jr. 1969. Cone caches and middens of Tamiasciurus in the Rocky

Mountain region. Misc. Publ. 51. Lawrence, KS: University of Kansas, Museum of

Natural History: 233-273.

Fisch, G.; Dimock, E., Il. 1978. Shoot clipping by Douglas squirrels in regenerating

Douglas-fir. Journal of Wildlife Management. 42(2): 415-418.

Jackson, J.J. 1983. Tree squirrels. In: Timm, R.M., ed. Prevention and control of

wildlife damage. Lincoln, NE: University of Nebraska, Great Plains Agricultural

Council and Cooperative Extension Service: B-141 to B-146.

McKeever, S. 1961. Relative population of small mammals in three forest types of

northeastern California. Ecology. 42(2): 399-402.

McKeever, S. 1964. Food habits of the pine squirrel in northeastern California.

Journal of Wildlife Management. 28(2): 402-404.

Shaw, W.T. 1936. Moisture and its relation to the cone-storing habit of the western

pine squirrel. Journal of Mammalogy. 17(4): 337-349.

Soderquist, T.R. 1987. The impact of tassel-eared squirrel defoliation on ecotonal

ponderosa pine. Journal of Mammalogy. 68(2): 398-401.

Sullivan, T.P. 1992. Tree squirrels, woodrats, and beaver. In: Black, H.C., tech. ed.

Silvicultural approaches to animal damage management in Pacific Northwest forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 271-287. Chapter 13.

Timm, R.M., ed. 1983. Prevention and control of wildlife damage. Lincoln, NE:

University of Nebraska, Cooperative Extension Service and Great Plains

Agricultural Council.

Walters, J.; Soos, J. 1961. Douglas squirrel damage to Douglas-fir. Res. Note 32.

Vancouver, BC: University of British Columbia, Faculty of Forestry. 2 p.

95
Pocket Gophers

(Thomomys spp.)

Description-There are three genera of

pocket gophers in the United States. The

distinguishing characteristics of all pocket

gophers are the external cheek pouches that

open on either side of the mouth, and lips

that close behind large yellow incisors.

Consistent with a burrowing mode of life,

they have long, curved front claws. Size is

extremely variable in pocket gophers with

combined head and body length ranging from 5 to 9 inches. The size of pocket

gophers seems related to the vegetative community, locality, altitude, and latitude of

their habitat; males generally are heavier than females.

Only two age-class distinctions can be made in the field: juveniles (less than 1 year

old) and adults (1 or more years old). Juveniles are noticeably smaller and have

smaller reproductive organs.

Similar species-Ground squirrels are sometimes called gophers in local expression,

but pocket gophers are most often confused with moles. The following tabulation

shows the differences distinguishing pocket gophers from moles.

Pocket gophers Moles

Large yellow incisors No incisors

Blunt snout, small eyes Long snout, no apparent

and ears eyes or ears

Cylindrical, winter Tunnels form low surface

“casts,” aboveground ridges

Fan-shaped mounds, dirt Circular mound plug near

“plugs” near edge center

Life history-An evaluation of pocket gopher damage requires a clear understanding

of resource management goals and objectives and how gophers may affect those

objectives. If their activities are interfering with management objectives, damage

evaluation must begin with a knowledge of the animal; how to identify it and its

characteristics and behaviors, and how its populations increase and decrease.

Reproduction-Usually, only one litter is produced per year in the northern part of

their range, but two litters per year are common in southern parts of their range.

Breeding usually occurs in early spring but may occur at any time in the southern

parts of their range. After a gestation period of about 18 days, a litter of four to eight

young is born in the burrow system of the female and reared by her for about 40

days. The juveniles then disperse and establish their own burrow systems. Burrowing

through snow facilitates pocket gopher dispersal.

96
Population Cycles-Pocket gopher populations are dynamic and exhibit random

fluctuations. Gopher numbers continue to increase until an imbalance occurs between

the population level and the capacity of the habitat to support it. During the annual

cycle, pocket gopher populations generally peak at a high level between August and

October and then begin to decline until spring, when the population is increased by

the young. The population is comprised of up to 75 percent juveniles. The range of

fluctuation that populations undergo can be dramatic. Densities have been recorded

as high as 62 per acre.

Natural limiting factors that regulate pocket gopher populations include predation,

weather, food and cover, and to some extent, gopher territoriality.

The major predators of gophers include weasels, coyote, bobcat, badger, great

horned owl, barn owl, hawks, and snakes. Dispersing juveniles have the greatest

vulnerability to predators because they spend more time traveling aboveground.

Predation, however, serves more to slow the rate of increase than to prevent the

population from peaking.

The greatest influence of weather on gopher populations occurs in winter and late

spring and relates to the amount of snowfall received. An extremely deep snowpack

with a high water content results in high mortality of both adults and newborn young,

particularly when the snow melts rapidly and saturates the ground with water, which

floods the burrows. Too little snowfall results in even higher gopher mortality,

because most forest and range soils percolate ground water rapidly and the soil

freezes solid without the insulating effects of deep snow. Pocket gophers may freeze

in their burrows under these conditions.

Gophers are herbivorous and highly adaptable in their feeding habits. The relative

abundance and quality of forage and the amount and type of habitat available directly

correlates with the density of pocket gophers in a particular area. The territorial size

of individual gophers depends on habitat conditions, and because these territories

are aggressively protected, only a limited density within a given area will occur.

The maximum life span of pocket gophers is about 5 years; few gophers live beyond

2 years, however. Juveniles (less than 1 year old) have the highest mortality rate in

pocket gopher populations, and winter mortality of all age groups takes the greatest

toll.

Habitat characteristicsWant community types-Pocket gophers are remarkably adaptable and occupy a

wide range of plant communities from sea level to over 10,000 feet in elevation. The

communities most preferred by gophers are those supporting an understory of

relatively lush stands of fleshy-rooted forbs or rhizomatous sedges and, to a lesser

extent, grasses. Rangelands, meadows, clearcut areas, burn areas, and open

coniferous forests are the most desirable sites, if adequate soil depth for burrowing is

present. Plant community types can be stratified to determine the risk of pocket

gopher damage (Volland 1974). Some of the factors enhancing the selection of a site

by pocket gophers are the palatability of the vegetation, the associated plant species

or the combination of plant species occurring in the area, the climate and topography

of the area, and the seral stage of the plant community; for example, whether it is a

herbaceous community or a shrub community.

97
Grass seeding on disturbed sites in Idaho (Green and others 1987) significantly

delayed natural succession, thereby resulting in high pocket gopher populations

Soil conditions--Because pocket gophers live underground in burrows, soil characteristics also help determine pocket gopher habitat preference. Burrow systems usually are located in friable, light-textured soils with good drainage, poor water-holding

capacity, and high porosity. Clay soils, soils with a depth of less than 6 inches, soils

with a shallow water table, and soils that are continuously wet are unfavorable for

pocket gopher burrowing. Pocket gophers tend to use soils with a moisture range up

to 50 percent.

Pocket gopher burrow systems provide shelter and access to forage. Each adult has

its own burrow system covering an area of about 0.02 to 0.1 acre. The systems

consist of runways 4 to 48 inches below the ground surface. Side tunnels from the

main runways are used as exits and for deposition of soil, debris, excess food, and

feces. Larger chambers are used for nest sites and food storage. Tunnels are from 2

to 3 inches in diameter. Feeding tunnels are shallow, normally 2 to 8 inches below

the surface, and are most extensive in areas where vegetation is sparse.

Food caches are maintained near nest chambers, and shallow underground food

caches also are located 3 to 4 inches below the ground in lateral chambers loosely

plugged-off from the main burrow system. Large amounts of plant materials may be

stored.

The burrow system is a closely regulated microenvironment, and a gopher will

generally plug any openings in the system within 48 hours-often within 24 hours or

less.

By building, maintaining, and living in burrow systems, pocket gophers leave three

types of physical signs on the surface of the ground that are visible in the snow-free

period: mounds, winter soil casts, and tunnel entrances that gophers have plugged

with soil (known as soil plugs).

The typical horseshoe-shaped mounds pushed up by gophers are the result of soil

excavated as they extend and repair their burrow systems. Mound building is most

common in late summer and fall when juveniles are establishing burrow complexes

and older animals are enlarging burrow systems.

In winter in the northern parts of their range, gophers extend their burrow systems

into the snow, apparently to facilitate their search for food. Later, excess soil is

pushed into these snow burrows to create the ribbonlike “winter casts” that become

evident as the snow melts. These winter casts can indicate where damage might

occur, if suitable conditions are present.

Soil plugs are more difficult to detect. They are small circles of disturbed soil at the

ground surface or a small circular depression toward the edge of a mound. These

usually are formed where gophers have emerged to forage and plugged the hole

upon reentry. Vegetation may be clipped around soil plugs. In spring, soil plugs and

winter casts may be the only soil indicators of current pocket gopher activity.

9 8
Feeding habits-pocket gophers are herbivorous mammals and use all portions of

plants in their diet. Roots, stems, leaves, and bark (chewed from woody species) provide forage for gophers. Because of their burrowing habits, roots are readily available,

but pocket gophers also make openings from their tunnels and forage for food and

nest material aboveground. In some instances, they have been observed pulling

entire plants down through the soil into their burrows. Barking and clipping of shrubs

and trees occurs aboveground, especially under snow in winter.

Forbs are the most preferred food plants of pocket gophers. Grasses are also used

and may constitute a major component of the gopher’s diet in winter. The outer bark

and roots of woody species are used by gophers in winter, when other fresh vegetation is sparse, and in summer and fall when other vegetation is drying up and roots

are being collected for food caches.

The habit of storing food in underground caches may account for the harvest of considerably more vegetation than is actually eaten. Roots constitute the major portion of

the forage collected for food caches.

Damage problems and their evaluationForest lands-pocket gopher damage to forest crops was first reported in the early

1900s, but it did not become a serious reforestation problem until the 1950s. This

increased importance is the result of intensified management and of recognition that

gophers are responsible for some damage previously attributed to porcupines, mice,

squirrels, livestock, and unknown causes.

Increases in pocket gopher problems and subsequent damage are directly related to

the opening up of timber stands through harvest, insect and disease losses, or wildfires that result in a flush of seral vegetation (forbs and grasses). Gophers, normally,

are widely but sparsely distributed in timber stands, and are primarily concentrated at

sites where preferred ground vegetation provides ample forage; for example, river

banks, spring areas, meadows, and other breaks in the forest canopy. Dense brush

areas often produce low food volumes, which limit gopher populations on those sites.

In the Nez Perce National Forest, Idaho, severe site disturbance in 1986 resulted in

increased pocket gopher activity: the number of mounds ranged from 300 per acre

on minimally disturbed, broadcast-burned sites to more than 6,000 per acre on

severely disturbed areas where slash had been piled by bulldozer (Boyd 1987). The

practice of grass seeding on disturbed sites significantly delayed natural succession,

thereby resulting in higher gopher populations and increased seedling mortality.

Substantial gopher populations can become established in 2 to 3 years when a low

residual population is present on or near a cutover area. The current reforestation

policy is to plant or seed as soon as possible after harvest treatment. This allows

tree seedlings to develop into larger, less susceptible sizes, as the gopher population

is expanding. If small, slow-growing conifers are planted where gopher populations

are high, the trees are subject to severe damage and mortality in the first 3 to 5 years

after planting. A second advantage of rapid reforestation is the reduced competition

for available soil moisture by the seedlings, often resulting in higher seedling survival

rates.

99
Heavy pocket gopher infestations in regeneration areas have commonly resulted in

seedling losses of 20 to 30 percent and, occasionally, up to 70 percent in 1 year.

Losses of seedlings due to pocket gopher damage in regeneration areas usually continue over a period of years, so that what may appear as acceptable yearly gophercaused seedling mortality is actually, in a cumulative respect, excessive.

Damage identification--The two most common types of tree damage by gophers are

root pruning and a combination of stem barking and clipping. Stems of small seedlings (basal diameters of 1/2 inch or less) often are cut into two or more sections.

Seedlings frequently are clipped at or near ground level and the roots or stems are

taken. Gophers may pull entire seedlings into their burrow systems, which leaves no

evidence of damage other than missing seedlings. If seedlings are missing, suspect

gopher or elk damage. Root pruning and barking of small seedlings occur year-round

but are most frequent in winter.

Root pruning on larger seedlings and saplings also occurs year-round. The seasonal

frequency has not been determined, primarily because damage generally does not

become evident until long after the trees have been injured. Some trees also incur

damage over a period of several years. Characteristic indicators of root-pruned trees

include shortened needles, premature needle drop, shortened internodes, and overall

poor development.

Clipping and barking on larger trees occur primarily underground or aboveground

under snow cover. This damage is more prevalent in areas where heavy snowpacks

persist or food quantity is short. Girdling is often complete and leaves white stems

easily seen in spring.

Other types of tree damage caused by gophers include root exposure by burrowing

and burying of seedlings by winter casts or mounds. Root exposure occurs most

often in conjunction with root gnawing and barking. It is usually of minor importance

in comparison with other types of damage. Damage from winter casts or mounds

deposited on small planted or natural seedlings is a common occurrence in areas of

high gopher density and may injure or kill seedlings.

Rangelands--Damage by pocket gophers to rangelands differs with livestock use

and condition of the range. In the past, much time, effort, and money were spent for

pocket gopher control on rangelands in poor condition. Pocket gopher control is

seldom economically feasible on poorly managed rangelands or those in fair or better

condition.

Soil erosion-Pocket gopher activity can accelerate soil erosion in some areas

depending on slope, soil type, and the action of water. Tunnel collapse and water

running through burrows may intensify already existing erosion potentials.

Dams and dikes-Pocket gopher activity can affect dams and dikes by weakening

their structural design or decreasing their water-holding capacity.

100
Damage surveys-There are three methods of surveying pocket gopher activity and

relative abundance. The purpose of the survey determines which method is used.

The first, the reconnaissance survey, evaluates the presence or absence and relative

numbers of pocket gophers. This method is used to determine the extent of pocket

gopher damage potential and usually is initiated when a timber management proposal

entails some form of regeneration harvesting as an alternative. The second type, the

gopher-mound survey, determines the level of gopher activity in an area and provides

an indication of gopher abundance. Its main purpose is to determine the location and

extent of gopher control needs. The last method, the open-burrow survey, evaluates

the effectiveness of baiting or trapping as a control technique.

Reconnaissance survey--This survey is usually a part of another examination, such

as a timber sale reconnaissance. The primary purpose is to determine if an active

gopher population exists in the area, and if so, the extent and relative size of the

population,

Information on gophers is collected at each plot, when a timber-sale planning or other

survey is being conducted. The presence of recent mounds (mounds formed during

the year) or winter casts are primary indicators of gopher presence.

If a joint silviculture examination and gopher reconnaissance survey reveals moderate

gopher activity on 50 percent of a planned timber sale area and if the silvicultural

prescription developed for the area calls for a regeneration harvesting method, the

reforestation portion of the prescription should consider the following issues: the type

of regeneration that will occur; the ease with which it will be obtained; the amount

that could be lost to gophers; and the effect of timber harvesting on the population of

gophers present at the site. These data and the information obtained during the

gopher reconnaissance will allow the consideration of silvicultural alternatives and

alert the land manager to assess possible treatment or control alternatives, before

the project’s implementation.

Gopher-mound survey-An indication of the pocket gopher population level and

extent of control needs can be obtained with a gopher-mound survey. This survey is

particularly useful when management alternatives are being considered, and it should

be conducted whenever gophers are a potential problem. It often is conducted as part

of another survey, such as a stocking survey.

The gopher-mound survey determines the percentage of an area that has current

gopher activity by using the presence of recent mounds (mounds formed during the

year) to determine the approximate size and distribution of the population. The percentage of plots with sign is used as an index to population density and as a basis

for determining control needs.

Standard plot size should be 1/100 of an acre or 11.8-foot radius. Plot sizes differ if

they are part of another survey being conducted simultaneously.

Minimum sampling intensity should not be less than that of the associated survey, or

5 percent of the area. The number of plots and their distribution should be sufficient

to determine the location of gopher population centers, the approximate number of

mounds per acre, and the range in numbers over the area. (Counting the number of

mounds may not provide better information than simply determing the presence or

absence of fresh gopher activity on the sampling plots.) These data will provide the

bases for determining control needs, based on staff experience with local conditions.

101
The extent of the area affected and the number of mounds indicate the relative

feeding pressure by pocket gophers. Although food habits differ by site and availability, the more gopher activity, the greater the potential for damage to conifer

seedlings.

Wherever pocket gophers occur, some damage and mortality of planted seedlings can

be expected. Temporary population reductions of pocket gophers in plantations are

probably needed if some or all of the following conditions occur:

. Percentage of active gopher plots exceeds 25 percent of 1/100-acre plots on

new plantations (0-2 years old) or 40 percent of 1/100-acre plots on established

plantations (3-5 years old).

l Current stocking level of seedlings is low or marginal, and additional

environmentally caused mortality can be expected.

l Trees are growing slowly and are less than 0.2 inch in caliper about 1 inch

above ground level.

. Number of active pocket gopher systems exceeds two per acre.

. Food supply of gophers will be significantly altered by herbicide or other

treatment, which will cause these animals to seek alternative food sources.

The gopher-mound survey and the above criteria should not be relied on as sole

determinants for implementing a control project. There also is need to evaluate actual

losses occurring in a plantation. The same densities of pocket gophers in different

habitats with different seedling sizes, survival rates, and other variables will result in

different impacts.

It is essential that local experience and conditions be considered in making the final

determination of the need for temporary population reductions.

Open-burrow survey-The objective of this survey is to determine the reduction in

gopher activity that occurs after an operational control program.

Sampling points are established in an area before treatment. These should be at

least 100 feet apart and include recent (less than 1 week old) gopher activity.

A minimum of 40 sampling plots (or fewer on units of less than 10 acres) should be

used per treatment area. The plots need to be flagged and numbered to facilitate

resurveying. An active burrow system is opened on each plot having recent sign.

Twenty-four to 48 hours later, the area is revisited and notation is made on whether

the opened burrows were plugged or remained open. A survey after 48 hours is preferred by some experienced biologists. Repeat the survey 7 to 14 days after a control

treatment. If the direct control operation was successful, there should be significantly

fewer plugged burrows found during the second survey.

Biologists believe that a reduction in activity of at least 80 percent is needed to accomplish a significant reduction in damage. Areas with less than an 80-percent reduction in activity should be considered for retreatment; baiting techniques and other

operational conditions should be analyzed to ensure that control activities are

optimum.

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Methods of damage management-The history and current status of pocket gopher

damage to conifers in western forests are well documented (Borrecco and Black

1990, Crouch 1986). At the present time, direct control of damaging gophers, primarily

by baiting or trapping, is the most widely used approach to alleviating pocket gopher

damage. in the future, integrating indirect or ecological control to reduce the habitat

suitability for gophers with direct control practices may prove to be more effective

and less costly.

Indirect control by habitat manipulation-Indirect control to limit damage to

seedlings by pocket gophers is accomplished by reducing habitat suitability, providing

alternate (buffer) forage, or by silvicultural modifications, including planting additional

seedlings.

Herbicide applications-Treating an area with selective herbicides can be done to

reduce the availability of gopher foods. Vegetation management with herbicides,

principally to control perennial grasses and forbs, can result in reduced gopher

numbers and may improve conifer survival by decreasing competition for moisture by

other vegetation. Herbicide treatment to control gophers requires a broader area of

coverage than does site preparation, and it is recommended that the planting of conifer seedlings be delayed for one winter between herbicide treatments and reforestation, to allow time for a sufficient reduction in the gopher population. It also prevents

the gopher population (at the pretreatment level) from being sustained by a primary

food source of planted seedlings.

Numerous herbicides are available for such use. The type of herbicide, the timing of

application, and the method and rate of application depend on the chemicals considered, their selective toxicity, and label requirements. Identification of the plants or

plant types being used as a food source will help indicate the herbicide needed.

Herbicides need to control the food source and, with the large number of approved

chemicals and the continual changes in these chemicals, recommendations should

be obtained from specialists at either the National Forest or the Regional Office.

The response of pocket gophers to herbicide treatments will differ with the type of

herbicide application, because the impact of the herbicide on gopher foods depends

primarily on the composition and density of the pretreatment vegetation. Because of

their highly selective toxicity, some herbicides may cause little change, as gophers

may switch to less desirable vegetation for food.

Although selective herbicide treatments show a potential to promote the survival and

growth of conifer seedlings and make habitats less favorable for pocket gophers, the

effectiveness of this method to reduce damage has not been widely studied. On

herbicide-treated sites, the seedlings may be better able to sustain minor damage by

gophers, and a reduction in gopher numbers usually leads to a reduction in gophercaused seedling mortality.

A disadvantage of herbicide treatments involves the possible adverse effects on the

food and cover plants used by other wildlife species. Abrupt alterations in the vegetative density and composition of an area can have a significant impact. In most

cases, the impact on other wildlife is temporary, because the changes in vegetation

are normally of short duration. Before herbicide treatments are undertaken, an

evaluation of the importance of the treatment site to all wildlife should be completed.

103
Silvicultural modifications-Habitat alteration by modifying silvicultural practices

has great potential for effective, long-lasting control through preventive management.

Emmingham and others (1992), for example, found that the use of the shelterwood

regeneration method, in place of clearcuting, creates less favorable habitats for

gophers and reduces damage to developing stands. In many instances, gopher damage could be avoided or reduced through early recognition of the animal’s probable

response to habitat changes resulting from silvicultural treatments.

Protecting conifers is difficult on a plantation densely populated with gophers. Recruitment of animals from inside or outside the plantation boundaries tends to maintain

the habitat at or near its carrying capacity. Rather than waiting to confront the problem under these conditions, a logical alternative is to anticipate the potential damage and attempt to prevent the population buildup that causes it.

Temporary buffer strips-In this method, an uncut strip of timber, 500 feet wide (or

wider), is left between logged units and gopher-populated areas (Barnes 1974). Meadows, open stands, or any area with abundant food supplies adjacent to harvest units

should be checked for presence of gophers. Buffer strips represent a temporary measure and essentially delay the invasion of gophers into harvested areas (unoccupied

or only sparsely occupied by gophers), thereby reducing the potential for damage to

seedlings. This delay can be useful, because in some areas where sufficient natural

regeneration can be obtained, even moderate pocket gopher populations will not

pose a problem.

In some situations, buffer strips are most effective when used in combination with the

direct control methods of baiting or trapping. The need for direct control before harvest is obvious where a reservoir of gophers occurs within a planned harvest unit.

Direct control in buffer strips is also necessary, if substantial gopher populations are

present in these strips. Where leaving strips of standing timber is not practical; direct

control in stands adjacent to gopher-occupied areas or along plantation boundaries

will have a buffer-strip effect and should be considered before logging.

Site preparation-Site preparation, in general, is beneficial to tree growth and

survival, but the effect of site preparation on seedling survival and growth (and on

associated vegetation) must be reviewed in relation to pocket gopher population

responses and damage. Site preparation techniques that disturb large amounts of soil

should be used as little as possible in areas prone to pocket gopher damage. This

practice may result in rapid invasion of pocket gophers from adjacent populated

areas, or an increase in breeding success by established gophers. Newly disturbed

soil often allows gophers to move rapidly underground. Gophers use disturbed soil

along roads and terraces to travel up to 1 mile or more. (On private forest lands in

south-central Oregon, intensive, large-scale site preparation with large, tractor-drawn

Rototillers, combined with herbicide treatments to control the recovery of herbaceous

vegetation, decimated resident pocket gopher populations for a sufficiently long period

to enable successful regeneration.)

Highly disturbed soils created by plowing, discing, or machine planting often predispose seedlings to gopher damage by creating a nearly readymade burrow system.

Gophers follow these readymade burrows, gathering food as they go.

Limited site preparation is a damage control measure that can be used to deter the

distribution of gophers. Site preparation with selective herbicides also may be an

extremely useful technique (see above).

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Stage-overstory removal--The harvest method selected in a potential area of pocket

gopher damage also can be a control measure. The relation of tree crown-cover to

herbage production indicates that clearcutting results in the best conditions for pocket

gopher invasions, establishment, and population increases. Partial cutting in certain

conifer stands minimizes the increase of the understory vegetation due to continual

partial shading, retains conifer reproduction in the understory (which is usually past

the stage most susceptible to pocket gopher damage), and results in minimal soil

disturbance. Depending on the habitat type, such an alteration generally supports

fewer gophers than does a comparable clearcut site. On some sites, however, natural

regeneration after partial cutting is unsuccessful because of factors other than gophers, but gopher populations build rapidly and may be mistakenly blamed for regeneration failure. Shelterwood cutting and underplanting shelterwood units, for example,

reduced pocket gopher damage to pine plantations in eastern Oregon (Emmingham

and others 1992).

Stage-overstory removal and the vegetative communities created must be carefully

analyzed, as many timbered types do not readily lend themselves to this silvicultural

treatment. The treatment also may not be compatible with stand composition

requirements.

Early planting--Planting should occur as soon as practicable after harvest. Waiting

longer than 1 year to begin reforestation allows an increase in food supplies for

gophers, and this often results in higher overall population levels. It usually takes 2 to

3 years after a timber harvest for significant increases in herbaceous vegetation to

occur and for pocket gophers to establish a population level detrimental to seedling

survival. Planting immediately after harvest will give seedlings a head start.

Size of planting stock-Large planting stock (2-1 or 3-O) is less susceptible to gopher damage than are small-sized seedlings. Seedlings less than 1/2 inch in caliper

width are commonly clipped by gophers, especially in winter where feeding takes

place under snow. Larger diameter seedlings may be chewed but may not be completely girdled. Also, large-caliper stems are seldom bent or pinned down in the snow

by the formation of winter casts. Such activity normally leads to misshapen trees.

Direct population control-Direct control techniques include hand- and machinebaiting, trapping, and use of individual tree protectors. Choice of these methods

should be based on site characteristics, season, available labor, economic considerations, and local experience.

Trapping-Several types of traps are available for controlling pocket gophers, although the Macabee kill-trap is probably the most popular. Trapping has been used

on forest lands to a limited extent. It is extremely slow and time consuming and is

practical only in small areas, in high-value situations such as nurseries or experimental areas, or as a supplement to other forms of damage control. Consequently, there

are few forest situations where trapping is feasible. This method is, however, of value

as a way to estimate population densities.

Trapping procedures are as follows:

1. Select an area with recent mound-building activity.

2. Open the lateral runway with a trowel.

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3. Set a gopher trap and insert it, prongs forward, well back into the burrow (fig. 29).

If the lateral runway is very short, the main runway often will be exposed during excavation. In that case, a trap should be set in each arm of the main burrow.

4. Secure traps with a light chain or wire and pin.

5. Leave entrance hole open to attract the gopher.

6. Mark each trap spot with flagging so that it can be relocated easily.

7. When trapping is done in spring, traps should be reset after a catch is made

because a burrow system may have more than one occupant at that time.

Baiting--Hazards to nontarget animals have been evaluated (Barnes and others

1985, Evans 1987, Fagerstone and others 1980). Baiting by hand or machine is a

much faster operation than trapping and is safe and effective when done properly.

But it usually requires one or more annual followup treatments. The number of

baitings and their frequency differs from area to area. Initial control success, tree

damage, vegetative conditions, and potential for reinvasion are among factors to be

considered. Baiting should be done during periods of greatest local mound-building

activity; using larger baiting crews for shorter periods often is advisable.

Hand-baiting requires three steps: location of a runway by probing or excavation;

placement of the toxic bait in the burrow by hand, spoon, or other appropriate means;

and covering the exposed burrow. Hand-baiting by spoon or bait dispenser may be

useful for gopher control on small acreages or steep terrain with isolated populations,

or to maintain control over low populations to restrict their dispersion into unoccupied

or sparsely occupied habitats. This method is particularly useful in treating peripheral

populations or spot-treating populations before they build.

I

Figure 29 -Trap placement for pocket gophers.

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Effectiveness of hand-baiting can be checked readily by an open burrow survey. If the

burrow systems are still occupied, they usually will be closed within 48 hours. Activity

checks should not be made until bait has been exposed for 2 weeks.

Strychnine-treated oats is currently the bait of choice for pocket gopher control; zinc

phosphide also is registered for this purpose. Anticoagulant baits are registered for

pocket gopher control in some states. Check with your wildlife biologist, Regional

pesticide-use specialist, or APHIS-ADC regarding the status of bait registrations and

control recommendations.

Hand baitinq-Any site regularly occupied by pocket gophers may be hand-baited,

but there are several conditions that influence control effectiveness:

. Active mound building must be taking place, to allow best selection of spots to

bait. Fresh mounds can be identified by their unweathered appearance and loose

horseshoe shape. Recent mounds often will be darker than surrounding soil

because of their higher moisture content.

l Soil moisture and soil type should be such that burrow crumbling does not occur

when probing or excavating tunnels for baiting. Moisture content becomes less

critical in soils that are well structured, fine textured, or heavily sodded. Granitic

soils and sandy soils are extremely difficult to probe; suitable moisture conditions

are required during the operation.

l Guidance of experienced baiters is necessary to ensure correct bait placement.

l The number of available baiters must be sufficient to permit complete and careful

coverage of the area requiring protection within a reasonable time. This often

becomes a problem on large areas.

Probing (with bait dispensers)--Probing is the most commonly followed method of

hand-baiting. It is the fastest hand-baiting technique but requires considerable

knowledge of gopher habits to be done effectively.

Expertise in using the probe is gained mainly through experience and self-training.

The first step is to check a spot near a fresh gopher mound for the presence of a

burrow. The probe then is pushed gradually into the ground at that spot. If the choice

is correct, a sudden release of pressure will be felt when the probe enters the burrow.

Initial attempts at probing should be verified by digging out the lateral and part of the

main runway. In this way, errors can be quickly corrected.

The following sequence should be followed when baiting with a probe:

1. Select an area with recent mound-building activity.

2. Locate the main runway by probing a lateral runway to its junction with the main

runway. Laterals usually join a main run within 2 feet or less. One or two test

probes down each arm of the main runway to form a rough "T” will verify the

location of the runway. Main runways also may be located by the presence of

small convex earth plugs. The plugs are made when gophers close their burrows

after returning from surface excursions. A probe can be made directly adjacent to

the earth plug, as the main runway is often immediately below.

3. Enlarge a probe hole in the main runway to accept the bait, but be careful to avoid

making a deep hole in the bottom of the burrow.

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4. Drop 1 teaspoonful of strychnine-treated oats into the burrow. Most baiting operations will require from 1/2 to 1 pound of strychnine-treated oats per acre.

5. Carefully cover all probe holes with clods, bark, stones, or other suitable material,

to prevent light or dirt from entering the burrow system, Covering the probe holes

also will reduce the chance of nontarget wildlife eating the bait. If the holes are left

open, gophers may push the bait aboveground while closing the holes, thereby

possibly exposing the bait to nontarget species.

6. Bait two spots in what appears to be the active working area of a single gopher.

7. Mark treated areas with plastic flagging. This will prevent confusion and facilitate

inspections.

Excavating-Opening main runways with a garden trowel (excavating) is a positive

method of locating good baiting spots. The only disadvantage is that it is relatively

slow. Excavating is an excellent way to study the arrangement of the burrow systems

of gophers and, in this respect, serves as a useful tool for training inexperienced

baiters to use a probe. One or two days of burrow excavation before advancing to a

probe will help ensure good control results.

The baiting procedure is very similar to that followed in the probing technique, except

that the hole is opened to allow bait placements. Follow the steps outlined for hand

baiting with a probe.

Machine-baiting procedures-An improvement over hand-baiting is the mechanical

bait dispenser-it is faster and just as efficient. This device allows an operator to

intersect runways and deposit bait in the same operation. With this device, 1 acre per

hour can be treated. The Forestland Burrow Builder provides an effective means of

controlling pocket gophers within limits determined by slope, surface and subsurface

obstructions, soil texture, and soil moisture. Soil conditions must be suitable for

preparing and maintaining a burrow. Excessively dry or coarse-textured soils do not

allow this to occur.

The machine creates an artificial burrow and at the same time deposits small

amounts of strychnine-treated oat bait. (A Rhoplex-binder added to this bait allows

the oats to flow smoothly from the hopper of this machine.) Gophers locate the new

burrows and eat the deposited bait within a few days. Maximum control usually is

achieved within 7 to 10 days after treatment. The machine can be used to treat 2-1/2

to 6 acres per hour. The crew includes a tractor operator and bait checker.

Machine-baiting has been shown repeatedly to be cost-effective in controlling pocket

gopher damage, especially on large plantations. It is currently the most widely

followed method of controlling gopher damage, but treatment must be done correctly

to assure effectiveness, and even successful baiting provides only temporary relief.

This is an important concept, because tree protection may be necessary for several

years, depending on the rate of tree growth. Complete population reductions rarely if

ever occur, and offspring of survivors may quickly repopulate unoccupied burrow

systems. In many areas, rapid invasion from adjacent, uncontrolled populations also

can be expected. An abundance of unoccupied systems likely will increase survival

of dispersing young, and reduced population densities may temporarily stimulate

reproduction and survival.

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Use of the burrow builder on forest lands introduces additional factors not encountered with hand-baiting. The artificial burrows may persist for several years, and the

possibility that they may facilitate reinvasion should be considered. One of the most

critical factors governing the use of the burrow builder is soil moisture. In dry climates,

where most gopher-reforestation problems occur, use of the machine often is restricted to short periods in spring and fall. Moisture requirements usually can be met

in spring, but the potential for reinvasion will necessitate fall treatment in most cases.

Fall moisture is unpredictable, and at higher elevations may first appear in sufficient

quantity as snow. The necessity of last-minute scheduling places an added burden

on management.

Environmentalconsiderations-Strychnine-treated oat bait is sold by the Pocatello

Supply Depot, USDA-APHIS, 238 E. Dillon, Pocatello, ID 83201. Strychnine-treated

bait placed belowground is effective only for a limited time, ranging from 1 week to

1-112 months, depending on soil moisture and other factors. Strychnine does not accumulate in the body, and it may be consumed at very low dosages over prolonged

periods with little or no ill effects. Ingestion of extremely high doses may cause immediate sickness and death in many animals. Sublethal doses may cause bait aversion. In some cases, animals may excrete low dosages of the poison through normal

metabolism.

Small mammals that readily eat the bait, such as ground squirrels, can be killed in

treatment areas (Anthony and others 1984). Secondary hazards to predators that feed

on gophers appear to be greatly lessened by the tendency of gophers to die underground (Barnes and others 1985). Studies by the EPA and the U.S. Fish and Wildlife

Service of strychnine baiting for gopher control found very minor losses to other than

the target species when bait was correctly placed. Most of these losses were to

burrowing animals intercepting burrows or using food found underground. Secondary

poisoning may occur only from ingestion of material stored in the gophers’ cheek

pouches. In response to a question on whether grizzly bears (an endangered species)

would be affected by strychnine baiting for pocket gopher control, the U.S. Fish and

Wildlife Service conducted research with radio-collared gophers in the Targhee

National Forest in Idaho (Barnes and others 1985). They concluded that carcasses of

gophers in baited areas did not pose a hazard. Also, grizzly bears were not likely to

consume lethal amounts of baits stored in gopher nests, although baits stored in

gopher food caches could present a risk.

Under the Endangered Species Act, the Forest Service must request formal consultation and a biological opinion from the U.S. Fish and Wildlife Service where management activities may affect an endangered species.

A formal consultation regarding the potential impact on grizzly bears of direct control

of pocket gophers by strychnine baiting resulted in a biological opinion. The opinion

requires that the following steps be taken before baiting for pocket gophers in grizzly

bear range:

l Use of strychnine baits is permitted in occupied grizzly habitats, with Regional

Forester approval.

. Presently, a review of Forest Service rodent control plans is required by the U.S.

Fish and Wildlife Service, where endangered species may be affected.

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. In grizzly bear range, a proposed treatment area is to be surveyed for grizzly sign

or grizzlies before control program is begun. If there is evidence that a grizzly is

physically present in the area, a strychnine-baiting program may not be initiated,

or if already begun, the program must be discontinued.

Strychnine and other chemicals used in various control operations are often misunderstood; an effective education program for the applicators and concerned publics will

be required. This program often needs to begin inside the Forest Service, so that

those most directly involved with the program understand and are committed to it.

In all suppression actions, direct or indirect, the program objective is to alleviate reforestation damage. The killing of individual animals is only one of many alternatives.

Managers should consider all options, and the benefits and costs of each. Direct

suppression through baiting is often the least suitable alternative in the long run.

Individual seedling protectors--Plastic-mesh tubing, such as Vexar, is an effective

but costly means of limiting gopher damage. Partially buried seedling protectors (to

protect both roots and stems) have reduced damage by 85 to 90 percent over 1 year.

In small reforestation areas exposed to heavy pocket gopher damage, seedling protectors can be cost-effective but are very labor intensive. Because of the labor

involved, costs for controlling gopher damage with this treatment may increase

planting costs by 50 to 150 percent.

In snow country, seedling protectors cannot be used on slopes greater than 25

percent without extensive maintenance, because snow movement frequently causes

terminal buds to grow through the plastic mesh, thereby distorting tree growth. Even

under optimal conditions, tubing often causes an excessive amount of distortion of

tree growth. Information is not available on the rate of breakdown of the tubing

underground and potential adverse impact on root growth. Seedling protectors (to

provide belowground protection), whether installed during planting or by prepacking

seedlings and protectors at the nursery, must be handled with great care to ensure

good seedling survival. For additional details see Campbell and Evans (1975; also

reprinted in appendix 3).

Prediction and prescription matrixEcological considerations-Management of animal damage is most effective when

based on sound ecological principles. The response of pocket gophers to timber harvest and reforestation is most influenced by the species of seral vegetation that

revegetate harvested sites, the composition and productivity of these plant communities, and the abundance of gophers or the proximity of populated areas before

harvest. All these factors may differ with habitat type, silvicultural method, and the

system of logging.

The habitat type classifies aggregates of land capable of producing similar plant communities at climax. Each climax plant community reflects the integration of environmental factors on the resultant vegetation. One habitat type may support a variety of

disturbance-induced, seral, plant communities. The classification of climax overstory

and understory vegetation is possible at any successional stage because this vegetative succession, anywhere within one habitat type, ultimately produces similar communities at climax.

110
Table 2-Options for controlling pocket gopher damage in relation to plant

community classes

Control option

Community class

Class l

a Class 2a

A B C A B C

Indirect:

Herbicide ? x x XP-F XF XF

Silvicultural methodShelterwood N/A N/A N/A X X X

Selection N/A N/A N/A X X X

Intermediate treatment N/A N/A N/A X X X

Size planting stock x x x x x x

Buffer strips N/A N/A N/A X X ?

Site preparationMechanicalb N/A N/A N/A X X X

Hand N/A N/A N/A N/A ? X

HerbicidesC

x x x x x x

Early planting x x x x

Direct:

?F

N/A

N/A

N/A

Baiting, hand and machine XP XP-F XP-F XF XF XF XF

Trapping ? N/A ? N/A N/A N/A X

Plastic tubes N/A X X X X X X

Monitor Primary

Class 3

N/A = not applicable; P = pretreatment; F = followup.

aClass 1 and 2 communities are further defined by the range within the classification.

Class 1A is the least typical of the type, with the lowest continuous gopher populations.

Class 1B is the most typical. Class 1C forms an intergrade between classes 1 and 2,

being more commonly like class 1 than 2. Class 2 has a similar classification system

(see text for details and examples).

bDozer stripping

C

Limit application, strip or spot

111
The variety of seral plants differs in composition, based on the habitat type, because

of the variation of environmental interactions and the ability of various plants to cope

with a given environment. This composition is predictable. The variation in the

makeup of a seral plant community affects the habitat suitability of each community

for gophers. A stratification of communities associated with habitat types can be used

to assess the risk of gopher damage when allocating or planning for resource uses

on a site. This determination will indicate where values and risks are the greatest.

Matrix development-The preference of pocket gophers for certain identifiable

habitat types suggests that communities may be grouped into three classes (table 2).

Class 1: Those communities having moderate to high incidence of gophers in natural

and disturbed stands.

Class 2: Those having a low incidence but a high potential for gopher occupancy.

Class 3: Those showing little observed gopher activity before and after activity or

disturbance at the site.

The understory vegetation provides the principal means of identifying and mapping

these communities, irrespective of their successional status. Consequently, expected

tree mortality and necessary gopher control measures can be planned before harvesting class 1 communities. Field identification of class 1 sites becomes important

in predicting postdisturbance infestation sources,

Class 2 communities usually support impoverished herbaceous understories in the

undisturbed condition. Burning or scarification will stimulate grass and forb production

up to 10 times pretreatment levels. The burst of food supply makes these communities attractive to scattered, onsite gophers or those populations from adjacent class

1 communities. For this reason, severe gopher damage within class 2 communities

usually is localized and must be treated as it occurs. In some areas, potential damage

has been reduced by leaving near-natural buffer strips between class 1 and 2 communities; this is a viable alternative.

Class 3 communities are dominated by shrubs that are not preferred gopher food.

Seral forbs created by disturbance seldom occur in this class. Once identified, little

consideration of gopher damage and control is necessary.

The classification of the habitat type or community as to class must be made at the

National Forest or Ranger District level and may be based on evidence or experience.

Some examples follow.

Class 1 communities often are open stands where herbaceous material is predominately fleshy-rooted forbs preferred by pocket gophers. In the Pacific Northwest,

examples are poorly stocked subalpine fir/elk sedge habitat type, predominated by

open-grown lodgepole pine, with clusters of lupine occurring throughout; mixed stands

of various conifers and aspen present; large volumes of fleshy-rooted forbs are common in the aspen areas.

112
Class 2 communities often are dense old growth or densely stocked small saw timber

or pole-size stands, with mostly dense sod-forming grasses. In some cases, these

may be lightly stocked and composed entirely of bunchgrasses with few forbs or other

vegetation present. When disturbed, dormant seed (soil-stored) will flourish, producing

abundant moderately to highly desirable forbs, shrubs, or grasses. Some examples in

the Pacific Northwest are Douglas-fir/pinegrass that has been harvested by using

various silvicultural systems with resultant fireweed, geranium, lupines, and pinegrass

producing abundant growth. Often roads and skid trails are present that produce

numerous annuals; ponderosa pine/bitterbrush habitat that has been lightly harvested

and disturbed often produces abundant forbs, especially lupine, or soil-stored forbs

with bulbous early growth characteristics.

Class 3 communities often are dominated by brush species that sprout, sucker, or

have root regenerating systems that allow rapid occupation of such areas by brush.

Brush communities that are sporadic in their occurrence or support both brush and

grass-herbaceous cover normally will be in class 1 or class 2 communities, depending

on the specific situation. Some changes in classification may occur because of silvicultural activities that affect the ability of an area to produce pocket gopher food

plants.

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census mountain pocket gophers in forest ecosystems. Journal of Wildlife

Management. 30: 327-334.

Teipner, C.L.; Garton, E.O.; Nelson, L., Jr. 1983. Pocket gophers in forest ecosystems. Gen. Tech. Rep. INT-154. Ogden, UT: U.S. Department of Agriculture,

Forest Service, Intermountain Forest and Range Experiment Station. 53 p.

Teitjen, H.P. 1973. 2,4-D, vegetation and pocket gophers. In: Turner, G.T.; Hansen,

R.M.; Reid, V.H. [and others], eds. Pocket gophers and Colorado mountain

rangeland. Bull. 554S. Fort Collins, CO: Colorado State University, Agriculture

Experiment Station. 90 p.

Volland, L.A. 1974. Relations of pocket gophers to plant communities in the pine

region of central Oregon. In: Black, H.C., ed. Proceedings, symposium on wildlife

and forest management in the Pacific Northwest; 1973 September 11-12;

Corvallis, OR. Corvallis, OR: Oregon State University: 149-166.

Beaver

(Castor canadensis)

Description-The beaver is the largest

rodent in North America, sometimes weighing

over 60 pounds. Its large size, flat scaly tail,

and webbed hind feet easily distinguish it from

other native mammals and from the nutria,

which is much smaller and has a round tail.

Beaver are golden to dark brown above,

somewhat lighter below.

Economic significance-Beavers were

eliminated from much of their former range

by over-trapping, but with proper management

they have become reestablished and are now common in many areas.

Beaver skins provide a minor source of income to some trappers. Most pelts are

used in Europe for making fur coats and hats and for trimming cloth garments.

115
Beavers are noted for their dam-building and tree-felling activities that have both

short- and long-term effects on the areas they occupy. Streams are slowed and

usually warmed, streamside shade is reduced, vegetative structure is changed, waterborne sediment is deposited in slack water of the ponds, stream courses are sometimes altered, and downstream flows are usually stabilized during the dry season.

Tree-cutting damage is usually of less importance than the damage produced by the

plugging of culverts and flooding of roads and timber stands as new ponds are

created. Tree cutting by beavers is usually a problem only when trees are removed

in campgrounds or scenic areas. Recent estimates of beaver flooding damage to

timber include $45 million in Georgia and $17 million in Mississippi (Robles 1987).

Life history informationPreferred habitat-water courses with aspen, willow, cottonwood and associated

streambank vegetation are the most suitable sites. Smaller streams with flows from

2 to 12 feet per second are very attractive to beavers.

Feeding habits-Bark, twigs, leaves, roots, and a wide variety of aquatic plants are

major food items. Cottonwood, aspen, and willow are the principal tree species

eaten. Conifers occasionally are eaten but are not a staple food.

Activity-Dam building and feeding occur primarily at night. Travel usually is

restricted to small areas around ponds or water courses. Young beavers dispersing

from colonies may travel many miles to find new habitat.

Reproduction-Beavers are polygamous and mate once a year in late January or

February. They are capable of breeding when 2 years old. From two to six kits are

born in April or May after a 3-month gestation period. The young remain as part of

the colony until 2 years of age, when they leave to establish their own homes.

Damage problems and their managementIdentification--Beavers can be identified by the presence of characteristic beaver

dams, conical stumps with prominent tooth marks, and large wood chips present

around stumps. Peeled sticks also may be present in or near water (fig. 30).

Determining the need for damage management-Beavers are valuable when their

activities can be tolerated. In considering the need and method of control, it should

be remembered that the ponds maintained by beavers generally have a high value

for recreation and as fishery and wildlife habitat.

Management methodsTrapping and shooting-Trapping is the most common method of removing

individuals, but shooting may be more effective. In both instances, results may be

only temporary, however. To remove problem beavers, get assistance from

APHIS-ADC, state wildlife biologists, or licensed private trappers. APHIS-ADC has

found that shooting by using a night scope is one of the most efficient, selective, and

expedient methods of removing nuisance beavers. Consult with state wildlife officials

regarding regulations pertaining to the taking of beaver by means of trapping or

shooting.

Fencing--A fenced lane can be constructed that will effectively discourage beavers

intent on plugging culverts or building dams in undesirable locations. (See chapter 4

for design of the beaver-baffler fence.)

116
Figure 30-Beaver damage showing typical conical-shaped stump (left), and peeled sticks with uniform horizontal toothmarks (right).

Tree guard-preventing beavers from damaging individual trees in areas such as

campgrounds requires intensive protective measures and continuous surveillance.

Individual trees can be surrounded by a sheet metal or 2- by 2-inch-wire fence built

from the ground to a height of 3 feet. Fencing may be ineffective in deep snow.

Explosives-Explosives have been used to rupture dams and drain water impoundments. Trapping usually precedes dam destruction. In Louisiana, where 117 beaver

dams were demolished with water gel explosives, researchers found that deep water

dams could be removed more effectively than shallow water dams, and that dams

removed in late summer were rebuilt less frequently than those removed in early and

midsummer (Dyer and Rowell 1985). Prompt draining of flooded timber land is

important, particularly during the growing season.

Plastic tubing-Plastic drainage tubing and wire mesh culverts have been used to

control water levels at nuisance beaver sites in New York (Roblee 1983). T-culvert

guards have also proven to be effective in recent trials (Roblee 1987).

The San Dimas Technology and Development Center, Pacific Southwest Region

(444 E. Bonita Avenue, San Dimas, CA 91173, phone 818/332-6231), has evaluated

methods of keeping beavers from building dams at culverts and developed a downspoutdesign showing great promise. Contact them for design details on downspouts,

perforated pipes, bafflers, and perforated culvert extensions. They are soliciting field

experience with these designs or other new concepts.

117
ReferencesAllred, M. 1981. The potential use of beaver population density in beaver resource

management. Journal of the Idaho Academy of Science. 17(1): 14-24.

Borrecco, J.E.; Black, H.C. 1990. Animal damage problems and control activities on

National Forest System lands. In: Davis, L.R.; Marsh, R.E.; Beadle, D.E., eds.

Proceedings, 14th vertebrate pest conference; 1990 March 6-8; Sacramento, CA.

Davis, CA: University of California: 192-198.

Bradt, G.W. 1947. Michigan beaver management. Lansing, Ml: Michigan Department

of Conservation, Game Division. 56 p.

Dyer, J.N.; Rowell, C.E. 1985. An investigation of techniques used to discourage

rebuilding of beaver dams demolished by explosives. In: Bromley, P.T., ed.

Proceedings, 2d Eastern wildlife damage conference; 1985 September 22-25;

Raleigh, NC. Raleigh, NC: North Carolina State University: 97-120.

Fisher, P.H. 1986. Keeping beavers from plugging culvert inlets. Engineering Field

Notes. Washington, DC: U.S. Department of Agriculture, Forest Service. 18: 9-13.

Fitzgerald, W.S.; Thompson, R.A. 1988. Problems associated with beaver in stream

or floodway management. In: Crabb, A.C.; Marsh, R.E., eds. Proceedings, 13th

vertebrate pest conference; 1988 March 1-3; Monterey, CA. Davis, CA: University

of California: 190-195.

Hill, E.P. 1982. Beaver (Castor canadensis). In: Chapman, J.A.; Feldhamer, G.A.,

eds. Wild mammals of North America: biology, management, and economics.

Baltimore, MD: Johns Hopkins University Press: 256-281.

Medin, D.E.; Torquemada, K.E. 1988. Beaver in western North America: an

annotated bibliography, 1966 to 1986. Gen. Tech. Rep. INT-242. Ogden, UT: U.S.

Department of Agriculture, Forest Service, Intermountain Research Station. 18 p.

Owen, C.N.; Adams, D.L.; Wigley, T.B. 1984. Inefficacy of a deer repellent on

beavers. Wildlife Society Bulletin. 12: 405-408.

Provost, E.E. 1958. Studies on reproduction and population dynamics in beaver.

Pullman, WA: Washington State University. 78 p. Ph.D. dissertation.

Roblee, K.J. 1983. The use of corrugated plastic drainage tubing and wire mesh

culverts for controlling water levels at nuisance beaver sites. In: Decker, D.J., ed.

Proceedings, 1st Eastern wildlife damage control conference; 1983 September

27-30; Ithaca, NY. Ithaca, NY: Cornell University, Cooperative Extension: 56-57.

Roblee, K.J. 1987. The use of T-culvert guard to protect road culverts from plugging

by beavers. In: Holler, N.E., ed. Proceedings, 3d Eastern wildlife damage control

conference; 1987 October 18-21; Gulf Shores, AL. Auburn, AL: Auburn University,

Cooperative Extension: 25-41.

Wigley, T.B., Jr. 1981. A model of beaver damage and control. State College, MS:

Mississippi State University. 151 p. Ph.D. dissertation.
Nutria (Myocaster copypu) Description-These semiaquatic rodents are native to South America. They

resemble beavers but have long round tails. Males sometimes weigh as much as 20

pounds, but most adults weigh about 8 pounds. Their hind feet are webbed between

the inner four toes.

Economic significance-Nutria may cause damage to newly planted cypress

seedlings and are a deterrent to natural regeneration of cypress in some flooded

areas of the Southeastern United States. They also may cause minor damage to

Douglas-fir plantations in western Oregon and Washington.

Life history informationPreferred habitat-Wetlands and flooded areas provide ideal habitat. Through

escape from fur farms and distribution by fur trappers, nutria have established

substantial populations in Oregon and Washington, North Carolina to Maryland, and

Alabama to Texas. Wild populations have been reported in at least 40 States.

Feeding habits-Nutria commonly feed on the basal parts of soft grasses or aquatic

plants. They may eat several pounds of food daily.

Activity--When alarmed on land, these animals splash into water and may remain

hidden in aquatic vegetation. Like muskrats, they build feeding platforms of discarded

plant parts. They may dig extensive burrow systems and are primarily nocturnal

animals.

Reproduction-Nutria breed throughout the year; litter size averages five young,

after a 130-day pregnancy. Newborns are fully furred, with their eyes open and can

swim immediately.

Damage problems and their management-Nutria have been damaging newly

planted cypress seedlings in Louisiana since the late 1940s. By 1960, the problem

was so serious that the USDA Soil Conservation Service recommended that further

plantings be suspended until a control method was available. In a 1985 test, plastic

seedling protectors were chewed through at the water level, the seedlings were

clipped and dropped and the taproots pulled out. The taproot bark and root collars

were eaten. All seedlings were destroyed within 8 weeks. Chickenwire fences provided excellent protection from nutria in dry areas. Individual wire tubes for use as

seedling protectors were found to be difficult to make and install.

Zinc phosphide is the only Federally registered toxicant for use in nutria control and

usually is used with fresh carrot bait, after prebaiting. Baiting procedures are difficult

and must be carefully followed for effectiveness and safety. Forest Service personnel

should consult with their wildlife biologist, Regional Office pesticide-use specialist, or

APHIS-ADC personnel for the latest control recommendations before initiating control

practices. In some states, nutria are protected furbearers; consult state wildlife

officials before initiating controls.

119
Meadow Voles

(Microtus spp.)

120

ReferencesConnor, W.H.; Toliver, J.R. 1987. The problem of planting Louisiana swamplands

when nutria (Myocaster coypu) are present. In: Holler, N.R., ed. Proceedings, 3d

Eastern wildlife damage control conference; 1987 October 18-21; Gulf Shores, AL.

Auburn, AL: Auburn University, Cooperative Extension: 42-49.

Evans, J. 1983. Nutria. In: Timm, R.M., ed. Prevention and control of wildlife damage.

Lincoln, NE: University of Nebraska, Cooperative Extension: B-61 to B-70.

Evans, J. 1987. Vexar seedling protectors did not reduce nutria damage to planted

bald cypress seedlings. Tree Planters Notes. 38(3): 26-29.

Willner, G.R. 1982. Nutria. In: Chapman, J.A.; Feldhamer, G.A., eds. Wild mammals

of North America: biology, management, and economics. Baltimore, MD: Johns

Hopkins University Press: 1059-1076.

Description-Meadow voles (also known as field

mice) are mostly brownish gray, with dense fur,

beady eyes, small ears, and relatively short tails.

The several species of meadow voles differ

widely in size; the combined length of their heads

and bodies ranges from 2 to 5 inches. Vole

presence is indicated by 1/2-inch-wide runways

through matted grass. Further evidence includes

small piles of droppings and short clippings of

grass along these runways. Lemmings, tree voles, and redback voles may

be confused with Microtus spp. Individual species coloration is the main

distinguishing factor.

Economic significance-Meadow voles eat conifer seeds, newly germinated seedlings, and bark of young trees. They can cause serious damage to conifer plantations,

especially where snow occurs in winter. Meadow voles also are detrimental to many

agricultural crops during periods when their populations are high.

Life history informationPreferred habitat-Meadow voles occur in a variety of sites with sufficient vegetation

to provide food and cover. Grassy areas provide the most desirable habitat.

Feeding habits-All types of vegetation, including grass, herbaceous foliage, twigs,

roots, seeds, and bark, are eaten.

Activity--Meadow voles are active both day and night throughout the year. Their presence is readily detected by distinct winding runways beneath the vegetation. Each

vole usually maintains its own set of runways, but its territory may be occupied by

several voles. Individual home territories range from a few square feet to areas as

large as 0.1 acre.

Damage problems and their managementIdentification-Barking of small limbs and seedlings is characterized by indistinct

tooth marks and a fuzzy, roughened appearance (fig. 31). Areas of dense ground

vegetation have numerous distinct runways.
Figure 31-Vole-barked seedlings showing typical roughened stem. 

Determining the need for damage management-Meadow vole populations fluctuate dramatically, often causing damage at high-population levels, with populations 

dropping after damage is noticed and before control is undertaken. When considering 

whether to undertake damage management, be sure to verify that a problem still 

exists, as the population can crash in a matter of weeks. 

Management methodsBaitineMeadow voles usually can be controlled with 2-percent zinc phosphidetreated grain. Distribute the bait in quantities of l/2 teaspoonful directly in runways 

and burrows. The quantity of bait needed per acre will differ depending on vole 

density and distribution and on the density of cover. 

Six pounds of bait per acre normally is enough to control high populations in dense 

cover. Correct bait placement is very important, as the voles seldom venture from the 

protection of their runways. Baiting is most effective in late fall. Baiting may be 

needed for several years in problem areas. 

Anticoagulants are registered for use in some states. Check with your wildlife biologist 

or Regional Office pesticide-use specialist to determine the status of toxicants 

registered in your area. 

Habitat man$u/atio+Removing food and cover is an effective method for controlling damage by meadow voles, but it may have adverse effects on other wildlife. 

This approach to damage control is most applicable in old fields and other areas 

having dense grass cover. Habitat manipulation can be accomplished most effectively 

by spraying with herbicides or by cultivation (both methods are especiallly appropriate 

for Christmas tree plantations). Mowing or grazing may be applicable in some 

situations. 

121 
ReferencesAskham, L.R. 1992. Voles. In: Black, H.C., tech. ed. Silvicultural approaches to

animal damage management in Pacific Northwest forests. Gen. Tech. Rep.

PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station: 187-204. Chapter 9.

Caslick, J.W. 1969. How to control mouse damage in conifers. In: The

Conservationist. Albany, NY: New York State Department of Conservation.

August-September: 28-29.

Caslick, J.W.; Decker, D.J. 1977. Control of wildlife damage in orchards and

vineyards. Info. Bull. 146. Ithaca, NY: New York State College of Agriculture and

Life Sciences, Cornell University. 18 p.

Caslick, J.W.; Eadie, W.R. 1969. Inexpensive bait stations for mouse control in tree

plantings. American Christmas Tree Journal. November: 19-20.

Gill, A.E. 1977. Food preferences of the California vole, Microtus caifornicus.

Journal of Mammalogy. 58(2): 229-223.

Goertz, J.W. 1964. Habitats of three Oregon voles. Ecology. 45(4): 846-848.

Jameson, E.W., Jr. 1958. The cost and effectiveness of controlling Mircrotus with

zinc phosphide. Journal of Wildlife Management. 22(1): 100-103.

Kartman, L.; Murray, K.R.; Prince, F.M. [and others]. 1958. Public health

implications of the Microtus outbreak in Oregon and California during 1957-58.

California Vector Views. 5: 19-24.

Oregon State University Cooperative Extension Service. 1959. The Oregon

meadow mouse irruption of 1957-1958; a collection of reports from several

agencies on various aspects of the irruption. Corvallis, OR: Oregon State College.

88 p.

Radvanyi, A. 1980. Control of small mammal damage in Alberta oil sands

reclamation and afforestation programs. Forest Science. 26(4): 687-702.

122
Deer Mouse 

(Peromyscus spp.) 

Description-Deer mice are the most widely 

distributed members of this genus. They are 

distinguished from other mice by large 

membranous ears. Color is yellowish brown to 

grayish above, with white or gray underparts; feet 

are white. The tail is sharply bicolored, white 

below and dark above. Total length is about 7 

inches; the tail is nearly half of the total length. 

Economic significance-Deer mice are considered the most devastating of the 

seed-eating rodents. Field studies have shown that they eat and cache large 

quantities of conifer seed and that even one or two mice per acre can seriously 

deplete natural seed fall or artificial seeding. 

Life history informationPreferred habitat-Deer mice occupy nearly all habitat types on forest lands. Their 

need for ground cover is not as critical as it is for meadow voles and shrews. Large 

numbers of deer mice are often found on burned areas, even though ground cover 

may be sparse. 

Feeding habits-Seeds, fruits, and insects provide the major sources of food. Coniferous seeds usually are readily accepted, especially seeds of Douglas-fir and pines. 

AcfMfpDeer mice are active throughout the year. They are primarily nocturnal. 

The average home range is about 4 acres. 

Reproducfiorr-Litter sizes range from three to seven, with an average of four litters 

each year. The gestation period is from 22 to 25 days. Young mice may breed when 

6 to 8 weeks old. Populations usually peak in autumn. 

Damage problems and their managementIdentification-Conifer seeds are eaten by gnawing a small irregular hole in one end 

or side of the hull and removing the endosperm (fig. 32). Deer mice often leave an 

empty boat-shaped hull with clean-cut edges at the opening. 

Figure 32-Douglas-fir seeds (left) and ponderosa pine seeds (right) opened by deer mice. 

123 
Determining the need for seed protection--Populations of small mammals normally

exceed the minimum density required to consume or cache most of the seed distributed in direct seeding. Density of deer mice alone is rarely below one per acre on

forest lands, which is sufficient to cause significant seed depredations (Hooven 1958,

Moore 1940). Thus, successful establishment of broadcast-seeded Douglas-fir is

unlikely, if the acceptance rate of seed spots (see chapter 3) exceeds 5 percent or

more of the seed spots in one night (Moore 1940).

Assuming that a 5-percent catch of seed-eating mammals is comparable to a

5-percent rate of seed-spot acceptance, seed protection would be required whenever

the catch on trapline transects (see chapter 3) exceeded 5 per 100 trapnights.

Management methodsSeed protection-Although once commonly used, no chemical treatments currently

are recommended. More tests are needed to determine whether supplemental

feeding at the time of conifer seeding might protect seeds until germination, as has

been shown for an initial g-week-test period in Canada (Sullivan and Sullivan 1982).

ReferencesAnthony, R.G.; Morrison, M.L. 1985. Influence of glyphosate herbicide on

small-mammal populations in western Oregon. Northwest Science. 59: 159-168.

Black, H.C. 1969. Fate of sown or naturally seeded coniferous seeds. In: Black,

H.C., ed. Proceedings, symposium on wildlife and reforestation in the Pacific

Northwest; 1968 September 12-13; Corvallis, OR. Corvallis, OR: Oregon State

University, School of Forestry: 42-51.

Black, H.C.; Hooven, E.F. 1974. Response of small-mammal communities to habitat

changes in western Oregon. In: Black, H.C., ed. Proceedings, symposium on

wildlife and forest management in the Pacific Northwest; 1973 September 11-12;

Corvallis, OR. Corvallis, OR: Oregon State University, School of Forestry: 177-186.

Borrecco, J.E.; Black, H.C.; Hooven, E.F. 1979. Response of small mammals to

herbicide-induced habitat changes. Northwest Science. 53: 97-106.

Gashwiler, J.S. 1967. Conifer seed survival in a western Oregon clearcut. Ecology.

48(3): 431-438.

Gashwiler, J.S. 1969. Deer mouse repopulation of a poisoned Douglas-fir clearcut.

Journal of Forestry. 67(7): 494-497.

Hooven, E.F. 1958. Deer mice and reforestation in the Tillamook Burn. Res. Note

37. Corvallis, OR: Oregon Forest Lands Research Center. 31 p.

Hooven, E.F.; Black, H.C. 1976. Effects of some clearcutting practices on

small-mammal populations in western Oregon. Northwest Science. 50: 189-208.

Jameson, E.W. 1952. Food of deer mice, Peromyscus rnaniculatus and P. boylei, in

the northern Sierra Nevada, California. Journal of Mammalogy. 33: 50-60.

King, J.A., ed. 1968. Biology of Peromyscus (Rodentia). Spec. Publ. 2. American

Society of Mammalogy. 593 p.

Lawrence, W.H.; Rediske, J.H. 1962. The fate of sown Douglas-fir seed. Forest

Science. 8: 210-218.

124
Pine Mouse

(Microtus pineto

Maguire, C.C. 1989. Small mammal predation on Douglas-fir seedlings in

northwestern California. Wildlife Society Bulletin. 17: 175-178.

Marsh, R.E.; Howard, W.E.; Cole, R.E. 1977. The toxicity of chlorophacinone and

diphacinone to deer mice. Journal of Wildlife Management. 41(2): 298-301.

Moore, A.W. 1940. Wild animal damage to seed and seedlings on cut-over

Douglas-fir lands of Oregon and Washington. Agric. Tech. Bull. 706. Washington,

DC: U.S. Department of the Interior. 28 p.

Piper, S.E.; Johnson, E. 1940. Some studies of Peromyscus and other rodents in

the San Bernardino Mountains of California, 1937 to 1940. California Department

of Agriculture Bulletin. 29(3): 131-145.

Sullivan, T.P.; Sullivan, D.S. 1982. Reducing conifer seed predation by use of

alternate foods. Journal of Forestry. 80(8): 499-500.

Radvanyi, A. 1970. Lodgepole pine seed depredation by small mammals in western

Alberta. Forest Science. 17: 213-217.

Radvanyi, A. 1970. Small mammals and regeneration of white spruce forests in

western Alberta. Ecology. 51: 1102-1105.

Ritchie, C.; Sullivan, T.P. 1989. Glyphosate treatment and deer mice in clearcut and

forest. Northwest Science. 61: 199-202.

West, S.D. 1992. Seed-eating mammals and birds. In: Black, H.C., tech. ed. Silvicultural approaches to animal damage management in Pacific Northwest forests.

Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research Station: 167-186. Chapter 8.

Williams, 0. 1955. Home range of Peromyscus maniculatus rufinus in a Colorado

pine community. Journal of Mammalogy. 36(1): 42-45.

Williams, 0. 1959. Food habits of the deer mouse. Journal of Mammalogy. 40:

415-419.

rum)

Although pine mice (also called pine voles) are not known to cause extensive damage

in tree plantations, they may damage or destroy seedlings in nurseries and have been

destructive in progeny tests in South Carolina. These mice girdle roots and tree

trunks. Where extensive damage occurs in National Forests, Regional Office approval

should be sought to try control methods used by apple orchardists. Bait stations made

of polyvinyl chloride (PVC) tubing, joined to form an inverted "7,” provide a practical

means of controlling voles in New York apple orchards during winter and spring.

ReferencesCaslick, J.W.; Eadie, W.R. 1969. Inexpensive bait stations for mouse control in tree

plantings. American Christmas Tree Journal. November: 19-20.

Tobin, M.E.; Richmond, M.E. 1987. Bait stations for controlling voles in apple

orchards. In: Holler, N.E., ed. Proceedings, 3d Eastern wildlife damage control

conference; 1987 October 18-21; Gulf Shores, AL. Auburn, AL: Auburn University,

Cooperative Extension: 187-195.

125
House Mouse

(Mus musculus)

Woodrats

(Neotoma spp.)

In storage structures, nationwide, house mice may seriously damage property and

they, or their parasites, may transmit several diseases to humans. Effective control

programs include rodentproof construction, sanitation, and direct population reduction

through the use of toxicants, traps, or glue boards,

Mouseproof construction includes sealing all openings 1/4 inch or larger in building

foundations and around service openings (pipes, wires, vents). Doors and screens

must fit tightly and be reinforced with sheet metal, where needed. Detailed instructions on rodentproofing are available from APHIS and the Cooperative Extension

Service.

Because 50 or more traps are needed in a medium-sized storage building to remove

an infestation of house mice, trapping is seldom practical. Glue boards exposed to

dusty conditions lose their effectiveness quickly.

In Forest Service storage facilities, anticoagulant baits exposed in bait boxes

(see fig. 11) usually are effective. Because house mice may travel only a few feet,

bait boxes should be no more than 10 feet apart. Careful attention to providing a

continuous supply of fresh, high-quality bait is needed.

ReferencesCaslick, J.W.; Decker, D.J. 1980. Rat and mouse control. Info. Bull. 163. Ithaca, NY:

Cornell University, Cooperative Extension. 22 p.

Salmon, T.P.; Lickliter, R.E. 1984. Wildlife pest control around gardens and homes.

Publ. 21385. Davis, CA: University of California, Cooperative Extension. 90 p.

Timm, R.M. 1983. House mice. In: Timm, R.M., ed. Prevention and control of wildlife

damage. Lincoln, NE: University of Nebraska, Cooperative Extension Service:

B-27 to B-44.

Description-Woodrats, otherwise known as

pack rats, often are confused with Norway rats.

Both the dusky-footed woodrat and the

bushy-tailed woodrat are easily distinguished from

the Norway rat by the woodrats’ soft, fine fur

covering the body. The dusky-footed woodrat also

has a hairy, unscaled tail. Woodrats have large

ears and usually have white feet and underparts.

Head and body length is 7 to 8 inches.

Economic significance-The dusky-footed woodrat occasionally strips bark from the

crowns of young conifers for nest material. This injury usually occurs in dense, 10- to

30-year-old stands and seldom is widespread. Both the dusky-footed woodrat and

the bushy-tailed woodrat cause problems in buildings by fouling stored materials and

food supplies.

Life history informationPreferred habitat-Woodrats may be found in forest habitats throughout their range.

Feeding habit-Primary foods are green foliage, fruits, and seeds. Food is stored

for winter use.

126

Trapping-In buildings, a particularly effective trap set for capturing woodrats is the

stovepipe set. Place a section of stovepipe 6 inches in diameter along a wall and set

a Conibear 110 or a no. 0 jump trap in it (see chapter 4). Bait the trap with nutmeats

or raisins. A board leaned against the wall to form a tunnel also may be used to

make a trap set. Seal all points of woodrat access to prevent re-entry into buildings.

In the field, woodrats are easily taken with wooden-base rat traps or live-traps placed

near nests or in active runways and baited with prunes, raisins, or nutmeats

Shooting--Shooting is usually ineffective as a control. It can be done on a limited

basis in areas where shooting does not pose a hazard, but it is generally only a

temporary measure.

Nest destruction--Nest destruction has been suggested as a control approach

during periods of inclement weather. In areas of dense brush cover or litter it is

unlikely, however, that the resulting exposure of the animals will be sufficent to cause

their death. No data are available on the effectiveness of this procedure (California

Forest Pest Council 1992).

Silvicultural modifications-Precommercial thinning and sanitation cutting of slash

and brush to reduce favorable habitat conditions and to improve growing conditions

for young conifer stands have proven effective in reducing and preventing woodrat

problems (California Forest Pest Council 1992).

ReferencesCalifornia Forest Pest Council. 1992. Forest pest conditions in California-1992.

Sacramento, CA: California Department of Forestry and Fire Protection. 43 p.

Clark, J.P. 1986. Wood rat. In: Vertebrate pest control handbook. Sacramento, CA:

State of California, Department of Food and Agriculture, Division of Plant Industry:

619-1 to 619-3.

Cranford, J.A. 1977. Home range and habitat utilization by Neotoma fuscipes as

determined by radiotelemetry. Journal of Mammalogy. 58(2): 165-172.

Hooven, E.F. 1959. Dusky-footed woodrat in young Douglas-fir. Res. Note 41.

Corvallis, OR: Forest Lands Research, Oregon Forest Research Center. 24 p.

Lindsdale, J.M.; Tevis, L.P., Jr. 1951. The dusky-footed woodrat. Berkeley, CA:

University of California. 664 p.

Marsh, R.E. 1962. Mole and woodrat control. In: Proceedings, National Pest Control

Association; 1962 February 6-7; Sacramento, CA. Elizabeth, NJ: National Pest

Control Association: 98-112.

Murray, K.F.; Barnes, A.M. 1969. Distribution and habitat of the woodrat, Neotoma

fuscipes, in northeastern California. Journal of Mammalogy. 50: 43-48.

Salmon, T.P. 1983. Woodrats. In: Timm, R.M., ed. Prevention and control of wildlife

damage. Lincoln, NE: University of Nebraska, Cooperative Extension Service:

B-121 to B-124.

Sullivan, T.P. 1992. Tree squirrels, woodrats, and beaver. In: Black, H.C., tech. ed.

Silvicultural approaches to animal damage management in Pacific Northwest forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 271-287. Chapter 13.

128
Porcupine

(Erethizon dorsatum)

Description-The most distinctive characteristic of

this large, yellowish-black rodent is the stiff quills,

especially on the rump and tail. The animals weigh

up to 33 pounds.

Economic significance-Clipping and basal barking

by porcupines on seedlings and saplings often kills the

trees. (Pocket gophers cause similar damage.) Barking

of the upper portions of older trees results in deformities

that reduce commercial value. Most of the feeding on

conifers occurs from late summer through winter.

Damage usually occurs in conifer stands between 5

and 30 years old. The most serious damage results

from complete removal of bark from the tree bole.

Occasionally, dogs, livestock, and wild animals are

blinded or unable to feed because of quill punctures after an encounter with a

porcupine. The injured animal may die.

Porcupines also cause nuisance damage around campgrounds and administrative

sites. Signs, harnesses, tool handles, automobile tires, privies, and other objects

often are damaged.

Life history informationPreferred habitat-Favored areas are conifer forests where there are rock outcrops

or old trees and logs suitable for dens.

Feedjng habits-Bark, buds, grasses, and forbs are taken seasonally. Bark feeding

usually does not start until late summer when herbaceous vegetation becomes mature

and dry. Feeding injuries to coniferous trees by porcupines are well documented in

the Northeastern, North-Central, and Western United States. Damage also is serious

in young Sitka spruce plantations in Alaska.

Porcupines prefer to feed on large-diameter stems, as well as the dominant and

codominant trees within a given stand. Any damage to a hemlock stem may affect

future timber production or quality and may increase the tree’s susceptibility to attack

by insects and diseases.

Activity-Porcupines actively forage from dusk through early morning. Animals often

remain in one area for many days, particularly during stormy weather.

Reproduction-A single young is born each year during May or June, after a gestation period of about 7 months. The minimum breeding age is 1 year, with most

females breeding each year.

Damage problems and their managementldentification--Porcupine use is characterized by prominent horizontal tooth marks,

1/8 inch wide, in the sapwood (fig. 34). On larger, heavily barked trees, pieces of the

outer bark, 1/2 to 1 inch, often are found at the base of trees. Clipped conifer

needles, quills, and oblong droppings 1 inch long also indicate porcupines.

129

Figure 35-Traps set in a porcupine scent station set.

Scent station sets can be inconspicuously located in areas of concentrated damage

(fig. 35). Any material with a fetid odor, such as rotted fish or meat, should be placed

in the center of the station. The station is designed to reduce the chances of

nontarget species being trapped, while attracting porcupines to enter the station.

Biological control--Fishers are natural enemies of porcupines and should be

protected where they occur.

individual free protection--Plastic-mesh tubing can be used for protection of young

seedlings (see chapter 4).

Porcupine-resistant signs-Porcupine-resistant signs, made with a special plywood,

have been in use at some National Forests for several years, Generally, they have

resulted in at least a 50-percent reduction in damage-where damage had been moderate. Damage continued to occur, however, in areas where damage previously was

severe. Information on the availability of these signs may be obtained from the Equipment Development Center, USDA Forest Service, Missoula, MT. Resistant signs have

been used in several regions of the Forest Service and have proven cost-effective.

The price of the special plywood was about $1 per square foot in 1988.

131
Fencing-Woven wire or electric fencing may be used to fence porcupines out of an

area, but high cost generally limits this method to small areas of high value. One of

the most practical uses of fencing is to use wire-mesh drift fences or metal flashing

as low as 24 inches to direct porcupines to traps set in openings at the ends of the

fence (Dodge and Borrecco 1992).

Silvicultural modifications-Habitat changes resulting from harvesting and other

silvicultural treatments may increase or decrease habitat suitability for porcupines,

although data are lacking on the effects of these practices on porcupine populations,

habitat use, and damage. Dodge and Borrecco (1992) note that several forest management practices, such as managing for greater species diversity, delaying thinning,

maintaining higher stand densitites, and removing natural and artificial sites (log

dumps, slash and other debris), have the potential for reducing porcupine problems.

ReferencesAnthony, R.M.; Evans, J.; Lindsey, G. 1986. Strychnine-salt blocks for controlling

porcupines in pine forests: efficacy and hazards. In: Salmon, T.P.; Marsh, R.E.;

Beadle, D.E., eds. Proceedings, 12th vertebrate pest conference; 1986 May 4-6;

San Diego, CA. Davis, CA: University of California: 191-195.

Borrecco, J.E.; Black, H.C. 1990. Animal damage problems and control activities on

National Forest System lands. In: Davis, L.R.; Marsh, R.E.; Beadle, D.E., eds.

Proceedings, 14th vertebrate pest conference; 1990 March 6-8; Sacramento, CA.

Davis, CA: University of California: 192-198.

Costello, D.F. 1966. World of the porcupine. Philadelphia, PA: Lippincott. 157 p.

Dodge, W.E. 1982. Porcupines. In: Chapman, J.; Feldhamer, C., eds. Wild mammals

of North America: biology, management, and economics. Baltimore, MD: Johns

Hopkins University Press: 355-366.

Dodge, W.E.; Barnes, V.G., Jr. 1975. Movements, home range, and control of

porcupines in western Oregon. Leafl. 507. Washington, DC: U.S. Department of

the Interior, Fish and Wildlife Service. 7 p.

Dodge, W. E.; Borrecco, J. E. 1992. Porcupines. In: Black, H.C. tech. ed.

Silvicultural approaches to animal damage management in Pacific Northwest forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 253-270. Chapter 12.

Dodge, W.E.; Canutt, P.R. 1969. A review of the status of the porcupine (Erethizon

dursatum) in western Oregon. Olympia, WA: U.S. Department of the Interior, Sport

Fisheries and Wildlife; Portland, OR: U.S. Department of Agriculture, Forest

Service. 25 p.

Evans, J. 1987. The porcupine in the Pacific Northwest. In: Baumgartner, D.M.;

Mahoney, R.L.; Evans, J. [and others], eds. Proceedings, symposium on animal

damage management in Pacific Northwest forests; 1987 March 25-27; Spokane,

WA. Pullman, WA: Washington State University: 75-78.

132
Mountain Beaver

(Aplodontia rufa)

Hooven, E.F. 1971. The porcupine in Oregon, its life history and control. Res. Pap.

10. Corvallis, OR: Oregon State University, School of Forestry, Forest Research

Laboratory. 22 p.

Lawrence, W.H. 1957. Porcupine control: a problem analysis. For. Res. Note 16.

Centralia, WA: Weyerhaeuser Timber Co., Forestry Research Center. 43 p.

Schemnitz, S.D. 1983. Porcupines. In: Timm, R.M., ed. Prevention and control of

wildlife damage. Lincoln, NE: University of Nebraska, Great Plains Agricultural

Council and Nebraska Cooperative Extension Service: B71-B74.

Sullivan, T.P.; Jackson, W.T.; Pojar, J.; Banner, A. 1986. Impact of feeding

damage by the porcupine on western hemlock-Sitka spruce forests of

north-coastal British Columbia. Canadian Journal of Forest Research. 16: 642-647.

U.S. Department of Agriculture, Forest Service. 1975. New porcupine-resistant

signs. Equip. Tips 7571 2306. Missoula, MT: U.S. Department of Agriculture,

Forest Service, Equipment Development Center. 1 p.

Yocum, C.F. 1971. Invasion of Humboldt and Del None Counties of northwestern

California by porcupines. Murrelet. 52(1): 1-6.

Description-Mountain beaver are about the

size of muskrats; head and body length is

about 14 inches. Adult mountain beaver weigh

about 2 pounds. They have small rounded

ears, small eyes, and short, stubby tails. Color

is blackish brown all over, except for a whitish

spot below the ear. There are five toes on

each foot, with the reduced thumb lacking a

claw. Size, color, and lack of a tail distinguish it

from other mammals within its range.

Economic significance-Mountain beavers

cause serious damage to Douglas-fir plantations during establishment, which may

continue through the sapling and pole stages of development. They rarely cause

damage to mature trees; however, lateral and terminal branches may be removed

from trees up to 10 feet tall. Basal barking and undermining of tree roots frequently

occur in young-growth stands. Root cutting also occurs. This damage often is not

detected until after precommercial thinning; in some instances, thinning may

stimulate damage. Plantations up to 4 years old and precommercially thinned stands

12 to 15 years old are particularly susceptible to damage. Burrowing activities of

mountain beavers occasionally undermine road beds, irrigation ditches, and earthen

dams.

Life history informationPreferred habitat--Distribution is limited mainly to western Oregon and Washington,

although the range of the species extends from southern British Columbia to central

California. Mountain beavers are found in suitable forested habits throughout their

range; mountain beaver populations thrive on suitable sites in cutover areas. Populations are most abundant near streams and on areas with deep moist soils.

133
Feeding habits--Mountain beavers are herbivorous and eat a wide variety of herbaceous and woody plants. Sword-fern and “bracken fern” comprise an important part

of their diet throughout the year. Feeding is primarily at night, with foraging occurring

within a few feet of a tunnel exit.

Activity--Most surface activity takes place at night, but movements within the extensive burrow system may occur either night or day. Although mountain beavers do not

hibernate, their activities in many areas are restricted in the winter. Some burrowing

may occur in the snow. Late spring is the season of greatest burrowing activity. The

burrow system consists of extensive irregular tunnels, 6 to 8 inches in diameter.

These tunnels form a network of passages from a few inches to several feet beneath

the ground surface. There are many entrances and unrepaired roof openings. A typical burrow system occupies about 0.3 acre (range, 0.1 to 0.5 acre). Burrow systems

may overlap. Each system is occupied by a single mountain beaver, except during

the spring and summer when juveniles occupy a system with an adult female before

dispersing. The nest is large (up to 2 feet in diameter) and a fairly elaborate structure

containing numerous layers of packed leaves and other foliage. It usually is located

under logs or stumps at a depth of 3 to 5 feet.

Reproduction--Breeding takes place once a year in late February or early March.

From two to four young are born after a gestation period of 28 to 30 days. Females

do not bear young until they are in their second year.

Damage problems and their managementIdentification--The presence of active mountain beaver burrow systems generally is

evident. Clipping by mountain beaver leaves an oblique cut characteristic of rodents

and lagomorphs, but it usually can be distinguished from clipping by other animals because of the multiple cuts, which leave a serrated cut end. On larger seedlings, the

laterals are frequently clipped off, leaving 1- to 3-inch stubs (fig. 36). Basal girdling

may occur on saplings and small pole-size trees. Superficially, the basal girdling may

look like bear damage; however, mountain beavers do not leave any discarded bark

at the base of the tree. Mountain beavers leave scattered horizontal and diagonal

tooth marks, whereas black bears leave deep, vertical incisor marks when scraping

the sapwood.

Determining the need for damage management-Wherever an active burrow system exists, the potential for clipping of young seedlings exists. When the population

of mountain beavers exceeds two per acre, a high rate of clipping can be expected,

unless some method of damage control is undertaken. If planting is planned in the

immediate vicinity of active mountain beaver burrow systems, some method of damage prevention will be needed.

Management methodsBaiting--No Federally registered rodenticides are available to control mountain beavers. A Special Local Needs (24-C) registration for pelleted strychnine bait may be in

effect in some areas.

134

Table 3-Estimated effectiveness of 3 control

methods on an area with a moderate to high

population (3 to 5 active burrow systems per

acre) of mountain beaver

Control treatment

Expected terminal clipping

1 year after planting

None

30-inch tubes

18-inch tubes

16-inch tubes

10-inch tubes

Broadcast burn

Trap

Trap and

broadcast burn

50-80

l-4

2-5

10-15

20-30

20-30

10-25

4-8

Most animals (up to 90 percent) are caught in the first 1 or 2 days. Leaving the traps

set for 4 to 5 days before removing them increases the chance of catching those

animals that may have avoided traps or that do not encounter traps during the first

part of the trapping period. During spring and summer trapping, juveniles are likely to

occupy the burrow systems with adults. This necessitates an additional trap check,

after the first day, to remove animals caught and to reset traps to catch mountain

beavers remaining in burrow systems having multiple occupants.

During September and October, active mountain beaver sign may not be readily apparent. The lack of active sign can result in reduced trapping efficiency during this

period. Scheduling of trapping operations should be delayed for at least 3 to 4 weeks

after burning an area to allow development of new sign. If trapping is attempted immediately after burning, many-active mountain beaver burrow systems may be

overlooked.

Trapping should be completed before planting, preferably as close to planting time as

possible and no sooner than 6 months before planting. Where adjacent populations

exist, a 300-foot-wide buffer strip may be trapped in occupied habitat to reduce

reinvasion; however, this is of questionable operational value.

Individual tree protection--Plastic-mesh tubing should be considered as an

alternative to trapping in areas of less than 5 acres. Use plastic tubing, 18 to 24

inches high, anchored with a single wire pin or wooden stake. For additional details

see Campbell and Evans (1975; also reprinted in appendix 3).

136
-

Woodchuck

(Marmota monax)

Feldhamer, G.A.; Rochelle, J.A. 1982. Mountain beaver (Aplodontia rufa). In:

Chapman, J.A.; Feldhamer, G.A., eds. Wild mammals of North America: biology,

management, and economics. Baltimore, MD: Johns Hopkins University Press:

167-175.

Godin, A.J. 1964. A review of the literature on the mountain beaver. Spec. Sci. Rep.,

Wildl. 78. Washington, DC: U.S. Department of the Interior, Bureau of Sport

Fisheries and Wildlife. 52 p.

Hooven, E.F. 1977. The mountain beaver in Oregon: its life history and control. Res.

Pap. 30. Corvallis, OR: Oregon State University, Forest Research Laboratory. 20 p.

Johnson, S.R. 1971. The thermal regulation, micro-climate, and distribution of the

mountain beaver, Aplodontia rufa pacifica Merriam. Corvallis, OR: Oregon State

University. 164 p. Ph.D. dissertation.

Lovejoy, B.P. 1972. A capture-recapture analysis of a mountain beaver population in

western Oregon. Corvallis, OR: Oregon State University. 105 p. Ph.D. dissertation.

Martin, P. 1971. Movements and activities of the mountain beaver (Aplodontia rufa).

Journal of Mammalogy. 52(4): 717-723.

Motobu, D.; Jones, M. 1977. Trapping guidelines for mountain beaver. Tech. Rep.

042-4101/77/20. Centralia, WA: Weyerhaeuser Western Forestry Research Center.

28 p.

Motubu, D.T.; Jones, M. 1978. Effects of controlled slash burning on the mountain

beaver (Aplodontia rufa). Northwest Science. 52(2): 92-99.

Mountain Beaver Subcommittee, Northwest Forest-Animal Damage Committee.

1979. Survey of mountain beaver damage to forests in the Pacific Northwest,

1977. DNR Note 26. Olympia, WA: Department of Natural Resources. 16 p.

Neal, F.D.; Borrecco, J.E. 1981. Distribution and relationship of mountain beaver to

openings in sapling stands. Northwest Science. 55(2): 79-86.

Scheffer, T.H. 1929. Mountain beavers in the Pacific Northwest: their habits,

economic status, and control. Farmers’ Bull. 1598. Washington, DC: U.S.

Department of Agriculture. 18 p.

Smutthwaite, D. 1986. Mountain beaver-the rodent that gets no respect. American

Forests. 92(5): 45-50.

Voth, E.H. 1968. Food habits of the Pacific mountain beaver, Aplodontia rufa pacifica

Merriam. Corvallis, OR: Oregon State University. 263 p. Ph.D. dissertation.

Description--Also known as ground hogs or whistle pigs, woodchucks occupy the

Eastern United States from Canada to northern Alabama. They dig extensive ground

burrows on farmlands and may be abundant in wooded areas adjoining open lands;

excavated mounds of earth are at the main burrow entrances. The openings of the

main burrows are about 10 inches in diameter. Woodchucks usually are brownish

gray, and weigh 5 to 10 pounds.

139
Economic significance-Although woodchucks seldom cause extensive damage to

trees, they frequently destroy young trees near their burrows. If trees are planted in

woodlot openings or shelterwoods where woodchucks have established their burrow

systems, the planted trees may be extensively damaged or destroyed, even though

natural regeneration remains undamaged.

Life history informationPreferred habitat-Woodchucks occupy open farmlands, hedgerows, brushy

“islands,” edges of woodlands, and woodland openings.

Feeding habits-Although legumes and grasses are preferred foods, a wide variety

of plants is eaten.

Activity--Feeding and other aboveground activities are most common at dawn and

dusk. Woodchucks hibernate during colder months, usually from about October to

March, depending on latitude. New burrows usually are constructed during late

summer.

Reproduction-Breeding occurs once a year, shortly after emergence from hibernation. Two to six young are born about 32 days later. They are weaned and soon

thereafter leave the home burrow, in June or July.

Damage problems and their managementIdentification-Young trees may be clipped off or eaten. Older trees may be chewed

or clawed extensively near ground level, particularly in spring or early summer. Damaged trees usually are near burrow entrances.

Status as game animals--Woodchucks are game animals in most states. Thus, it is

important to check with the state wildlife agency, APHIS-ADC, or the Cooperative

Extension Service for control recommendations.

Management methodsFumigants-Burrow fumigation cartridges may be available at farm supply stores and

are sold by the Pocatello Supply Depot, USDA APHIS-ADC, 238 E. Dillon, Pocatello,

ID 83201. Because they are ignited in use, the cartridges are a fire hazard-do not

use them under buildings or when fire danger is high. The cartridges burn slowly to

produce carbon monoxide and will not explode if properly used. Directions for use

are on the label and must be followed precisely. Fumigation of burrows before the

young emerge is especially effective, as is treatment of a large area at one time.

Where fire hazard exists, trapping with no. 2 steel traps or live-traps may be effective:

check with your state wildlife officials to determine legality and restrictions. If equipped with telescopic sights, rifles may be effective in some areas, where legal and

safe.

In recreation areas and other locations where individual high-value trees need protection, hardware-cloth tree guards may be helpful.

140
ReferencesBollinger, R., Jr. 1983. Woodchucks. In: Timm, R.E., ed. Prevention and control of

wildlife damage. Lincoln, NE: University of Nebraska, Cooperative Extension

Service: B-153 to B-156.

Caslick, J.W.; Decker, D.J. 1981. Controlling wildlife damage in homes and

gardens. Info. Bull. 176. Ithaca, NY: New York State College of Agriculture and

Life Sciences, Cornell University. 28 p.

Snowshoe Hare

(Lepus americanus)

Description-Also known as the varying hare, most

subspecies of this large-footed hare turn white during

winter and dark brown in summer. The main

distinguishing feature of the snowshoe hare is its

coloring. Its ears are relatively short (3-1/2 to 4

inches) for a hare. Head and body length is between

13 to 18 inches.

Economic significance-Snowshoe hares provide a

limited amount of sport hunting in parts of their

range. The importance of this sport may increase in

the future, as hunting pressure increases and habitat

for other game species becomes limited.

Hares are food for large predators and, in this way, act as an important buffer

species for other game animals.

In localized areas, hare damage to conifer plantations is more critical than that

caused by big game. Clipping by hares or rabbits often results in loss of seedlings,

especially small containerized stock, but suppression of growth generally occurs

when seedlings are exposed to light to moderate injury.

Life history informationPreferred habitats-Throughout their range, snowshoe hares occupy most commercial forest lands if there is an abundance of good protective cover provided by

low-growing vegetation and dense brush.

Feeding habits-Hares prefer a woody diet of foliage, stems, and bark of shrubs

and trees throughout most of the year, although herbaceous vegetation is their main

food in summer.

Activity--Daily movements usually are limited to a small area. The period of greatest

activity is from dusk to dawn. Snowshoe hares do not migrate, but they may shift

their feeding activities to different vegetative types when deep-snow conditions exist

in winter.

Reproduction-Snowshoe hares normally have three or four young per litter and

may have up to four litters a year. Young are born from April through August. The

gestation period is from 36 to 40 days. Newborn young are well developed and are

soon able to move about.

141

Silvicultural practice--Disposal of fuel, brush, and accumulations of logging debris

reduces the attractiveness of habitat for hares. When a serious hare-damage problem

is anticipated, use large-diameter seedlings with a caliper width of 0.2-0.3 inches. Do

not use containerized seedlings without plastic protectors.

Herbicides have been used to reduce herbaceous hiding cover to a low level, which

tends to discourage occupancy of the area by snowshoe hares. Borrecco (1976)

found a significant reduction in hare numbers and clipping (of conifer seedlings) on

plantations where vegetation was controlled.

ReferencesAdams, L. 1959. An analysis of a population of snowshoe hares in northwestern

Montana. Ecological Monographs. 29: 141-169.

Bider, J.R. 1961. An ecological study of the hare Lepus americanus. Canadian

Journal of Zoology. 39: 81-103.

Borrecco, J.E. 1976. Controlling damage by forest rodents and lagomorphs through

habitat manipulation. In: Siebe, C.C., ed. Proceedings, 7th vertebrate pest conference; 1976 March 9-11; Monterey, CA. Davis, CA: University of California:

203-210.

Broadhooks, H. E. 1965. Ecology and distribution of the pikas of Washington and

Alaska. American Midland Naturalist. 73: 299-335.

Campbell, D.L.; Evans, J. 1975. “Vexar” seedling protectors to reduce wildlife damage to Douglas-fir. Wildl. Leafl. 508. Olympia, WA: U.S. Department of the Interior,

Fish and Wildlife Service. 11 p.

Dolbeer, R.A. 1972. The snowshoe hare in the Western United States: its status and

potential as a game animal. In: Proceedings, 52d annual conference of the

Western Association of State Game and Fish Commissioners; [dates of meeting

unknown]; Portland, OR. [Location of publisher unknown]: [publisher unknown]:

437-451.

Giusti, G.A.; Schmidt, R.H.; Timm, R.M. [and others]. 1992. In: Black, H.C., tech.

ed. Silvicultural approaches to animal damage management in Pacific Northwest

forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 289-307. Chapter 14.

Hartwell, H.D. 1969. Control of damage by snowshoe hares on forest plantations. In:

Black, H.C., ed. Proceedings, symposium on wildlife and reforestation in the

Pacific Northwest; 1968 September 12-13; Corvallis, OR. Corvallis, OR: Oregon

State University, School of Forestry: 80-81.

Hartwell, H.D.; Johnson, L.E. 1983. Survival and height of large and small Douglasfir seedlings in relation to animal damage six years after planting. DNR Note 38.

Olympia, WA: Washington Department of Natural Resources. 20 p.

McKillop, I.G.; Pepper, H.W.; Wilson, C.J. 1988. Improved specifications for rabbit

fencing for tree protection. Forestry. 1(4): 359-368.

Radvanyi, A. 1987. Snowshoe hares and forest plantations: a literature review and

problem analysis. Info. Rep. NOR-X-290. [Location of publisher unknown]:

Canadian Forestry Service, Northern Forestry Centre. 17 p.

143
Sullivan, T.P.; Sullivan, D.S. 1982a. Barking damage by snowshoe hares and red

squirrels in lodgepole pine stands in central British Columbia. Canadian Journal of

Forest Research. 12(2): 443-448.

Sullivan, T.P.; Sullivan, D.S. 1982b. Influence of fertilization on feeding attacks to

lodgepole pine by snowshoe hares and red squirrels. Forest Chronicle. 58:

263-266.

Sullivan, T.P.; Sullivan, D.S. 1986. Impact of feeding damage by snowshoe hares

on growth rates of juvenile lodgepole pine in central British Columbia. Canadian

Journal of Forest Research. 16(5): 1145-1149.

Sullivan, T.P.; Sullivan, D.S. 1988. Influence of stand thinning on snowshoe hare

population dynamics and feeding damage in a lodgepole pine forest. Journal of

Applied Ecology. 25: 791-805.

Black-Tailed Jackrabbit

(Lepus californicus)

Description-The black-tailed jackrabbit may be found

throughout the grasslands and open areas of the West.

It also occurs in less abundance on forest land, especially in clearcuttings and partial cuttings. It is grayish

dorsally, and nearly white beneath. Its conspicuous,

large (6 to 7 inches), black-tipped ears and black streak

on top of the tail distinguish it from all other hares.

Economic significance-The black-tailed jackrabbit

occasionally clips Douglas-fir and other conifer seedlings in plantations adjacent to grasslands or shrub

communities.

Life history informationPreferred habitat--Grassland and sagebrush areas are the preferred habitat of the

black-tailed jackrabbit.

Feeding habits--Forbs and grasses are dominant in the diet during spring and

summer. During fall and winter, shrubs are dominant in the diet.

Damage problems and their managementIdentification--On shrubs and tree seedlings, obliquely cut stems and branches

help identify clipping by black-tailed jackrabbits. The sighting of jackrabbits and

occurrence of round fecal pellets are indications that black-tailed jackrabbits are

in the area. On rangelands, forage cages can be used to determine forage use.

Determining the need for damage management-Damage is localized and has

been reported only sporadically. A study in Utah estimated that 5.8 jackrabbits consumed as much forage as one sheep on winter sheep range (Currie and Goodwin

1966). During periods of high population levels, several hundred jackrabbits may

occupy an area of 1 square mile.

Management methodsRepellents--Thiram is registered for use as a rabbit repellent. Repeated applications

may be needed each year to ensure adequate protection (see chapter 4).

144
Individual free protection-Plastic-mesh tubing can be used to effectively prevent

clipping. Tubes (30 inches high) should be placed over the seedlings when planting

or replanting areas exposed to damage (see chapter 4). For additional details see

Campbell and Evans (1975; also reprinted in appendix 3).

Fencing and other practices-Fencing, although expensive, may provide long-term

protection to areas of high value such as progeny test sites. Fences should be constructed of mesh or net wire with a weave of 2 inches across or less. A fence of

4 feet in height should exclude all rabbits and hares, except in areas with deep snow.

Fences must be secured to the ground to prevent rabbits and hares from digging

under them and most importantly, must be maintained (Giusti and others 1992).

Installing raptor perches at nurseries and seed orchards is a common practice,

although data are lacking on the effectivess of this procedure to control rabbits and

hares (and pocket gophers).

Baiting-Special local registrations may exist for use of anticoagulant baits to limit

damage by black-tailed jackrabbits.

Shooting and jackrabbit drives-Both drives and shooting may be used to reduce

hare numbers, but they require a great deal of personnel time, and shooting may

require special equipment such as night scopes or spotlights. State wildlife officials

should be consulted regarding restrictions, laws, and permits that may be required.

Silvicultural practices-Use of seedlings over 24 inches in height may reduce

clipping.

References-Also see the section on snowshoe hares for additional references on

hares and rabbits.

Crouch, G.L. 1969. Jackrabbits injure ponderosa pine seedlings. Tree Planters

Notes. 24(3): 15-17.

Currie, P.O.; Goodwin, D.L. 1966. Consumption of forage by blacktail jackrabbits on

salt-desert ranges in Utah. Journal of Mammalogy. 30(2): 304-311.

Dunn, J.P.; Chapman, J.A.; Marsh, R.E. 1982. Jackrabbits. In: Chapman, J.A.;

Feldhamer, G.A., eds. 1982. Wild mammals of North America: biology, management, and economics. Baltimore, MD: The Johns Hopkins University Press:

124-145.

Evans, J.; Hegdal, P.L.; Griffith, R.E., Jr. 1982. Wire fencing for controlling

jackrabbit damage. Bull. 618. [Location of publisher unknown]: University of Idaho,

Cooperative Extension Service. 7 p.

Giusti, G.A.; Schmidt, R.H.; Timm, R.M. [and others]. 1992. In: Black, H.C., tech.

ed. Silvicultural approaches to animal damage management in Pacific Northwest

forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Research Station: 289-307.

Chapter 14.

Knight, J.E. 1983. Jackrabbits. In: Timm, R.M., ed. Prevention and control of wildlife

damage. Lincoln, NE: University of Nebraska, Great Plains Agricultural Council and

Cooperative Extension Service: D-75 to D-80.

145
Nuttall’s (Mountain)

Cottontail

( Sylvilagus nuttah)

Description-This small grayish rabbit has short ears. It rarely uses burrows; instead

it makes runways through thick grass or other vegetation. It can be distinguished from

the desert cottontail and the black-tailed jackrabbit by its smaller size. Length of the

Nuttall’s cottontail is about 14 inches compared with 11 inches for the desert cottontail

and 22 inches for the black-tailed jackrabbit.

Economic significance-Nuttall’s cottontail is of minor importance in providing

hunting opportunities on National Forest lands. The dense habitat it occupies makes

both hunting and viewing difficult.

Life history informationPreferred habitat-Dense brush interspersed with openings provides ideal habitat.

Distribution extends throughout western Oregon and California, to areas east of the

Continental Divide, Montana, Wyoming, and Colorado.

Feeding habits-Buds, twigs, bark, grasses, and a wide variety of succulent forbs

are eaten.

Activity--The main period of activity is from dusk to dawn. Movements are confined

to very small areas.

Reproduction--NuttalI’s cottontails normally have from two to four litters per year,

with three to six young per litter. The young are born hairless and blind and spend

more time in the nest than hares do.

Damage problems and their managementldentification-Nuttall’s cottontails clip seedlings and small limbs up to 1/4 inch in

diameter, leaving an obliquely cut stem. (The appearance of clippings is similar to

those made by snowshoe hares, as shown earlier in fig. 1.) Their fecal pellets are

round and about 3/8 inch in diameter.

Determining the need for damage managemement-Damage is localized, with past

experience being the best indicator of potential problems.

Management methodsSilvicultural practices-Disposal of slash, brush, and accumulations of logging

debris reduces the attractiveness of habitat for rabbits. Use of herbicides and other

vegetation management practices to reduce food and cover also may alleviate rabbit

damage to conifer seedlings. When a serious rabbit damage problem is anticipated,

the use of seedlings 2 or more feet high will reduce damage.

Repellents (thiram)-In areas exposed to damage by rabbits, plant trees treated

with thiram. Repeated applications of thiram in the field may be required after each

growing season, until trees grow large enough to be out of danger. The repellent can

be applied effectively with a backpack sprayer. The recommended dilution is 1 gallon

of 20-percent thiram to 1 gallon of water (see chapter 4).

Individual free protection-Plastic-mesh tubing also may be used to protect individual tree seedlings. The tubes can be placed on newly planted or established seedlings and will provide protection of new and old foliage from clipping by rabbits. For

additional details see Campbell and Evans (1975; also reprinted in appendix 3).

Baits-No poisonous baits are registered to control the Nuttall’s cottontail.

146
References-Also see the section on snowshoe hares for additional references on

hares and rabbits.

Chapman, J.A.; Hockman, J.G.; Edwards, W.R. 1982. Cottontails. In: Chapman,

J.A.; Feldhammer, G.A., eds. 1982. Wild mammals of North America: biology,

management, and economics. Baltimore, MD: The Johns Hopkins University

Press: 83-123.

Giusti, G.A.; Schmidt, R.H.; Timm, R.M. [and others]. 1992. In: Black, H.C., tech.

ed. Silvicultural approaches to animal damage management in Pacific Northwest

forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Research Station: 289-307.

Chapter 14.

McKay, D.O. 1975. Dynamics of a population of mountain cottontail rabbits in central

Oregon. Corvallis, OR: Oregon State University. 63 p. M.S. thesis.

Orr, R.T. 1940. The rabbits of California. Oct. Pap. 19. [Location of publisher

unknown]: California Academy of Sciences. 227 p.

Brush Rabbit

(Sylvilagus bachmani)

Description-The small brown brush rabbit

has short ears and tail. It rarely uses burrows;

instead, it makes runways through thick grass

or other vegetation. It can be distinguished

from the desert cottontail and black-tailed

jackrabbit by its smaller size. Length of the

brush rabbit is about 13 inches compared

with about 15 inches for the desert cottontail

and about 22 inches for the black-tailed

jackrabbit.

Economic significance-The brush rabbit is

of minor importance in providing hunting opportunities on National Forest lands. The

denseness of the habitat that it occupies makes both hunting and viewing difficult.

Life history informationPreferred habitat-Dense brush interspersed with openings provides ideal habitat.

Feeding habits--Buds, twigs, bark, grasses, and a wide variety of succulent forbs

are eaten.

Acfivity--The main period of activity is from dusk to dawn. Movements are confined

to very small areas.

Reproduction--Brush rabbits normally have from three to four litters per year, with

from three to six young per litter. The young are born hairless and blind.

Damage problems and their managementIdentification--Brush rabbits clip seedlings and small limbs up to 1/4 inch in diameter

and leave an obliquely cut stem. (The appearance of clippings is similar to those

made by other rabbits and hares.) Their fecal pellets (droppings) are round and about

3/8 inch in diameter.

Determining the need for damage management-Damage is localized; past

history is the best indicator of potential problems.

147
Birds

148

Management methodsSilvicultural practices--Disposing of slash, brush, and accumulations of logging debris reduces the attractiveness of the habitat for rabbits. Use of herbicides and other

vegetation management practices to reduce food and cover also may alleviate rabbit

damage to conifer seedlings. When a serious rabbit damage problem is anticipated,

use of seedlings 2 or more feet high will reduce feeding damage.

Repellents--ln areas exposed to damage by rabbits, plant trees treated with thiram.

Repeated applications of thiram in the field may be required after each growing season until trees grow large enough to be out of danger. The repellent can be applied

effectively with a backpack sprayer. The recommended dilution is 1 gallon of 20 percent thiram to 1 gallon of water.

Individual free protection-Plastic-mesh tubing also may be used to protect individual tree seedlings. The tubes can be placed on newly planted or established seedlings and will provide protection of new and old foliage from clipping by rabbits. For

additional details see Campbell and Evans (1975; also reprinted in appendix 3).

Baiting-No poisonous baits are registered to control brush rabbits.

References-Also see the section on snowshoe hares for additional references on

hares and rabbits.

Connell, J.H. 1954. Home range and mobility of brush rabbits in California chaparral.

Journal of Mammalogy. 35(3): 392-405.

Hooven, E.F. 1966. A test of thiram on two rabbit-infested areas in Oregon. Tree

Planters’ Notes. 79: 1-3.

Mossman, A.S. 1955. Reproduction of the brush rabbit in California. Journal of Wildlife Management. 19(2): 177-184.

Orr, R.T. 1940. The rabbits of California. Oct. Pap. 19. [Location of publisher

unknown]: California Academy of Sciences. 227 p.

Shields, P.W. 1960. Movement patterns of brush rabbits in northwestern California.

Journal of Wildlife Management. 24(4): 381-386.

The consumption of conifer seeds by birds is a factor in reducing the efficacy of direct

seeding (and regeneration by natural seedfall) or preventing its use for forest regeneration and bare-root nursery programs. During the 1950s and 1960s between onethird and one-half of the artificial reforestation in the Pacific Northwest was accomplished by direct seeding using seed treated with toxicants or repellents for rodent

and bird management. In the 1970s direct-seeding was largely discontinued.

Birds also may damage terminal shoots by perching and may browse buds and

needles.

Conifer tree buds are destroyed by many species of birds. Mature seeds are eaten by

mourning dove, juncos, eastern meadowlark, robin, Clark’s nutcracker, jays, crossbills,

pine siskins, finches, woodpeckers, and nuthatches. Germinating seedlings are clipped by many species, especially if the seed coat is attached.

Drilling by sapsuckers may inflict injuries serious enough to result in log-quality

degrade.
Birds may foul stored equipment, and their nests may constitute an electrical fire

hazard around buildings.

ReferencesBock, C.E.; Lepthien, L.W. 1976. Synchronous eruptions of boreal seed-eating birds.

American Naturalist. 110: 559-571.

Eastman, W.R., Jr. 1960. Eating of tree seeds by birds in central Oregon. Res.

Note 42. Corvallis, OR: Oregon Forest Research Center. 24 p.

Gashwiler, J.S. 1967. Conifer seed survival in a western Oregon clearcut. Ecology.

48: 431-438.

Gashwiler, J.S. 1970. Further study of conifer seed survival in a western Oregon

clearcut. Ecology. 51: 849-854.

Hagar, D.C. 1960. The interrelationships of logging, birds, and timber regeneration in

the Douglas-fir region of northwestern California. Ecology. 41: 116-125.

Noble, D.L.; Shepperd, W.D. 1973. Gray-headed juncos important in first season

mortality of Engelmann spruce. Journal of Forestry. 71: 763-765.

Pank, L.F. 1974. A bibliography on seed-eating mammals and birds that affect forest

regeneration. Res. Rep. 13. Washington, DC: U.S. Department of the Interior, Fish

and Wildlife Service. 29 p.

Shearer, R.C. 1987. Rodent and bird impacts on direct seeding and natural regeneration in the northern Rockies. In: Baumgartner, D.M.; Mahoney, R.L.; Evans, J.

[and others], eds. Proceedings, symposium on animal damage management in the

Pacific Northwest; 1987 March 25-27; Spokane, WA. Pullman, WA: Washington

State University, Cooperative Extension: 65.

Smith, C.; Balda, R. 1979. Competition among insects, birds, and mammals for conifer seed. American Zoologist. [Vol. unknown]: 1065-1083.

Smith, C.F.; Aldous, S.E. 1947. The influence of mammals and birds in retarding

artificial and natural seeding of coniferous forests in the United States. Journal of

Forestry. 69: 361-369.

West, S.D. 1992. Seed-eating mammals and birds. In: Black, H.C., tech. ed. Silvicultural approaches to animal damage management in Pacific Northwest forests.

Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S. Department of Agriculture,

Forest Service, Pacific Northwest Research Station: 167-186. Chapter 8.

149
Blue Grouse

(Dendragapus obscurus)

Description-Grouse are ground-dwelling,

chickenlike birds. The blue grouse is dusky gray

or blackish in color, with a light band at the tip of

a black tail. Males have a yellowish-orange comb

above the eyes. Females are grayish brown and

barred with black, with a blackish tail. Coloration

distinguishes the blue grouse from the ruffed

grouse and the spruce grouse.

Economic significance-Blue grouse occur

commonly from British Columbia to northern

California. Although bud removal and clipping of needles occur sporadically, they are

far more extensive than was realized in the past-bud clipping often has been

overlooked or more often misidentified as deer browsing. Blue grouse usually remove

only a few buds from each seedling, but the impact of bud clipping on small

Douglas-fir seedlings may suppress height growth significantly (Black and others

1979).

Life History InformationPreferred habitat-Blue grouse inhabit coniferous forests, particularly in the winter.

This grouse nests and raises its young in nonforested areas, in native grasslands, or

the early seral stages of a forest after logging or fire.

Feeding habits--Young grouse feed primarily on grasshoppers and other insects. In

fall, berries, seeds, and succulent plant parts are eaten. During winter and early

spring, the diet consists primarily of conifer buds and needles and occasionally of

mistletoe.

Acfivity--Blue grouse are conspicuous in late spring when the males are “hooting”

during the spring courtship period. During summer and fall, the females and broods

are noticeable at mid and low elevations on mountain and ridge slopes. In winter and

early spring, blue grouse usually are found concealed in heavy coniferous cover at

high elevations; during this period they seldom feed on the ground.

Reproduction-Five to ten young are hatched per brooding female. The chicks stay

with the hen through fall.

Damage problems and their managementIdentification-Buds are neatly plucked from the stem, leaving only the inconspicuous point of attachment. Needle clipping may result in the removal of the entire

needle or only a portion of it. The combination of irregular needle clipping and clean

removal of buds identifies the typical feeding of blue grouse (fig. 40).

Determining the need for damage management-Light damage to conifer seedlings can be tolerated without significant growth suppression. In localized areas with

large grouse populations and with evidence of heavy damage on adjacent plantations,

plastic-mesh tubing may be used to protect individual tree seedlings. This practice

has not been thoroughly evaluated, however.

150


Common and Scientific Names

Appendix 1:

153
Plant and Tree

Species

Ponderosa pine

Sitka spruce

Western hemlock

Grand fir

Douglas-fir

True firs

Willows

Aspen/Cottonwoods

California black oak

Tanoak

Pacific madrone

Cypress

Redstem ceanothus

Fireweed

Pinegrass

Geranium

Cheatgrass

Tarweed

Lupine

Dandelion

Alfalfa

Douglas lotus

Dutch white clover

Alsike (clover)

Yellow sweet clover

Subclover

Red clover

Burnet

Perrenial rye (grass)

Orchard-grass

Oatgrass

Bitterbrush

Sword-fern

Pinus ponderosa Dougl. ex Laws.

Picea sifchensis (Bong.) Carr.

Tsuga heterophylla (Raf.) Sarg.

Abies grandis (Dougl. ex D. Don) Lindl.

Pseudotsuga menziesii (Mirb.) Franco

Abies spp.

Salix spp.

Populus spp.

Quercus kelloggii Newb.

Lithocarpus densiflorus (Hook. & Arn.) Rehd.

Arbutus menziesii Pursh

Cupressus sp.

Ceanothus sanguineus Pursh

Epilobium spp.

Calamagrostis rubescens Buckl.

Geranium spp.

Bromus tectorum L.

Madia spp.

Lupinus spp.

Taraxacum officinale Weber

Medicago sativa L.

Lotus nevadensis var. douglasii

(Green) Ottley (L.d.)

Trifolium repens L.

Trifolium hybridum L.

Melilotus officinalis (L.) Lam.

Trifolium incarnatum L.

Trifolium pra tense L.

Sanguisorba spp.

Lolium perenne L.

Dactylis glomerata L.

Danthonia spp.

Purshia tridentata (Pursh) DC.

Polystichum munitum (Kaulf.) Presl

154
Animal Species

Bracken

Mistletoe

Mountain beaver

Deer mouse

California redbacked vole

Meadow vole

White-tailed deer

Snowshoe hare

Beaver (American)

Porcupine

Black-tailed jackrabbit

Cottontail (rabbit)

Red squirrel

Western gray squirrel

Dusky-footed woodrat

Unita ground squirrel

Bobcat

Coyote

Black-footed ferret

Black-tailed prairie dog

Belding ground squirrel

Columbian ground squirrel

Black-tailed deer

Rocky Mountain elk

Roosevelt elk

Mule deer

Chickaree (Douglas squirrel)

Badger

Bushy-tailed woodrat

Black bear

Norway rat

Golden-mantled ground squirrel

Brush rabbit

Nutria

Pteridium aquilinum (L.) Kuhn.

Arceuthobium spp.

Aplodontia rufa

Peromyscus maniculatus

Clethrionomys occidentalis

Microtus pennsylvanicus

Odocoileus virginianus leucurus

Lepus americanus

Castor canadensis

Erethizon dorsatum

Lepus californicus

Sylvilagus floridanus

Tamiasciurus hudsonicus

Sciurus griseus

Neotoma fuscipes

Spermophilus richardsoni

Lynx rufus

Canis latrans

Mustela nigripes

Cynomys ludovicianus

Spermophilus beldingi

Spermophilus columbianus

Odocoileus hemionus columbianus

Cervus elaphus nelsoni

Cervus elaphus roosevelti

Odocoileus hemionus

Tamiasciurus douglasi

Taxidea taxus

Neotoma cinerea

Ursus americanus

Rattus norvegicus

Spermophilus lateralis

Sylvilagus bachmani

Myocaster coypus

155
Birds

Insects

156

Pine mouse

House mouse

Woodchuck

Nuttall’s (mountain) cottontail

Pocket gophers

Shrews

Moles

Chipmunks

Weasels

Barn owl

Great horned owl

Hawks

Sparrow

Starling

Grouse

Grosbeak

Pheasant

Quail

Swallow

Mourning dove

Junco

Southern meadowlark

Robin

Clark’s nutcracker

Jays

Crossbills

Siskin (pine siskin)

Finches

Woodpeckers

Nuthatches

Sapsuckers

Blue grouse

Ants

Grasshoppers

Microtus pinetorum

Mus musculus

Marmota monax

Sylvilagus nuttalli

Thomomys spp. (and other genera)

Sorex spp.

Scapanus spp.

Eutamias spp.

Mustela spp.

Tyto alba

Bubo viginianus

Buteo spp.

Zonotrichia spp. (and other genera)

Sturnus vulgaris

Dendragapus sp.

Pheucficus sp. (and other genera)

Phasianus colchicus

Oreortyx sp. (and other genera)

Tachycineta sp. (and other genera)

Zenaida macroura

Junco spp.

Sturnella sp.

Turdus migratorius

Nucifraga columbiana

Cyanocitta sp. (and other genera)

Loxia spp.

Carduelis pinus

Carpodacus spp.

Dryocopus spp. (and other genera)

Sitta spp.

Sphyrapicus spp.

Dendragapus obscurus

Formicidae

Acrindidae
Memorandum of Understanding

Appendix 2:

157
APHIS# 12-34-71-0017MU

FS# 93-SMU-118

MASTER MEMORANDUM OF UNDERSTANDING

between the

ANIMAL AND PLANT HEALTH INSPECTION SERVICE

and the

FOREST SERVICE

UNITED STATES DEPARTMENT OF AGRICULTURE

I. PURPOSE

The Animal and Plant Health Inspection Service (APHIS-ADC) and the Forest

Service (FS) are agencies of the United States Department of Agriculture (USDA)

concerned with animal damage management (ADM), and research.

The purposes of this Memorandum of Understanding are: (1) To identify responsibilities of the respective agencies and foster a partnership in discharging the Federal

obligation under the Animal Damage Control Act of March 2, 1931, (46 Stat. 1468; 7

U.S.C. 426-426b), as amended, for the management of wild vertebrates causing damage on National Forest System (NFS) lands; (2) to establish general guidelines to

assist field personnel in carrying out their ADM responsibilities consistent with policies

of USDA FS and APHIS-ADC; and (3) to strengthen the cooperative approach to

ADM on NFS lands through exchange of information and mutual program support.

II. INTRODUCTION

It is mutually recognized that the management of animal damage on NFS lands is

important and may involve the control of individual animals, or local populations, to

achieve land and resource management objectives. Further, it is mutually recognized

that the tools and procedures available for managing populations must be used in a

professional manner according to a plan developed in compliance with National Environmental Policy Act (NEPA), National Forest Management Act (NFMA), and Animal

Damage Control Act.

Both agencies have a responsibility for limiting damage caused by wildlife, consistent

with other multiple-use values. They also agree that in evaluating the need for, and in

conducting ADM programs, multiple-use values must be considered.

It is also recognized that:

A. The FS is responsible for the management of land under its jurisdiction,

including the identification of how those lands are to be used. The FS is also

responsible for conducting routine ADM (nonpredator control) operations on NFS

lands, including NEPA compliance on these activities.

158
B. APHIS-ADC is the agency with the authority and expertise under the Animal

Damage Control Act of March 2, 1931, as amended, and pursuant to The Rural

Development, Agriculture, and Related Agencies Appropriations Act of 1988 for

providing ADM services. This includes maintaining technical expertise in the science

of animal damage management, control tools and techniques, conducting ADM

research, conducting management programs, and NEPA compliance on activities

related to predator control.

C. All ADM programs on NFS lands will be coordinated with appropriate State

and Federal agencies.

TO IMPLEMENT THE FOREGOING, the parties agree as follows where National

Forest System lands are involved:

Ill. AGREEMENT

The Forest Service shall:

A. Provide for ADM activities to protect permitted livestock, forest resources and

activities in Forest Land and Resource Management Plans.

B. Cooperate with APHIS-ADC in the development and annual review of

Forest-wide ADM plans.

C. When requested, participate in APHIS-ADC NEPA processes.

D. Invite APHIS-ADC participation in NEPA training at the national, regional and

forest levels.

The Animal and Plant Health Inspection Service shall:

A. In cooperatiion with the FS, state agencies, and permittees, evaluate ADM

needs.

B. Develop and annually update ADM annual plans of work in cooperation with

the Forest Service and appropriate State and Federal Agencies, permittees, and

others. With the Forest Service, identify human safety zones and other areas where

mitigation or restriction may be needed to comply with Forest Plans.

C. Inform the FS about ADM requests, management activities and results on

a timely basis.

D. Provide the FS with technical information on recommended ADM tools and

techniques.

E. When requested conduct ADM training sessions for FS personnel.

IV. BOTH AGENCIES AGREE TO:

A. Conduct ADM on NFS lands in accordance with the APHIS-ADC Policies.

USDA policy on fish and wildlife and consistent with Forest Land and Resource

Management Plans.

B. Form, as needed, State level interagency planning groups with appropriate

State and Federal agencies, permittees, and other cooperators, to assure a mutual

planning effort in each State for developing ADM annual plans of work.

159
C. Develop, as needed, State ADM agreements with the appropriate State and

Federal agencies.

D. Ensure interagency coordination and concurrence on the effects of predator

control activities on National Forest resources before NEPA decisions on predator

control are signed. When BLM lands are also involved, NEPA decisions will be

concurred by FS, BLM, and APHIS officials.

E. Evaluate the ADM program on an annual basis, with emphasis on its

effectiveness in reducing damage by wildlife and meeting the objectives stated in

this MOU.

F. Meet on a State or regional basis annually, or as needed, to coordinate ADM

operations. Representation will be by the FS Regional Forester and the APHIS-ADC

Regional Director, or their designated representatives.

G. Review and resolve problems regarding implementation of this agreement

that arise and cannot be resolved at the field level by elevating to the next higher

level for prompt action.

H. Conduct an annual meeting of the APHIS-ADC Deputy Administrator and

the FS Deputy Chief for National Forest Systems, or their representatives, to

coordinate ADM activities.

I. Cooperate on ADM research of mutual interest.

J. Nothing in this Memorandum of Understanding is intended to modify in any

manner the present cooperative programs of either Agency with States, other public

agencies, or educational institutions.

K. This MOU shall supersede all existing Federal MOUs, supplements, and

amendments thereto relating to the conduct of animal damage control programs with

the parties, with the understanding that all cooperative animal damage control

programs now in progress, shall be incorporated and continued under this MOU if

agreeable to both agencies.

L. This MOU is neither a fiscal nor a funds obligation document. Any endeavor

involving reimbursement or contribution of funds between the Parties of this MOU will

handled in accordance with applicable laws, regulations, and procedures including

those for Government procurement and printing. Such endeavors will be outlined in

separate agreements that shall be made in writing by representatives of the Parties

and shall be independently authorized by appropriate statutory authority. This MOU

does not provide such authority.

M. No member of, or Delegate to, Congress shall be admitted to any share or

part of this MOU, or any benefits that may arise therefrom; but this provision shall not

be construed to extend to this MOU if made with a corporation for its general benefit.

N. Nothing in this memorandum shall obligate the Forest Service to APHIS to

expend appropriations or to enter in any contract or other obligations.

O. The principal contacts for this agreement are:

160
Robert Nelson

USDA Forest Service

4NW AUD WL&F

P.O. Box 96090

Washington, DC 20090-6090

(202) 205-1275

V. EFFECTIVE DATE

Donald Hawthorne

USDA Animal & Plant Health Insp. Svc.

P.O. Box 96464

Washington, DC 20090-6464

(202) 720-2054

This MOU may be modified or amended upon written consent of both parties or may

be terminated with 30-day written notice of either party. Unless terminated, this MOU

will remain in full force and effect until September 30, 1998, at which time it will be

subject to review and renewal.

IN WITNESS WHEREOF, the parties hereto have executed this MOU as of the last

written date below.

/s/ James C. Overbay 6-18-93

Deputy Chief, Forest Service Date

/s/ Michael C. Gregoine

Acting Administrator, Animal and Plant Health

Inspection Service

6-17-93

Date

161
Appendix 3:

Reprints of Technical Papers

1

 These papers are reproduced as they appeared originally.

162
Campbell, D.L.; Evans, J. 1975. “Vexar” seedling protectors to reduce wildlife damage to Douglas-fir. Wildl. Leafl. 508. Washington, DC: U.S. Department of the

Interior, Fish and Wildlife Service. 11 p.

“VEXAR” SEEDLING PROTECTORS TO

REDUCE WILDLIFE DAMAGE TO DOUGLAS-FIR

By

Dan L. Campbell and James Evans

U.S. Fish and Wildlife Service, Wildlife Research Center

Denver, Colorado 80225

INTRODUCTION

This leaflet describes uses of “Vexar” seedling protectors to reduce clipping and

browsing damage to regenerating Douglas-fir (Pseudotsuga menziesii) by snowshoe

hares (Lepus americanus washingtonii), rabbits (Sylvilagus, sp.), black-tailed deer

(Odocoileus hemionus columbianus) and elk (Cervus canadensis roosevelti). The

information was collected from 1968 through 1974 in a cooperative study with

DuPont, Inc., to develop and evaluate “Vexar” as a conifer seedling protector in

western Washington and Oregon.

ALLEVIATING ANIMAL DAMAGE WITH “VEXAR”

Clipping and browsing damage to Douglas-fir seedlings by hares, rabbits, deer, and

elk is a major cause for delayed regeneration and occasionally reforestation failures

in western Washington and Oregon. Protecting the main stem of newly planted

seedlings or the terminal shoot of established seedlings for 3 to 5 years after

planting, or until seedlings are 100 cm (40 in) tall, minimizes the damage. When

main stems and terminal shoots are protected, clipping and browsing of lateral

branching are usually not a limiting factor to growth or establishment of seedlings.

Other chemical and mechanical methods to alleviate clipping and browsing damage

are not completely adaptable to all damage situations. Available repellents (Evans

1974), for example, are not always effective against deer; they are generally

ineffective against elk, do not protect seedlings throughout the year, must be applied

annually or semiannually to treat new growth, and must be registered for operational

use. Mechanical bud protectors (Hines 1971) are not effective against summer

browsing by deer or winter clipping by rabbits and hares. Exclosures of wire or nylon

fencing (Jones and Longhurst 1958, Mealy 1969) are effective but costly and

aesthetically displeasing.

163
“Vexar” protectors are relatively inexpensive, commercially available devices that

reduce clipping and browsing nearly 100% and are considerably more effective than

chemical repellents (Campbell 1969). In high damage areas (40% or more seedling

damaged), seedlings protected with “Vexar” have produced 11 to 14 m (36 to 47 ft)

more height growth per 100 seedlings per year than unprotected seedlings . In areas

with less damage, “Vexar”-protected seedlings produce 8 m (26 ft) more height

growth than unprotected seedlings. Our findings, demonstrations of Douglas-fir

regeneration in critical damage areas by the U.S. Forest Service, and reports by

other users (Anonymous 1972a, 1972b, 1973, Hunter 1972) have stimulated wide

use of several types of “Vexar” protectors in the Pacific Northwest.

“VEXAR” SEEDLING PROTECTORS

“Vexar” polypropylene plastic netting formed into tubes (Fig. 1) has been extensively

tested and used on Douglas-fir. Mesh patterns are diamond (rigid tubing) and twill

(lay-flat tubing which is more flexible and compressed). Most current use is with the

- Photodisinteqration -

-Transluscent Green-

-BlackDiamond Pattern

Figure 1- “Vexar” seedling protectors-polypropylene netting.

164
rigid variety. Mesh openings and angles are illustrated to show the different rates of

protrusion by terminal shoots-the design with 7” terminal protrusion least affects

lateral branch development during early stages of seedlings growth. Ultraviolet

radiation degrades the different colors of “Vexar” netting at different rates (Fig. 1).

The short-lasting clear material may be used on established seedlings where

protection is needed for only one growing season; the green material gives 2 to 3

years of protection. The translucent green material protects newly planted and

established seedlings for up to 4.5 years. As illustrated, breakdown of black material

(durable for 10 or more years) occurs mostly when netting separates as the tree

outgrows it. However, some trees have grown “around” portions of black netting

before the strands have separated, but we do not believe this will lead to a long-term

effect. Although the black protectors may be reused, the advantage of the clear,

green, and translucent green materials is that they split (twill pattern) or degrade

(diamond pattern) before tree growth breaks the netting.

RECOMMENDATIONS

The following recommendations on what, where, when, and how to use “Vexar’

seedling protectors on Douglas-fir are based on the results of Fish and Wildlife

Service studies,

What to Use

“Vexar” polypropylene plastic mesh rigid tubing is recommended over the lay-flat

type. Dimensions with the least overall effect on seedling growth and form are:

Inside diameter: 5 cm (2 in) Strand diameter: 1.5 mm (60 mils)

Mesh opening: 9 mm (3/8 in) No. of strands: 1.3/cm (2/in)

Mesh angle: 70 Color: Translucent green: 5% UVI

The material is available through DuPont, Inc., Specialty Markets Division, Vexar

Sales, Brandywine Building, 89247, Wilmington, Delaware 19898. DuPont’s code for

this tubing is 2-in ID 60-PDP-27, translucent green. Occasionally, finished products

do not conform to the measurements given. Minimum-maximum mesh openings can

be 6 to 9 mm (1/4 to 3/8 in), but other dimensions should be as listed above. Cost

per 0.3 m (1 ft) of this tubing in 1974 was about $0.05.

Where and When to Use “Vexar”

“Vexar” seedling protectors can be used wherever browsing and clipping occur. We

recommend they be used where: (1) severe damage occurs or is expected to occur,

(2) damage occurs during all seasons or by several species of wildlife, and (3)

restocking is necessary because of seedling loss to wildlife. If these conditions exist

or are expected, “Vexar” tubes offer better short- and long-term protection than any

available animal repellent.

165
How to Use “Vexar”

There are several ways of applying “Vexar” for protecting the main stem of Douglas-fir

seedlings (Fig. 2). Most protectors are applied after the seedling is planted by fitting

rigid tubing over the entire seedling. Position of lateral branches is not important as

long as the main stem is approximately centered. On most newly planted 2-year-old

seedlings, wire pins, staples, or a wooden lath should be used to anchor and support

the protector; on sturdy seedlings, the lateral branches lend the necessary support.

When elk are causing damage, protectors should also be secured with a twist-tie.

Partially buried tubes are self-supporting and are used for “containerized” seedlings

by fitting them inside the tubes for planting time. Twill or lay-flat tubing generally

needs more support such as the double lath/twist-tie support as diagrammed (Fig. 2),

although single lath support has been used in some instances.

Our recommended applications of “Vexar” rigid tubing on newly planted and established seedlings are shown in Fig. 3. Newly planted seedlings should be fitted with

tubes 92 cm (36 in) long during or shortly after planting. Wire pins are recommended

for support. Vertical placement of pins and tubing (kept rounded at the base) is

essential to provide support and retention and to minimize terminal protrusion. The

wire-pin/ridge-tube method reduces problems associated with other materials and

methods of installation (Fig. 4).

Heavily browsed established seedlings usually need tubes only 46 cm (18 in) long

placed over the terminal shoot. The tube is pressed down over the main stem to

catch several lateral branches, then gently raised until about half of the tube clears

the terminal as illustrated (Fig. 3). Where elk are a problem, twist-ties are recommended to secure the tube to one or more lateral branches. Tubes can be pulled

upward for additional protection of terminals when needed. Tubes on established

runt seedlings should be supported with wire pins.

COST OF USING “VEXAR”

The cost of using “Vexar” protectors will vary with the methods of installation,

differences in seedling stocking rates (from 200 to 1,000 or more seedlings per acre),

and differences in time and difficulty of installing “Vexar” in various terrain. However,

in 1974, we made some material-labor cost comparisons between our recommended

use and a commonly used double-lath support installation method under ideal

conditions. Costs were as follows using 1 m long, translucent-green tubes ($0.15

each) and assuming labor costs of $5 per hour:

 I r

support

Method Material Man-hours

Estimated

Labor @

$5 per hour

Estimated Cost

of Material

+ Labor

Wire pins

Double lath/

twist-ties

$20.00 1.0 $ 5.00 $25.00

$35.00 2.5 $12.50 $47.50

166
Figure 2-"Vexar" tubes-application/support methods.

OVER NEWLY PLANTED l m- ON ESTASLISHED

STOCK

-2%. Placement 1 1-2Years

Protection or Until Seedling is 40-inches Tall.

Figure 3-Recommended application on Douglas-fir.

Figure 4-Pins/rigid tubes reduce many problems.

167
Costs for protecting 400 seedlings per acre would be about $100 for

wire-pine/rigid-tubing compared to about $190 for double-lath/twist-tie/rigid-tubing.

Cost of the short 46 cm (18 in) tube in 1974 was about $0.08 each. Labor for

installing short tubes over terminals without twist-ties is estimated at $5 per 100, and

with twist-ties about $7.50 per 100 seedlings. Total material-labor cost would be

about $13.00 to $15.50 per 100 seedlings.

SOME OBSERVED PROBLEMS

Several problems that have developed with “Vexar” seedling protectors (Fig. 5) have

been related mostly to improper installation or materials. These can be minimized or

prevented by following our recommendations. Some problems such as tubes or seedlings buried by mud, or breakage by trampling, are unavoidable, but rarely occur.

Installation during freezing weather should be avoided because “Vexar” becomes

brittle and is easily broken.

MISCELLANEOUS INFORMATION

In this section, we attempt to answer questions that are regularly asked about the

use of “Vexar” seedling protectors.

“Vexar” has been widely used in the Pacific Northwest and elsewhere, mainly on an

experimental basis. However, one National Forest in Oregon has begun operational

use with lath-supported tubing; others-as well as State and private organizations in

the Pacific Northwest-are expected to begin operational use in the near future.

Seedling protectors are being tried on other softwood and hardwood timber species

in western, as well as eastern and southern forests, and in windbreak and fruit

orchard plantings in several parts of the United States. Forest managers in other

countries, including Russia and Poland, are experimenting with “Vexar.” Polypropylene netting other than DuPont’s “Vexar” is also being evaluated in the United States,

but we have no information on effectiveness and costs of these products.

There are indications that “Vexar” is also effective in reducing damage to Douglas-fir

by small rodents and mountain beaver (Aplodontia rufa) and to pines (Pinus sp.) by

pocket gophers (Thornomys sp.). These potential uses are now being evaluated.

Environmental problems and hazards of using ‘Vexar” appear minimal. The protectors

are not an eyesore, and photodecomposition of materials (other than black) is quite

rapid and complete following the designed life-span. There is no environmental contamination by polychlorinated biphenyls (PCS’S) in the breakdown of “Vexar’

(DuPont, Inc., personal communication).

Biologically, “Vexar” protectors on individual seedlings benefit both Douglas-fir and

wildlife. Seedlings are protected until they outgrow their plant and animal competitors,

and access to areas by wildlife is not restricted. Vegetation immediately adjacent to

protected seedlings is often browsed, reducing competition and the need for

herbicide treatment.

168
--Man and Material1

-Improper Installation- -Poor Rigidity-

(Split Tubes/Sheeting)

- Animal and NatureMainly Elk

Mud Slide Trampled below 0

oC.

Figure 5-Some problems with “Vexar” tubes.

THE OVERALL EVALUATION OF “VEXAR”

In summary, “Vexar” protectors: (1) are an inexpensive and available method which

greatly reduces clipping and browsing on dormant and growing Douglas-fir seedlings,

(2) are made of photodegradable material which deteriorates in a few months to

several years, (3) are designed so that seedling height growth and form are not

impaired, and (4) are nonhazardous to the forest ecosystem, domestic animals, or

man. “Vexar” seedling protectors fill the need to offset wildlife damage to

regenerating Douglas-fir, and are being well accepted as a nonchemical and

environmentally safe approach to forest-animal damage control.

ACKNOWLEDGMENTS

Cooperators, in addition to DuPont, Inc., included the State of Washington,

Department of Natural Resources, particularly L.E. Johnson and H.D. Hartwell;

personnel of the U.S. Forest Service on several National Forests and at the

Equipment Development Center at Missoula, Montana; Weyerhauser Co.; Simpson

Timber Co.; and Oregon State University.

169
LITERATURE CITED

Anonymous. 1972a. A new seedling protection device reduces seedling losses,

enhances growth. Forest Industries, June 1972, p. 51.

Anonymous. 1972b. A new seedling protection device reduces seedling losses,

enhances growth. World Wood. October 1972, p. 85.

Anonymous. 1973. Protection from browsing. For. Chron., April 1973, p. 62.

Campbell, D.L. 1969. Plastic fabric to protect seedlings from animal damage. Pages

87-88 in H.C. Black, ed. Wildlife and Reforestation in the Pacific Northwest,

Symposium Proc., 1968. Oregon State Univ., School of Forestry, Corvallis.

Evans, J. 1974. Pesticides and forest wildlife in the Pacific Northwest. Pages

205-219 in H. C. Black, ed. Wildlife and Forest Management in the Pacific Northwest,

Symposium Proc., 1973. Oregon State Univ., School of Forestry, Corvallis.

Hines, W.W. 1971. Physical versus chemical means of deterring browsing of

Douglas-fir by black-tailed deer. Tree Planters’ Notes 22(2):9-13.

Hunter, J.D., ed. 1972. Fending off foragers. DuPont Magazine, January-February

1972, 66(1):24-25.

Jones, M.M. and W.M. Longhurst. 1958. Overhanging deer fences. J. Wildl. Manage.

22(3):325-326.

Mealy, R.H. 1969. Nylon fencing to protect plantations from damage by big game.

Pages 89-90 in H.C. Black, ed. Wildlife and Reforestation in the Pacific Northwest,

Symposium Proc., 1968. Oregon State University, School of Forestry, Corvallis.

Additional information on the above topic is given in the following document:

Larson, J.; Campbell, D.; Evans, J.; Lindsey, G. 1979. Plastic tubes for protecting

seedlings from browsing wildlife. ED&T 2217. Missoula, MT: U.S. Department of

Agriculture, Forest Service, Equipment Development Center. 19 p.

Where discrepancies exist between recommendations given by Campbell and Evans

and those given in the Larson paper, follow the updated information given in the

latter.

170
deCalesta, Davis S. 1985. Estimating cost-effectiveness of controlling animal

damage to conifer seedlings. In: Bromley, P.T., ed. Proceedings, 2d Eastern

wildlife damage control conference; 1985 September 22-25; Raleigh, NC. Raleigh,

NC: North Carolina State University: [pages unknown].

[Author’s address in 1993: USDA Forest Service, Forestry Sciences Laboratory,

Box 928, Warren, PA 16365.]

Estimating Cost-Effectiveness of Controlling Animal Damage to

Conifer Seedlings

David S. deCalesta

Abstract

A model for determining the benefit-cost ratio of controlling damage by vertebrate

pests to conifer seedlings requires knowledge of the amount, distribution, and

duration of animal damage, reduction in damage associated with control, costs of

control, methodology and value of trees at harvest. Because control costs occurring

in the present must be compared with savings recovered decades later in the future,

the model incorporates procedures for discounting or adjusting future monetary

benefits into present net worth valuations. The model allows forest managers to

evaluate a wide range of damage costs and savings accruing from use of various

control techniques. The model clearly demonstrates that application of controls

before damage occurs is more cost-effective than withholding application until it is

established that damage will occur.

Introduction

Damage by vertebrate pests to conifer seedlings is a significant economic loss to the

timber industry in the Pacific Northwest (Lawrence 1958, Swift 1960, Dimock and

Black 1969, Brodie et al. 1979). The pests have been identified (Lawrence et al.

1961, US. Dept. Agric. 1978) and the frequency and distribution of damage, the percentage of trees killed, and the effect on subsequent tree growth have been reported

(Munger 1943, Staebler et al. 1954, King 1958, Crouch 1968, Dimock 1970, Mitchell

1974, Black et al. 1979, Evans et al. 1981). There is only one report that provides

guidelines for timing of application of controls to reduce or eliminate damages, and

that concerned only bear damage to second-growth conifers (Schreuder 1976). One

criterion that could prove useful in such decisions-and which we can model and

which Schreuder (1976) used-is the benefit-cost ratio.

Benefit-Cost Ratio

We need two figures to estimate benefit-cost ratio: first, cost of control methods;

and second, savings resulting from application of those methods. If the savings, in

dollars, are higher than the costs, the benefit-cost ratio is greater than 1, and control

methods will more than pay for themselves.

Costs of control are fairly easy to compute, as they are generated over a short time,

usually less than two years; and they are obvious, usually including labor, travel,

equipment and/or materials, and administration.

171
Savings are more difficult to estimate, because managers must predict how much

damage will occur without control and how much damage the control method will

eliminate. To avoid this difficulty, the control program may be delayed for a year.

Rate of first year damage can be documented and assumed as that for subsequent

years. For smaller pests permanently residing on regeneration sites such as mountain

beaver (Aplondontia rufa), voles (Microtus sp.), and rabbits (Sylvilagus sp.), this may

be a valid assumption. For larger pests such as deer (Odocoileus sp.), elk (Elaphus

sp.), and bear (Ursus sp.), which may or may not include specific regeneration sites

within a larger, annual home range, rate of damage one year may not be duplicated

in following years.

Some conifer seedlings attacked by vertebrate pests die while others are set back in

growth, so estimates of damage must include the value of trees destroyed and lost

before commercial thinning or final harvest, and the value of reduced volume of trees

damaged but not killed. More trees are planted on regeneration sites than are

removed at final harvest; the remainder are removed at commercial thinning (for a

commercial value), and by mortality factors including insects, disease, and vertebrate

pests.

Thus, proportionate numbers of seedlings killed or damaged by vertebrate pests must

be apportioned to precommercial thinning (no value lost) and commercial thinning

(value lost representation of commercial thinning rather than final harvest) as well as

to final harvest, and representative loss values assigned.

Usually, damage by vertebrate pests to conifer seedlings (and associated application

of control methods) occurs 1-5 years after outplanting, but commercial thinning and

final harvest occur decades later. Thus, costs of control in today’s dollars must be

adjusted for comparison with value of timber saved today, but harvested in the future

and inflated in value above today’s market prices. Adjustment and comparison of

control costs and market values to reflect current comparable values is termed

“present net worth valuation” or “discounting.”

Conventional timber harvest economics dictate calculation of present net worth valuations on timber. Present net worth of timber harvested in the future is derived by

compounding today’s stumpage values for n years (numbers of years to harvest) at

an expected inflation rate (i) and equating it to the value of an investment compounded at today’s interest rates on conventional investments (r) to arrive at the

stumpage value inflated n years into the future. For example, timber harvested in 60

years, worth $100,000 per ha today and inflated by an expected inflation rate of 5%,

is worth $10,000 (1.05) = $1,867,920 per ha, 60 years in the future. This value

must be reverse compounded 60 years back to the present at a current investment

rate, say 8%. Letting X equal the present net worth value of the timber, X (1 .08)60

 =

$1,867,920; solving for X we arrive at the value of $18,447 per ha for the present net

worth of the timber per ha.

Present net worth of the cost of animal damage control methods is calculated slightly

differently. The value of control efforts is equated with that of any ordinary investment,

and assigned the prevalent interest rates plus the current inflation rate, compounded

forward for the period of expected damage (usually less than 5 years) and then back

compounded at the prevalent interest rate. The following calculations, which demonstrate the process of estimating loss to vertebrate pests and determination of the

benefit-cost ratio, are based on present net worth valuations.

172
The Model

Data required to arrive at the benefit-cost ratio include: a) amount, distribution, and

duration of expected animal damage, b) reduction in damage associated with control,

and c) value of trees at commercial thinning and at final harvest. The basic model for

estimating benefit-cost ratios is represented by the equation:

Value of preventable loss ($)

Cost of control ($)

Value of preventable loss (V) may be calculated by multiplying number of trees

projected as damaged or killed by pests and saved by control by the value of trees.

Value of trees varies at several distinct periods. Trees harvested at precommercial

thinning have essentially no market value, whereas trees harvested at commercial

thinning have a value (Vc) which is considerably lower than that for trees cut at final

harvest (Vf).

Trees killed or damaged by vertebrate pests must be assigned, proportionately, to

precommercial thinning, commercial thinning and final harvest.

If K trees are killed or damaged, NP (number of trees cut per ha at precommercial

thinning) trees, divided by Nt (number of trees planted per ha) provides the fraction

(Np/Nt) of K trees killed or damaged assigned to precommercial thinning. By similar

logic (Nc/Nt) equals fraction of K trees killed or damaged and assigned to

precommercial thinning (NC = number of trees cut per ha at commercial thinning) and

Nf/Nt equals fraction of K trees killed or damaged assigned to final harvest (Nf =

number of trees cut per ha at final harvest).

Number of trees saved by control (K) is a function of: 1) the area damaged (D) by

the pest, expressed as a fraction of the total regeneration site; 2) the percent

reduction in volume of trees killed or damaged by the pest (P) in an area of damage,

expressed as a fraction; 3) intensity of damage (I) (number of trees attacked within

area of damage), the number of years (N) damage occurs by the pest(s); and 4)

efficiency of damage control methods (E) expressed as a fraction, reflecting the fact

that control methods are rarely 100 percent effective.

The number of trees saved per ha by control of vertebrate pests (K) can be

estimated by the formula: K = DxPxlxExN.

For the purpose of demonstrating the process of estimating cost-effectiveness, three

periods of tree removal (precommercial thinning, commercial thinning, and final

harvest) are utilized. If fewer or greater periods of tree removal occur on specific

sites, calculation of values will include fewer or more steps, respectively.

If the corrective mode of control (wait until damage occurs before applying control

methods) is utilized, number of trees killed or damaged the first year (Kt

) will not be

saved and subsequent calculations of value of control will be based on trees

potentially saved in the second and succeeding years (K2). Value (V) of the stand will

be lower than when the preventive mode is used because there will be fewer trees

left to harvest after the loss of K1 trees.

Current value of trees saved by application of control methods is computed by

summing the value of proportionate numbers of trees saved from commercial

thinning [K(Nc

/Nt)] and from final harvest [K(Nf/Nt)]. This summed dollar value is then

converted to present net worth value via the discounting procedure described above.

173
Examples

Preventative Control

Assume damage is caused by mountain beaver to Douglas-fir seedlings: trees

attacked suffer 90% reduction in volume (P), damage occurs over 30% of the area

(D), within area of damage 50 trees per ha are attacked (I), and duration of damage

is 3 years (N). Assume control method used is vexar tubing (protect seedlings by

placing sleeve of rigid plastic mesh, 40 cm high, around them at planting) at 95%

efficiency in reducing damages at the cost of $250 per ha.

Number of trees scheduled for commercial thinning represented by these 50 trees is

determined by multiplying 50 by the fraction of all trees represented by those

commercially thinned (470/10000 = 0.47, Table 1), which equals 50x0.47 = 23.5.

Current value of these 23.5 trees saved by application of vexar tubing is: 23.5 trees

[number of trees attacked] (I) in areas of damage] times 0.9 [reduction in volume (P)

of trees attacked] times 0.3 [damage occurs over 30% (D) of area] times 0.95

(efficacy of control method used (E)] times 3 (number of years for which damage is

expected) times $2375/470 (value of each tree saved for commercial harvest). This

value is $91.38. Present net worth of this timber (X) saved by control, assuming

commercial thinning occurs at 15 years and current interest rate on commercial

investments is 8% is: X(1 .08)15 = $91.38(1 .05)15; X = $59.89

Number of trees scheduled for harvest at rotation represented by the 50 trees

attacked per ha of areas receiving damage is determined by multiplying by the

fraction of all trees represented by those harvested at rotation (180/1000 = 0.18)

which equals 50x0.18 = 9.0. Current value of these 9 trees saved by application of

vexar tubes is 9.0 trees [number of trees attacked (I) in areas of damage] times 0.9

[reduction in volume (P) of trees attacked] times 0.3 [damage occurs over 30% (D) of

area] times 0.95 [efficiency of control method used (E)] times 3 [number of years for

which damage is expected] times $9,000/180 (value of each tree saved for

commercial harvest). This value is $346.28.

Present net worth of this timber saved by control, assuming interest and inflation

rates given above and that final harvest is 60 years after planting is: $X(1 .08)60

 =

$346.28(1 .05)60 = $63.88.

Table 1. Data set assumed for estimating losses of trees to vertebrate

pests.

Trees/ha At planting At At At

precommercial commercial final

thinning thinning harvest

(NP) (NC) V W

Standing 1000 650 180 0

cut 0 350 470 180

Value 0 0 $2375 $9000

174
Present net worth of commercially thinned and final harvested timber, saved by

application of control methods is $59.89 + $63.88 = $123.77 per ha.

Present net worth of vexar tubing is $X(1 .05)3

 = $250(1 .08)3; X = $272.05.

Benefit:cost ratio = $123.77/$272.05 = 0.45. This value is less than 1.0, so control of

damages by vexar tubing, when damage is anticipated for 50 trees, is not cost

effective. Multiplying the benefit:cost ratio of 0.45 by 2.2 yields a benefit:cost ratio of

1.0; multiplying any of the values used to compute K (D, P, I, E, or N) by 2.2 will

result in a benefit:cost ratio equal to or greater than 1.0. Increasing the I value (50)

by a factor of 2.2 (2.2 X 50 = 111) results in a number of trees saved that would be

cost effective. Increasing the values of 2 or more of the values by factors whose

product equals 2.2 will also result in a benefit:cost ratio greater than 1.0: If the D

value is increased by 1.75 and the I value by 1.25 (1.75 x 1.25 = 2.2) resulting

benefit:cost ratio is greater than 1.O.

Corrective Control

Using the same values as the above example, excepting that no controls are effected

the first year of damage, 111 trees per ha will be lost the first year. These 111 trees

will represent 111(470/1 ,000) = 52.2 fewer trees available for commercial thinning

and 11(180/1,000) = 20.0 fewer trees available for final harvest.

Value of commercially thinned trees will decrease per ha by an amount commensurate with the reduction in number of trees left to save ($2,375 per ha x 417.8/470 =

$2,111.2 per ha). Likewise, value of timber at final harvest will decline to $8,000 per

ha. Thus, for the second year of damage fewer trees will be left to save and value of

saving the 111 trees will be less. Indeed, present net worth of saving 111 trees the

second year is $192.95 per ha. Present net worth of applying vexar tubing for 2 years

is $192.59/264.49 = 0.73.

Thus, delaying implementation of control for one year, with a constant damage level,

results in a benefit:cost ratio that is no longer cost effective; corrective control programs, which require waiting one year to assess level of damage before applying

controls, are less cost effective than preventive control programs. The implication is

obvious: if models were available that allowed prediction of damage by vertebrate

pests of conifer seedlings, application of damage control methods would be more

cost effective and savings would increase.

The increased use of personal computers, and spread sheet software, should make

models such as this one tremendously useful to managers in planning animal damage

control programs: multiple evaluations of benefit:cost ratios can be computed rapidly

and cheaply so that upper and lower limits of parameters influencing benefit:cost

ratios, such as efficiency of control method, or reduction in volume of trees damaged

by a pest, can be evaluated to determine a range of damage characteristics within

which animal damage control efforts will be cost effective.

175
Literature Cited

Black, H.C., E.J. Dimock II, J. Evans, and J.A. Rochelle. 1979. Animal damage to

coniferous plantations in Oregon and Washington. Part 1. A survey. Res. Bull. 25,

For. Res. Lab., Oregon State Univ., Corvallis. 45 p.

Brodie, D., H.C. Black, E.J. Dimock II, J. Evans, C. Kao, and J.A. Rochelle. 1979.

Animal damage to coniferous plantations in Oregon and Washington. Part II. An

economic evaluation. Res. Bull. 26, For. Res. Lab., Oregon State Univ., Corvallis.

24 p.

Crouch, G.L. 1968. Spring-season deer browsing of Douglas-fir on the Capital Forest

in western Washington. Res. Note 84. U.S. For. Serv. Pac. Northwest For. Range

Exp. Stn. 8 p.

Dimock, E.J. II, and H.C. Black. 1969. Scope and economic aspects of animal

damage in California, Oregon and Washington. P.10-14 in Wildlife and Reforestation

in the Pacific Northwest, Symposium Proc. (H.C. Black, ed.) School of Forestry,

Oregon State Univ., Corvallis.

Dimock, E.J. II. 1970. Ten-year height growth of Douglas-fir damaged by hare and

deer. J. For. 69:285-288.

Evans, J., D.L. Campbell, G.D. Lindsey, V.G. Barnes, Jr., and R.N. Anthony. 1981.

Distribution of animal damage in southwestern Oregon forests. U.S. Dept. Interior

Wildl. Leaflet 514. 12 p.

King, J.E. 1958. Development of a stand of coniferous reproduction and interplanted

Douglas-fir. Northwest Sci. 32:1-8.

Lawrence, W.H. 1958. Wildlife-damage control problems on Pacific Northwest tree

farms. Trans. North Am. Wildl. Conf. 23:146-151.

Lawrence, W.H., N.B. Kverno, and H.D. Hartwell. 1961. Guide to wildlife feeding

injuries to conifers in the Pacific Northwest. West. For. Conserv. Assn. 44 p.

Mitchell, K.J. 1974. Height growth losses due to animal feeding in Douglas-fir

plantations, Vancouver Island, British Columbia. For. Chron. 40:298-307.

Munger, T.T. 1943. Vital statistics for some Douglas-fir plantations. J. For. 41:53-56.

Schreuder, B.F. 1976. Economic decision making in black bear damage control.

Washington For. Prot. Assoc. 1411 4th Ave. Bldg., Suite 1220, Seattle, WA. 98101.

43 p.

Staebler, G.R., P. Lauterbach, and M.W. Moore. 1954. Effect of animal damage on a

young coniferous plantation in southwest Washington. J. For. 52:730-733.

Swift, L.W. 1960. Wildlife management and protection in the forests of the United

States. Proc. World For. Cong. Seattle, WA. 5:1794-1800.

U.S. Department of Agriculture. 1978. Animal damage control handbook. U.S. Dep.

Agric. For. Serv. Regions 5 and 6.

176
Horton, Alan J. 1987. Animal damage prediction models in conifer plantations. In:

Baumgartner, D.M.; Hahoney, R.L.; Evans, J. [and others], eds. Proceedings,

workshop on animal damage management in Pacific Northwest forests; 1987

March 25-27; Spokane, WA. Pullman, WA: Washington State University,

Cooperative Extension: 29-36. Available from: Coop. Extension, Washington State

University, Pullman, WA 99164.

Animal Damage Prediction Models in Conifer Plantations

Alan J. Horton

Silviculturist

USDA Forest Service

Area IV Technology Transfer

2819 Dahlia

Klamath Falls, Oregon 97601

Abstract

Animal damage prediction models are most effective when used by interdisciplinary

teams composed of wildlife biologists, foresters, forestry technicians, and range

conservationists. Foresters usually focus on seedling protection, wildlife biologists on

animal habitat needs, food preferences, and population dynamics, while range

conservationists are most knowledgeable about livestock herd movements and

seasons of use. Together, these disciplines are applied in an integrated way to share

risk, thereby reducing investments in seedling protection.

In south-central Oregon, we have site-specific models for predicting damage by

pocket gophers, big game, and livestock. Pocket gopher and big-game protection has

often exceeded a third of our total plantation establishment costs. Prediction models

are based upon habitat, history/experience, population cycles, weather and

disturbance factors (big game), use patterns and travel routes (big game and

livestock), and available controls.

On districts that have implemented interdisciplinary animal damage management

through the use of prediction models, plantation establishment costs have declined

significantly. However, we have failed to accurately predict damage on a few

plantations. Failures have been essential to testing the limits of the models. Ongoing

refinement of the models is necessary, particularly in separating “high risk” from

“moderate risk” conclusions. As interdisciplinary animal damage risk management

has gained acceptance, we have experienced increasing needs for more frequent

plantation monitoring.

Samples of animal damage prediction models along with names and addresses of

some of our modelers follow this abstract.

177
DISTRICT

SALE

SOIL TYPE

DATE

MULTIPLY YES’S X WEIGHT

YES

or SUBNO SCORE WT. TOTAL

1. SOILS FAVORABLE FOR BURROW SYSTEM DEVEL. 9 2

(clay loams, granitics, pummies)

2. SOILS WILL LIMIT BURROW SYSTEM DEVELOPMENT. 3

(heavy clay %, seasonal drainage limitations)

3. SOIL NOT FAVORABLE FOR BURROW *NO GOPHER PROBLEMS

SYSTEM DEVELOPMENT. (very heavy “gumbo” clays)

l MUST FIELD-VERIFY BOTH UNIT AND PERIMETER AREA.

VEGETATION TYPES

4. SITE MESIC W/RHIZOMATOUS PLANTS AND

SUCCULENT FORBS.

5. SITE IS ADJACENT TO ABOVE HABITAT

6.* MIXED CONIFER/SNOWBERRY/FORBS

8.* MIXED CONlFER/SNOWBERRY/lWINFLOWER

*PLANT ASSOCIATIONS

SNOW ACCUMULATION

9. ANNUAL SNOW ACCUMULATION < ONE FOOT.

10. ELEVATION <4000 FEET AND SNOW ACCUMULATION

> ONE FOOT.

11. ELEVATION >4000 FEET AND SNOW ACCUMULATION >

ONE PACK UNTIL MAY.

SLOPE

1.>35%

13. < 35%

14. < 10%

HISTORY OF POCKET GOPHER DAMAGE

15. < 50% OF COMPARTMENT CUTOVER WITH HISTORY

OF POCKET GOPHER DAMAGE.

16. HISTORY OF POCKET GOPHER DAMAGE TO SEEDLINGS

IN AREA.

17. POCKET GOPHER DAMAGE PRESENT ON SITE OR

ADJACENT AREA.

18. SITE ADJACENT TO MEADOW/GLADE WITH GOPHER

ACTIVITY.

ANTICIPATED

5 5

3

10

10

1

3

5 (01 USE IO)

2

1

3

10

10

2

5 10

10

15

178
SITE PREPARATION 5

19. LITTER (DUFF, NEEDLES, ETC.) WILL COVER 50% 1

OR MORE OF UNIT.

20. SITE PREPARATION 100% VIA SCARIFICATION 5

OR BROADCAST BURN.

21. UNIT WILL BE SEEDED WITH FORBS/SUCCULENT 3

GRASSES.

REFORESTATION FACTORS 5

22. REPLANT OR FILL-IN PLANT 5

23. NATURAL REGENERATION l 8

24. YEARS SINCE HARVEST OR BURN:

2

5

10

1-3

3-5

> 5

* UNLESS NATURAL REGEN. IS PREDICTABLE

WITHIN THE FIRST 2 YEARS.

POCKET GOPHER PREDICTION MODEL RISK ASSESSMENT

TOTAL POINTS DAMAGE POTENTIAL

<50 LOW POTENTIAL FOR MORTALITY/GROWTH LOSSES.

50-75 LOW TO MODERATE RISK OF DAMAGE. NEED TO

MONITOR GOPHER POPULATIONS.

75-125 MODERATE TO HIGH RISK. NEED MORE

EXTENSIVE SURVEYS. SEEDLING DAMAGE

COULD BE HIGH IN SPOTS.

125-200 DAMAGE RISK HIGH. MORTALITY OF CROP TREES

EXPECTED. NEED CLOSE MONITORING, DAMAGE

CONTROL MEASURES LIKELY. NEED TO CONSIDER

CUMULATIVE EFFECTS OF MORTALITY FACTORS.

200+ DAMAGE RISK EXTREMELY HIGH. INTEGRATED

PEST MANAGEMENT SHOULD BE CONSIDERED, THAT

IS, HERBICIDES, LOCATION OF UNIT, TYPE OF

HARVEST, LEAVE RESIDUE/MINIMIZE FORBS AND

GRASS, ETC.

179
EVALUATION OF DEER/ELK DAMAGE CONTROL NEEDS

(Use for existing plantations, recently cut units, preplanting.)

SALE UNIT DATE

Criteria

Score

(circle 1)

District’s How Useful is this

Place your Criterion to you?

Score Values District’s

Here Value

1. Damage to

Seedlings.

a) more than 35%

b) 10-35%

c) less than 10%

2. Stocking

a) 20% or more

below recommended

level.

b) Within 20% of

recommended level.

c) Exceeds 20%

recommended level.

3. Seedling Size

a) Under 18” tall.

b) 19” - 36” tall.

c) Over 36” tall.

4. Species

a) Mostly Douglas-fir

b) Mixed Conifer.

c) True Fir.

5. Amount of Sign

a) Abundant tracks,

droppings.

b) Moderate.

c) Very little.

6. Accessibility

a) Light slash/debris,

few obstructions.

b) Moderate to heavy

slash obstructions.

5

3

1

2

1

High

High

High

High

Medium

Low

180
7. Isolation Factor

a) People often

present or pass by. 2

b) People occasionally

present or pass by. 1

8. Stock Type (Only use for

units planted within 1 yr.)

a) Containers.

b) 1-0 bare root.

c) 2-0 bare root.

Summary of Score Value

Low

High

Evaluation. Recommendation

All Criteria Criteria

Used 1 - 7 Used

18+ points (15+ points) Damage will be extensive,

control measures should

be taken.

8-18 points (7-15 points) Damage control should be

considered, especially if

stocking level is low and

trees are small.

0-8 points (0-7 points) Damage control is not

recommended.

181
SALE

Criteria

DEER/ELK ANIMAL DAMAGE PREDICTION MODEL

(Use in the sale planning phase)

UNIT DATE

District’s How Useful is this

Place your Criterion to you?

Score Score Values District’s

(circle 1) Here Value

1. Unit is within 4

migratory corridor.

2. Unit is within summer 5

range; bedding, feeding,

movement areas present.

3. Unit is within winter 1

range.

4. History of area 3

reflects high to

medium deer/elk

densities.

5. Evidence of browsing 3

on natural regeneration.

6. Evidence of browsing 5

on nearby plantations.

7. Abundance of tracks, 4

droppings, trails.

8. Disturbance to elk; 1

area frequently used

by people.

9. Units have little to 1

moderate slope.

10. There are few obstruc- 1

tions to movement,

light slash and brush.

11. Snow recession 3

coincides with spring,

migration animals closely

follow the snow line.

12. Drainage is less than

30% cutover.

1

TOTAL (summary of circled numbers)

182
I

EVALUATION RECOMMENDATION

I - -

22+ points

16-22 points

10-16 points

0-10 points

Prescribe control measures, damage could be extensive.

Damage control may be indicated, damage is predicted.

Damage control should be considered, expect some

damage.

Animal damage is not anticipated to be a problem,

control is not recommended.

183
Black, Hugh C. 1989. Vertebrate pest management in Pacific Northwest forests. In:

Protecting the health of Pacific Northwest forests through integrated pest management: a symposium for forest managers; 1989 January 17-18; Corvallis, OR.

Corvallis, OR: Oregon State University: 1- 12.

Vertebrate Pest Management in Pacific Northwest Forests

Hugh C. Black

Introduction

Scope and Significance of Animal Damage

Animal damage is a significant and costly problem to stand establishment and

management in the Pacific Northwest. It costs the forest industry millions of dollars

annually (Brodie and others 1979), and is the leading cause of plantation failure in

Oregon (Campbell and Evans.1984). A survey, in 1984, of four western Regions of

the USDA Forest Service showed that animal damage was a serious problem to

forest regeneration and other resources in the Regions surveyed (U.S Department of

Agriculture, Forest Service, Timber Management. March 1984. Washington, DC.

Unpubl. report.).

In 1984, these Regions conducted annual damage control on about 100,000 acres of

plantations and young stands each year. Direct control costs exceeded $5.5 million

per year. An additional 8,000 to 10,000 acres per year required replanting, principally

because of animal damage, at an additional cost of $3.5 million per year.

Animals causing damage to regeneration in these Regions, ranked in order of

importance, are pocket gophers, mountain beaver, deer and elk, and black bear.

Pocket gophers (Thomomys sp.), which are the most destructive species, damage or

destroy regeneration on hundreds of thousands of acres of forest land in the western

United States each year (Crouch 1986).

Present animal damage control practices emphasize direct population control

(baiting, trapping and snaring, and special hunts) and use of physical barriers (plastic

mesh tubing and fencing). But these practices are limited in effectiveness, costly, and

becoming increasingly restricted by regulations and the public’s concerns regarding

their use. Of particular concern is the potential impact on threatened and endangered

species and other nontarget species, and concerns are growing regarding animal

welfare. These latter concerns are expressed through restrictions on use of leg-hold

traps, e.g., leg-hold traps are banned in New Jersey, and use of snares to take bears.

Reforestation Success

Animal damage may be receiving less attention from forest managers because of the

overall success of reforestation in recent years. For example, over the last 5 years

(1981-1986), an average of 88 percent of all reforestation on National Forest System

(NFS) lands have met stocking objectives. In 1986 (the latest year for which data are

available), success was 91 percent (USDA Forest Service 1988). This pattern of

successful reforestation is also occurring on industrial, state, and other federal forest

lands. The numbers of acres reforested each year is also growing because of

increased timber harvesting and severe wildfire damage in the West in both 1986

and 1987.

184
In 1987, the USDA Forest Service reforested 394,000 acres of NFS lands-the

highest number of acres reforested since 1981 (USDA Forest Service 1988). This

increase in reforestation was outpaced by the increase in acreage needing

reforestation. At the end of 1987, about 1.1 million acres of NFS lands needed

reforesting. This increase (over previous years) occurred primarily because of record

high timber harvesting levels, the extreme wildfire damage in California and Oregon

(in 1987), and severe bark beetle infestions in northeastern Utah.

Current Pest Management Practices and Their Limitations

Current vertebrate pest management practices are limited for the most part to use of

a small number of chemical toxicants and repellents, and physical barriers (mainly

plastic mesh tubing), which have been available for many years. For example,

hand-baiting with strychnine oat baits to control pocket gophers-the most commonly

used practice today-was adapted directly from agricultural practices developed in

the early 1900s (Lantz 1903, Crouch 1933). Use of burrow builders for control of

forest pocket gophers, which was also adapted from agricultural uses, first occurred

in the 1960s (Ward and Hansen 1962). Crouch (1986) observed that hand- and

machine-baiting, with strychnine as the toxicant, is still the only effective control

method for large-scale gopher control programs, and procedures have changed little

over the past 80 years.

Tetramethylthiuram disulfide (TMTD or Thiram), one of the two most widely used

foliar repellents for protection of conifer seedlings from clipping by hares and rabbits

and browsing by deer and elk, was first used operationally for this purpose in the

1960s and became the “standard” for evaluation of other candidate repellent

compounds (Kverno and others 1965). Use of this repellent has recently declined,

however, because of possible human toxicity (Campbell and Evans 1984).

Big-game repellent (BGR) was developed more recently (Rochelle and others 1974).

“Vexar” seedling protectors (plastic mesh tubing) also were introduced at about the

same time (Campbell and Evans 1975). In the meantime, several chemicals

(toxicants and repellents) that had been used operationally or experimentally to

protect conifer seeds or seedlings from animal damage are no longer available for

these purposes. Examples of seed protectants no longer available include Compound

1080 (sodium fluoracetate), endrin, mestranol, and thallium sulphate. Examples of

seedling protectants no longer available include octamethylpyrophoroamide (OMPA)

and Gophacide.

Among the reasons for the unavailability of these and other chemicals are failure to

obtain EPA registration (OMPA), the compound is registered but commercially

unavailable because of limited market (Gophacide), or use is restricted by the EPA,

e.g., the recent temporary cancellation of all above-ground uses of strychnine for

rodent control (Federal Register, Vol. 53, No. 193, October 5, 1988).

OMPA is a highly toxic compound that was successfully used operationally as the

active ingredient in a toxic tracking foam to control mountain beavers in Washington

(Oita 1969) and used experimentally as a systemic animal repellent (Rediske and

Lawrence 1964). (A systemic repellent is a chemical applied to foliage, roots, or soil

that is absorbed and translocated to all parts of the seedling, and limits feeding on

the plant by animals; Rochelle 1973). It was not federally registered, however,

because of its extreme toxicity and potential hazard to nontarget species.

Development of New Vertebrate Pest Management Tools

185
An array of vertebrate pest management tools is required because they often are

most effective when used in combination, constraints may limit use of certain

methods, or development of resistance to particular chemicals may require use of

alternative techniques. But development of new pest management tools and

techniques has lagged for several reasons (Spencer 1982): forest management

requires only small amounts of chemicals and is considered a “minor use,” it is

becoming more and more time consuming and costly to register new pesticides (5 to

10 years and several million dollars), and lack of public support for development and

use of pesticides.

Restrictions on Pesticide Use in Vertebrate Pest Management

Pesticide label restrictions-In 1982, in a paper on “Vertebrate pest management

and changing times,” Spencer (1982) emphasized the extent to which restrictive

pesticide labeling to protect endangered species can impact vertebrate pest management. Among several examples, he cited the M-44 registration, which has 26 separate

restrictions, and label restrictions on a rodent burrow fumigant.

M-44 (item 9): “The M-44 device shall not be used in areas where threatened or

endangered species might be adversely affected. Each applicant shall be issued a

map which clearly indicates such areas.”

Endangered species considerations for a rodent burrow fumigant (Degesch -

Mag-Disc) exclude its use within the habitat of six widely distributed endangered

species (from the California condor to the Eastern indigo snake) and require

consultation with FWS Endangered Species Specialists or contact with State Fish

and Wildlife Departments before use of the product.

The pesticide label for pocket gopher bait for use in burrow builders, which was

revised in November 1988 after the EPA temporarily cancelled all above-ground uses

of strychnine (Federal Register, Vol. 53, No. 193, October 5, 1988), provides a

further example of the pervasive influence of endangered species considerations in

vertebrate pest management:

Before baiting, the user is advised to contact the Regional U.S. Fish and

Wildlife Service (Endangered Species Specialist) or the local Fish and Game

Office for specific information on endangered species. Strychnine baits should

not be used in the geographic ranges of the following species, except under

programs and procedures approved by the EPA: California condor, San Joaquin

kit fox, Aleutian Canada goose, Morro Bay kangaroo rat, gray wolf, grizzly bear,

and salt marsh harvest mouse.

For the USDA Forest Service and other federal agencies, this requires formal or

informal biological evaluations and consultations with the FWS and subsequent

jeopardy or nonjeopardy opinions by the FWS before these products may be used

within the geographic ranges of the endangered species listed.

EPA’s Endangered Species Protection Program

In 1986, the U.S. Environmental Protection Agency (EPA) initiated an effort to comply

more fully with the Endangered Species Act (ESA) with regard to regulation of

pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)

(Witt and others 1988).

186
The ESA, which is administered by the FWS, requires federal agencies to ensure

that their actions do not jeopardize the continued excistence of any endangered or

threatened species. Under the ESA, agencies are required to evaluate potential risk

and, when potential effects are identified, to consult with the FWS. If a formal Section

7 consultation is used to obtain a biological opinion, and if the opinion establishes

“jeopardy” to an endangered or threatened species, agencies are required to act to

mitigate risks to the affected species.

Pesticide registration decisions by the EPA, which through the FIFRA registers all

pesticides used in the United States, are based upon evidence adequate to

demonstrate that a pesticide use will not pose unreasonable risks to people and the

environment. Under the ESA, the EPA must ensure that the registered uses of

pesticides within the range of endangered or threatened species will not place the

species or their critical habitats at unreasonable risk. The registration of pesticides is

considered an authorization for use, and thus is subject to the ESA.

As part of their program, the EPA identified clusters of pesticides that could

potentially affect endangered or threatened species. This approach grouped

similar-use pesticides into one cluster. For example, all of the pesticides used in the

management of forest land were grouped into one cluster. In cooperation with the

EPA, the FWS identified federally listed endangered or threatened species potentially

at risk. Pesticide prohibitions and restrictions were then established by the EPA,

under authority of the FIFRA, as amended. To supplement the proposed pesticide

label changes for products in these clusters, the EPA created bulletins and range

maps. These bulletins were to serve to alert pesticide users about counties within

which specific pesticides were prohibited and the endangered or threatened species

at risk. Range maps were intended to depict the currently occupied habitat, or

potential habitat, of each endangered species by county for each prohibited pesticide.

If EPA’s proposed Endangered Species Protection Program had been implemented,

forest pesticide users would have been prohibited from using strychnine and other

rodenticides or predacides (and other pesticides) in areas occupied by listed

threatened or endangered species.

Recent Developments in Vertebrate Pest Management

New Chemicals and Toxicants, and New Bait Formulations

Selenium-In 1983, University of Washington scientists reported that a time-release,

selenium-containing tablet, placed with a seedling when planted, caused the tree to

exude a malodorous gas (“garlic breath”) that repelled deer (Allan and others 1984,

Boling 1984). The plant apparently metabolizes selenium by transforming it into

dimethyl selenide gas (garlic contains selenium) and expels it through the needles,

which may repel deer. Preliminary tests showed that this method could reduce deer

browsing up to 80 percent, with no apparent effect on the tree’s growth rate, and that

it remains effective for three years. (The original concept for the selenium pellet

came from an effort to develop a systemic insecticide to prevent shoot borers from

attacking cedar trees in the tropics.)

187
Field tests of this systemic repellent in Washington, in 1983, failed to confirm

adequate repellency of selenium-treated seedlings to deer. A pen study of deer

browsing of selenium-treated Douglas-fir seedlings by the U.S. Fish and Wildlife

Service was discontinued because seedlings failed to accumulate adequate levels of

selenium. (Campbell, D.L.; Evans, J. 1984. A pen study of deer browsing of

Douglas-fir seedlings treated with selenium deer repellent. Unpubl. Job Completion

Report. Olympia, WA: U.S. Fish and Wildlife Service. 4 p.)

Although the use of systemic insecticides has been highly successful with numerous

commercial applications, development of a systemic animal repellent has intrigued

but, so far, eluded wildlife biologists. Systemic chemicals offer many advantages over

contact repellents, including greater resistance to weathering, potential for protecting

new growth, and potential for providing longer protection (Rediske and Lawrence

1964). Efforts to develop a systemic repellent with OMPA as the active ingredient

(Rediske and Lawrence 1964) and selenium as the active ingredient (Campbell and

Evans 1984) have not been successful.

Synthetic predator odors-Researchers at the Applied Mammal Research Institute

in British Columbia, Canada (Sullivan and others 1988), demonstrated on an

experimental basis that certain synthetic predator odors repelled the snowshoe hare

(Lepus americanus), several species of voles (Microtus sp.), the northern pocket

gopher (Thomomys talpoides), and the red squirrel (Tamiasciurus hudsonicus), and

reduced damage to tree seedlings. Predator odors from the short-tailed weasel

(Mustela erminea) and the red fox (Vulpes vulpes) originating from feces, urine, or

anal scent gland secretions elicited a “fear” response when detected by prey species.

Used as an area repellent, synthetic predator odors produced significant avoidance

responses in the above-named pest species. (Compounds were dispensed in small

capillary tubes attached to trees, which protected them from weathering, controlled

the release of odors, and maintained the odor around the base of test trees.) Field

tests of this new area repellent are currently in progress in forest plantations in

British Columbia.

In a related study designed to assess the influence of predator odors on population

density and survival of montane vole (M[icrotus] montanus) populations in natural

grassland habitat, Sullivan and others (1988) found that vole populations declined in

three consecutive winters on an area treated with predator odors. (They assumed

that odors dispensed from the capillary tubes permeated throughout the treatment

area.) They believed that these declines were caused by significantly lower survival

in the treatment than in the control populations, and attributed this to increased

predation, which may have resulted from the predator odors attracting additional

predators to the study area.

188
Cholecalciferol-QUINTOX (cholecalciferol) is the trade name (Bell Laboratories,

Inc., Madison, Wisconsin) for a new commensal rodenticide, which was registered by

the EPA in December 1987 for controlling Norway rats, roof rats, and house mice

(Brown and Marshall 1988). Cholecalciferol (Vitamin D3) has a different mode of

action than conventional acute and chronic rodenticides. It metabolizes calcium from

bone matrix to plasma, causing target animals to die from hypercalcemia. It differs

from other acute rodenticides in that reportedly no bait shyness is associated with

consumption and once the lethal dose is consumed all food intake ceases, although

time of death may be delayed for 3 to 4 days. Preliminary studies indicate that

cholecalciferol has potential as a rodenticide for controlling pocket gophers and

ground squirrels.

Field-efficacy tests of QUINTOX (pelleted grain baits) on the Targhee National

Forest, Idaho (Personal communication, Jack Amundson, Forest Silviculturist,

Targhee NF, October 1988), were not promising: initial results showed a 35-percent

reduction in pocket gopher activity on the QUINTOX-treated plot compared with a

75-percent reduction on the plot treated with strychnine oat baits. Preliminary tests

on the Umatilla National Forest, Oregon (Bonar, R.E. 1988. Field test of

cholecalciferol on the Heppner Ranger District, Umatilla National Forest, Heppner,

Oregon. Unpubl. report.), were inconclusive. There are indications that poor bait

acceptance may have adversely affected results of both tests.

Durable baits for pocket gopher control-In 1984, researchers at the University of

California, Davis (Tuneberg and others 1984) developed a new concept in pocket

gopher control, which was based on two behaviorial traits of gophers, i.e., their rapid

invasion of unoccupied burrow systems, after the previous occupant has been killed

by a rodenticide, and their use of existing food stores, including baits left by the

previous gopher. They designed and used a long-lasting (i.e., durable) pocket gopher

bait that would not deteriorate for several months in the burrow system. They

anticipated that this approach would make it possible to control gophers with one bait

or a single baiting, and would be well suited in control situations where it is difficult to

locate all of the burrow systems during a hand-baiting operation, and where gopher

invasion from surrounding untreated areas is a problem. Preliminary tests with

cylindrical-shaped paraffinized wheat baits (3 cm x 10 cm) containing bromadiolone,

a potent, second-generation anticoagulant (it produces death in many rodent species

with one or two feedings, unlike the first-generation anticoagulants that require

multiple feedings to be effective) were promising. Gophers moved most baits to the

nest area for feeding, gophers that fed on the baits were killed, and other gophers

rapidly invaded abandoned burrow systems and fed on the residual baits.

In 1987, J. T. Eaton and Co., Inc., Twinsburg, Ohio, applied this concept to the

development of a paraffinized grain bait containing 0.005 percent diphacinone (a

first-generation anticoagulant) for pocket gopher control. Preliminary field tests with

this product, trade-named “Eaton’s Answer,” were promising and provided the basis

for 24-C registrations in several states, including Oregon and Washington.

189
In 1988, the Rogue River National Forest, Oregon, used Eaton’s Answer

operationally for pocket gopher control on 5,800 acres of forest land (Bulkin, S. 1988.

Preliminary results of gopher baiting using durable bait blocks [Eaton’s Answer TM]

containing 0.005% diphacinone. Unpubl. report. Medford, OR: U.S. Department of

Agriculture, Forest Service, Rogue River National Forest.). Preliminary results

showed excellent bait acceptance (95%) and 55 to 65 percent reduction in pocket

gopher activity, based on open hole surveys 2 to 3 weeks after baiting. Baiting with

durable bait blocks was less restricted by weather and soil-moisture conditions than

baiting with strychnine oat baits, but twice as costly. Efficacy of baiting will be

reassessed in the spring of 1989.

Animal damage prediction models-It has long-been recognized that correct

identification of animal damage is the necessary first step in prescribing appropriate

animal damage control methods. Efforts have intensified in recent years to assess

more fully the nature of animal damage problems on a site-specific basis and to

develop species-specific models to predict occurrence of damaging animals, the

extent and distribution of damage, the effects of animal damage on growth, and the

need for damage control. On NFS lands in the Pacific Northwest Region, an interdisciplinary approach has been followed in animal damage assessment and model

development. In their simplest form, these models provide a framework for systematic

problem analysis and evaluation, based on damage history, animal occurrence,

abundance, and use patterns (big game and livestock), and related information on

habitat and plant communities, physical characteristics of the site, site preparation,

etc. Experience has shown that these models are providing better damage assessments and more efficient use of controls, and have reduced plantation establishment

costs (Horton 1987). The Weyerhaeuser Company also has used detailed damage

assessment for evaluating the need for damage control, together with damage prediction models, to reduce damage control expenditures and improve treatment effectiveness (Anderson 1987). Further refinement of existing models and development of

better methods of predicting the extent of damage are needed, however.

Silvicultural Strategies for Vertebrate Pest Management

A team of specialists from Oregon State University, USDA Forest Service research

and management, industry, and others has begun development of a compendium

that will summarize what is known about the response of selected wildlife species

(species that cause damage to forest stands) to limit animal damage. Silvicultural

research needs related to animal damage management also will be identified. This

document (“Silvicultural approaches to animal damage management in Pacific

Northwest forests”) is intended to provide a synthesis of current information to serve

practicing foresters and others as a basis for sound, cost-effective, and environmentally acceptable decisions regarding animal damage management in the Pacific

Northwest. It will provide a comprehensive process for developing silvicultural prescriptions that integrate responses of wildlife species, vegetation, and stand growth in

a manner that leads to preventing or limiting animal damage. It is not intended to

supplant conventional methods of animal damage management, but to emphasize

prevention of damage, while meeting timber, wildlife, and other resource management

objectives. The team is also compiling an annotated bibliography of animal damage

and habitat relationships to provide a useful reference for forest managers and others

concerned with animal damage management.

Vertebrate Pest Management Research

190
During the 1960s and 197Os, vertebrate pest management research was actively

supported, particularly in the Pacific Northwest, by state and federal agencies,

universities, the forest industry, and others. The U.S. Fish and Wildlife Service

conducted an intensive chemical screening program to develop toxicants and

repellents to control forest animal damage (Kverno and others 1965). But this effort

and related research decreased over time because of reduced funding and changes

in research priorities, which were influenced by two compensating trends: (1) the

increasing cost and time required to register new toxicants and repellents, and (2)

the growing success of artificial reforestation due to greatly improved regeneration

systems.

The USDA Forest Service terminated their Animal Damage Control Research Project

at the Pacific Northwest Research Station, Olympia, Washington, in 1975 (Crouch

1987). Although vertebrate pest management research is continuing, supported with

National Agricultural Pesticide Impact Assessment Program (NAPIAP) funds and

other funds, no comprehensive vertebrate pest management research has been

conducted by the Forest Service since 1975. Currently, two cooperative projects,

funded in part with NAPIAP funds, are both aimed at controlling pocket gophers: (1)

“Field-efficacy tests of three concentrations of strychnine baits to control pocket

gophers,” in cooperation with the Animal and Plant Health Inspection Service

(APHIS), Olympia, Washington, and (2) “Environmental exposure and fate of (durable)

multi-kill strychnine gopher baits,” in cooperation with the University of California,

Davis. NAPIAP funding also will be provided to the APHIS, Olympia, Washington,

in 1989, to continue field-efficacy testing of pocket gopher baits (“Field efficacy of

burrow-builder baiting for pocket gopher control”). Each of the field-efficacy studies

will provide data required by the EPA to maintain registrations of strychnine for

below-ground use (hand- and machine-baiting) for pocket gopher control.

Funding and staffing of the USDI Fish and Wildlife Service (FWS) Animal Damage

Control (ADC) Project at Olympia, Washington, had been decreased for several

years before the project was closed in 1985. After transfer of the ADC program from

the FWS to the APHIS in December 1985 (PL 99-130), the project was reactivated in

1986. The APHIS’ present forest ADC research program (both at Olympia and at the

Denver Wildlife Research Center, Denver, Colorado), now in a separate Science and

Technology branch, is beginning to expand after a period of reorganization and

rebuilding. The foremost objective of the research program at Olympia is to maintain

current bait registrations for both pocket gophers and mountain beaver.

Recommendations for Future Action

We need to continue to improve currently available tools and techniques for

vertebrate pest management and, at the same time, to improve how we use them.

More emphasis on developing silvicultural prescriptions that integrate responses of

damaging animals, vegetation, and stand growth, i.e., a silvicultural approach to

animal damage management, will enhance this process.

James L. Stewart, Director of Forest Insect and Disease Research, USDA Forest

Service, in a speech to the Western Forestry and Conservation Association’s Pest

Committee, in December 1988, made the following observations, which are pertinent

to vertebrate pest management:

191
I do not see the environmental community easing up in its role of

challenging the use of current pest-control tactics. Currently registered

tactics will continue to go unused or be employed too late to be

effective in preventing extensive damage because their use excites

controversy. Forest managers will simply not self-inflict the abuse that

comes with trying to employ many of today’s pest control tactics. Where

they do, the delays brought on by appeals and court actions will defeat

the objectives of effective pest management and the result will be

extensive damage.

We have already seen indications of this in vertebrate pest management, especially

in predator control, through restrictions on use of the M-44 and the toxic collar to

control coyotes, and through restrictions on snaring or shooting of black bears

damaging conifer plantations.

Stewart also observed that we need to increase the public’s awareness for the

consequences of not taking action with environmentally compatible control tactics,

but he did not believe we will make much headway in eliminating the constraints. He

observed that the public is not likely to accept routine use of chemicals on public (or

private) forest lands.

Stewart concluded that “we need to give increased emphasis to developing new,

innovative pest-control tactics and strategies that managers can use within the

constraints under which they work. They must be ecologically based and

environmentally and economically sound.”

Literature Cited

Allan, G.G.; Gustafson, D.I.; Mikels, R.A. [and others]. 1984. The reduction of

deer browsing of Douglas-fir (Pseudotsuga menziesii) seedlings by quadrivalent

selenium. Forest Ecology and Management. 7 (1983/1984): 153-181.

Anderson, R.J. 1987. Animal damage prediction and assessment. In: Baumgartner,

D.M.; Mahoney, R.L.; Evans, J. [and others], eds. Proceedings, workshop on

animal damage management in Pacific Northwest forests; 1987 March 25-27;

Spokane, WA. Pullman, WA: Washington State University: 27-28.

Boling, R. 1984. The pill for seedlings; time-release tablet turns a taste treat into a

turn-off for browsing deer. American Forests. 56 (June): 32-32.

Brodie, D.; Black, H.C.; Dimock, E.J., II [and others]. 1979. Animal damage to

coniferous plantations in Oregon and Washington. Part II: an economic evaluation.

Res. Bull. 26. Corvallis, OR: Oregon State University, School of Forestry, Forest

Research Laboratory. 24 p.

Brown, L.D.; Marshall, E.F. 1988. Field evaluation of QUINTOX (cholecalciferol) for

controlling commensal rodents. In: Crabb, C. A.; Marsh, R. E., eds. Proceedings,

13th vertebrate pest conference; 1988 March 1-3; Monterey, CA. Davis, CA:

University of California: 70-74.

Campbell, D.L.; Evans, J. 1975. “Vexar” seedling protectors to reduce wildlife

damage to Douglas-fir. Wildl. Leaf. 508. Washington, DC: U.S. Department of the

Interior, Fish and Wildlife Service. 11 p.

192
Campbell, D.L.; Evans, J. 1984. Wildlife-reforestation problems and seedling

protection in western Oregon: review and current knowledge. Tech. Note OR-4.

Portland, OR: U.S. Department of the Interior, Bureau of Land Managment. 46 p.

Crouch, G.L. 1986. Pocket gopher damage to conifers in western forests: a historical

and current perspective on the problem and its control. In: Salmon, T.P., ed.

Proceedings, 12th vertebrate pest conference; 1986 March 4-6; San Diego, CA.

Davis, CA: University of California: 196-198.

Crouch, G.L. 1987. A bibliography of publications from Forest Service animal

damage research in the Pacific Northwest, 1961-1986. In: Baumgartner, D.M.;

Mahoney, R.L.; Evans, J. [and others], eds. Proceedings, workshop on animal

damage management in Pacific Northwest forests; 1987 March 25-27; Spokane,

WA. Pullman, WA: Washington State University: 9-14.

Crouch, W.E. 1923. Pocket gopher control. Farmers Bull. 1709. Washington, DC:

U.S. Department of Agriculture. 21 p.

Horton, A.J. 1987. Animal damage prediction models in conifer plantations. In:

Baumgartner, D.M.; Mahoney, R.L.; Evans, J. [and others], eds. Proceedings,

workshop on animal damage management in Pacific Northwest forests; 1987

March 25-27; Spokane, WA. Pullman, WA: Washington State University: 29-36.

Kverno, N.B.; Hood, G.A.; Dodge, W.E. 1965. Development of chemicals to control

forest wildlife damage. In: Proceedings, Society of American Foresters; 1965

October 24-28; Detroit, MI: 222-226.

Lantz, D.E. 1903. Destroying prairie dogs and pocket gophers. Expt. Sta. Bull. 116.

Lawrence, KS: Kansas State Agricultural College: 147-163.

Oita, K. 1969. Development and use of toxic foam to control mountain beavers. Part

II. a tracking compound of toxic foam. In: Black, H.C., ed. Proceedings,

symposium on wildlife and reforestation in the Pacific Northwest; 1968 September

12-13; Corvallis, OR. Corvallis, OR: Oregon State University, School of Forestry:

84-85.

Rediske, J. H.; Lawrence, W. H. 1964. Octamethylpyrophosphoramide (OMPA) as a

systemic repellent for Douglas-fir seedlings. Forest Science. 10( 1): 93-103.

Rochelle, J.A. 1973. Wildlife damage control with chemicals. In: Proceedings, forest

pesticides and their safe use. A short course. Sponsored by Oregon State

University and Washington State University, Cooperative Extension Service, and

the U.S. Forest Service, Region 6. 10 p.

Rochelle, J.E.; Gauditz, I.; Oita, K.; Oh, J.H.K. 1974. New developments in

big-game repellents. In: Black, H.C., ed. Wildlife and reforestation in the Pacific

Northwest: Proceedings of a symposium; 1988 September 12-13; Corvallis, OR:

Oregon State University, School of Forestry: 103-112.

Spencer, D.A. 1982. Vertebrate pest management and changing times. In: Marsh,

R.E., ed. Proceedings, 10th vertebrate pest conference; 1982 February 23-25;

Monterey, CA. Davis, CA: University of California: 2-5.

193
Sullivan, T.P.; Sullivan, D.S.; Crump, D.R. [and others]. 1988. Predator odors and

their potential role in managing pest rodents and rabbits. In: Crabb, C.A.; Marsh,

R.E., eds. Proceedings, 13th vertebrate pest conference; 1988 March 1-3;

Monterey, CA. Davis, CA: University of California: 145-150.

Tuneberg, A.D.; Howard, W.E.; Marsh, R.E. 1984. A new concept in pocket gopher

control. In: Clark, D.L., ed. Proceedings, 11 th vertebrate pest conference; 1984

March 6-8; Sacramento, CA. Davis, CA: University of California: 7-16.

U.S. Department of Agriculture, Forest Service. 1988. Report of the Forest

Service: fiscal year 1987. Washington, DC: U.S. Department of Agriculture, Forest

Service. 188 p.

Ward, A.L.; Hansen, R.M. 1962. Pocket gopher control with the burrow-builder in

forest nurseries and plantations. Journal of Forestry. 60: 42-44.

Witt, S.; Contreras, G.; Ollieu, M.M. 1988. Effects of implementing EPA’s

endangered species program on National Forest System lands, In: Crabb, C.A.;

Marsh, R.E., eds. Proceedings, 13th vertebrate pest conference; 1988 March 1-3;

Monterey, CA. Davis, CA: University of California: 160-162.

194
Appendix 4:

Deer Fence

Contracts-Examples

195
196

Examples of specifications used for contracting the construction of nylon and woven

wire, game-tight fence, and specifications for contract purchasing nylon mesh fencing

material.

Exhibit 1. Sample contract from the Suislaw National Forest, Oregon.

AWARD

Deer Fence Contract

Award will be made on an all or none basis to one contractor. Bids offering less than

10 days for acceptance by the government from the date set for opening will be

considered nonresponsive and will be rejected.

CONTRACT PERIOD - DATE OF DELIVERY

The Government desires that delivery be made at the points specified within 45

calendar days after notice of award.

Bidder shall insert in the appropriate blank below a definite number of days within

which delivery will be made. If the bidder does not insert a delivery time, the bid shall

be deemed to offer delivery in accordance with the Government’s desired delivery

date above. Although time of delivery will not be a factor in determining award, any

bid offering a delivery time which exceeds 60 days after notice of award will not be

considered for award on the basis that the time for delivery offered is unreasonable.

BIDDER PROPOSED DELIVERY days after notice of award.

DELIVERY POINTS

Delivery shall be made f.o.b. to the following points in the quantities shown:

Delivery Point Yards Sections

1. District Ranger, Alsea Ranger

District, Alsea, OR 97324 4180 19

2. District Ranger, Waldport Ranger

District, Waldport, OR 97394 2640 12

TOTAL 6820 31

BID SCHEDULE

Item Per

No. Section Amount

1. Nylon Fence Netting to be in

complete accordance with the

terms and specifications of

this bid invitation. 31 Sections

(6820 linear yards)’

$

Signature of Bidder
Exhibit 1, Continued

SPECIFICATIONS FOR PURCHASING NYLON FENCING MATERIAL

1. Netting

1.1 The twine fiber shall be continuous filament bonded nylon. The twine shall have

a tensile strengh of at least 115 pounds.

1.2 Netting Twine Size: 15 thread.

1.3 Mesh size will be 6 inch, stretched measure.

1.4 Width or depth: 8 feet, hung measure.

1.5 Selvage: single.

1.6 Weaving: the netting shall be woven with single knots.

1.7 Treatment: the netting shall be untreated.

2. Hanging

2.1 The netting shall be hung square or diagonally square, and it shall be full-out.

2.2 The netting shall be hung with 18 thread nylon twine with a tensile strength of

150 pounds.

2.3 The top line shall be five-sixteenth (5/16) inch polypropylene rope with a tensile

strength of 2,100 pounds.

2.4 The bottom line shall be one-quarter (1/4) inch polypropylene rope with a tensile

strength of 1,200 pounds.

2.5 The net shall be hung, top and bottom, at every second mesh.

2.6 The top and bottom lines shall extend two (2) feet beyond the netting ends to

permit tying.

3. Section Length.

3.1 Each of the 31 sections of net shall be 220 yards in length, hung measure.

Each section shall be packed separately and in such a manner that it may be

removed from the package without tangling.

Buy American Act

Particular attention is directed to clause 4 of the General Provisions (reverse of page

one).

197
Exhibit 2. Sample contract from the Deschutes National Forest, Oregon.

SPECIFICATIONS FRO SKELETON CAVE AND CAMP TWO FENCE CONSTRUCTION

SCOPE

Vendor to furnish all supervision, labor, tools, transportation, equipment, materials

and supplies listed herein, to construct two fences in accordance with these

specifications and attachments.

CLEARING

The right-of-way will be cleared to a width of sixteen (16) feet. The fence will be

constructed near the center line.

MATERIALS

The following materials, prefabricated for constructing the fence, have been stockpiled

near the construction area, and are government furnished:

1) Wooden posts

2) Steel post and clips

3) Wooden braces (contractor will cut to length)

4) Woven wire, 47-inch

5) Woven wire, 35-inch

6) Barbed wire

7) Telephone wire, #9 (for stays)

VENDOR-FURNISHED MATERIALS

The vendor shall furnish the following items:

2 ea. 12 ft. x 8 ft. metal gates, with all hangers, hinges, latches and supplies for

complete installation.

Staples, fence

Nails, 40d

Wire for guy wire

Scab lumber for protection of trees used as posts

All other required material and supplies not listed as government furnished

Posts - Spacing of posts shall not exceed 1 rod (16-1/2 feet).

Wooden posts shall be set plumb and to a depth of not less than 30 inches into the

ground. Material shall be firmly tamped around posts.

Posts in a straight line of fence shall have a minimum of 4 inches protruding above

the top strand of wire.

Live trees over 6 inches in diameter at breast height may be used in place of posts,

providing they are located not more than 1 foot out of line with the adjacent fence.

Before fastening wire to trees, a scab at least 2 inches thick and 9 feet long shall be

nailed securely to the tree. Staples shall be driven into scabs instead of trees.

198
Exhibit 2, Continued

Wooden Corner Posts - Live trees 12 inches in diameter at breast height will be used

for corners when available. Corner trees shall be scabbed in the same manner as

post trees. Wooden corner posts shall be set not less than 36 inches into the ground.

Excavated material shall be firmly tamped around the post.

Corner posts shall have a minimum of 4 inches protruding above the top of any wire,

anchor wire, or brace.

Anchor Posts - Corner posts shall be anchored as shown in Figure 1. The anchor

post shall be located a distance from the corner post that is equal to the height of the

corner post protruding out of the ground. (For example, if the corner post protrudes 9

feet out of the ground, the anchor post will be 9 feet from the corner post.)

The anchor post shall be the same diameter as the other fence posts and shall be

set at the same depth as the corner post. It shall be placed at a point that will split

the interior angle created by the two lines of the fence.

The anchor post shall protrude 4 inches above the top of the anchor wire and shall

not protrude more than 24 inches above ground level.

The anchor wire shall be of the wire furnished for this purpose. The contractor shall

make two loops around the anchor post and the top of the main fence post, twisting

the wire in the center to tighten. The ends of the wire shall be wrapped around the

anchor post and stapled securely.

Steel Posts - Steel post shall be driven into the ground so that the top of the anchor

wing will be not less than 6 inches below ground level.

The top of the steel post shall protrude at least 4 inches above the top strand of wire.

The posts shall be set plumb and shall be firmly embedded into the ground.

Clips shall be used to fasten the wire to the post. The clips shall be attached to the

post at the holding points, a maximum of 8 inches apart.

The posts may be driven with a hollow pipe driver. The posts shall be driven in a

manner that does not bend the posts or the anchor wings.

Posts, General - Every fifth post shall be wood. Where rock is encountered and it is

not feasible to use a steel post, an excavation shall be made and a wooden post

used, set as prescribed for wooden posts.

Gate Posts - Gate posts shall be set in the ground a minimum of 48 inches. The post

above the ground shall be at least 10’ - 0”, and protrude above the top of the gate 6

inches. Anchor posts for gates shall be set as described in that section and shall be

set at right angles to the line of the gate when closed. Anchor posts will only be

placed on the outside of the fence.

Gates - Two gates will be installed at points shown on the attached map.

Contractor may furnish aluminum of “lifetime” or equal quality, or may prefabricate

the gates by using 1-1/4” galvanized pipe with cross bracing and cover one side with

woven wire.

If the contractor elects to prefabricate the gates, he must obtain advance approval of

the design by the Forest Service

199
Exhibit 2, Continued

Bracing - All gates will be braced as shown in Figure 4. All horizontal and diagonal

brace poles will be notched into posts and spiked with two 40d nails on each end.

Any split braces will be replaced.

All corner bracing will be installed as shown in Figure 1. Where trees are used for

corners as specified, no bracing will be needed. All horizontal and diagonal brace

poles will be notched into posts and spiked with two 40d nails on each end. Any split

braces will be replaced.

Stapling - All horizontal wires shall be stapled firmly to the scab on every tree used

as a corner and to every corner post.

In other posts, the staples shall be driven in a manner that will provide some play

when undue stress is placed upon the wire. The staples should be placed at an

angle over the wire, so they will not split the post when driven. See Figure 3 for

spacing of staples.

Wire Arrangement - The wire shall be placed as shown on Figure 2, with the 47-inch

woven wire placed on the bottom, 35-inch wire above it, and two strands of barbed

wire spaced as shown on top.

After all 35-inch wire has been used, two rows of 47-inch wire will be used. Where

two rows of 47-inch wire have been used, the two strands of barbed wire will not be

used.

The two sections of woven wire shall be clamped together between posts with four

evenly spaced hog rings.

Stays shall be made from the No. 9 telephone wire supplied. These shall be placed

at third points between posts (two in each space between posts.) The stay wire shall

be wound around the top strand of barbed wire, looped once around the lower barbed

wire strand, and wound around the top strand of woven wire. Stays shall be tight and

straight in line. The strands of horizontal wire shall not be pulled out of line.

The woven wire shall be stretched tight, with no sag. Stretching shall be done with a

bar clamp or similar device. The wires shall not be kinked or otherwise damaged

during installation.

The barbed wire shall be stretched tightly with no sag. Any method of stretching that

does not kink the wire or damage the barbs will be acceptable.

Attachments

Vicinity map; Skeleton Cave and Camp Two Enclosures

Schematic Drawings

Skeleton Cave Enclosure

Camp Two Enclosure

Figures 1 and 2: corner bracing and tangent bracing

Figures 3 and 4: staples, height and gate bracing

200
Exhibit 2, Continued

VICINITY MAP

Skeleton Cave - Camp #2 Exclosures

Deschutes National Forest

Fort Rock Ranger District

Vicinity Map

201
Exhibit 2, Continued

Schematic Drawing of the

Skeleton Cave Enclosure

Schematic of the Skeleton Cave enclosure.

202
Exhibit 2, Continued

Schematic Drawing

of the

Camp Two Enclosure

All corners are located at

trees. A 12 ft. gate will be

required at one of the

corners and will require a

gate post.

Schematic of the Camp Two enclosure.

203


Exhibit 3. Specifications for installing woven wire fencing.

SPECIFICATIONS

1 Clearing a Trail for the Fence.

a. The fence location has been plainly marked with blue plastic flagging. This

flagging shall serve as the centerline of the trail to be constructed.

b. The trail shall be cleared of all logs, limbs, brush, and debris to a minimum

width of 4 feet, and all overhanging limbs, brush, vegetation and debris to a

height of 10 feet over the cleared trail.

c. Snags or trees leaning over the cleared trail shall be felled before fence

installation to prevent damage at a later date. These shall be designated by

the COR.

d. All debris, logs, limbs, and brush shall be discarded to the side of the trail

away from the unit being fenced.

2. Posts.

a. Posts will be installed at 12- to 20-foot intervals, as specified by the COR.

b. The posts shall be installed vertically and set 2 to 2-1/4 feet in the ground.

Leveling the posts vertically will not be required. The posts should appear

vertical.

c. All corner post shall be braced by the use of #9 wire and stakes or stumps

(See Figure 2). Generally, one wire and stake per post will be sufficient;

however, some posts may require two wires and stakes to stabilize the post.

Line posts may require a brace, if the direction of the fence changes enough

to place tension on the post.

d. Posts will be installed with the studded side facing out or away from the

unit being fenced.

3. Fence

a. The fence must be constructed in such a manner that there are no openings

large enough for a deer to pass through. The connections of one section of net

with the next must be made carefully, and enough anchor pins must be used

to keep the netting close to the ground.

b. Each section of net will be packed separately and in such a manner that

the contractor may remove the net from the package without tangling. The

COR will demonstrate how to unpack the net. Each section is 8 feet wide

and 220 yards long.

c. The net shall be hung from top by a single clamp, and the clamp will be

crimped with pliers to prevent vertical and horizontal slippage (Figure 2).

d. The net shall be fastened to the post at ground level by a single clamp, and

the clamp will be crimped to prevent vertical and horizontal slippage (Figure 4).

e. The net shall be anchored to the ground with a minimum of three anchor

pins, and more if unevenness of the ground requires it (Figure 4).

206
Exhibit 3, Continued

f. Each section shall be completed before connecting and fastening the next

section, Sag in the net between posts shall not be less than 4 or more than

6 inches after the section is completed. Sag may be taken up at each post.

g. The net sections shall be connected by tying the rope ends in a square

knot, or by laying the ends side by side and crimping two or three hog rings

around them. Vertically, the nets shall be attached with crimped hog rings

every 6 inches from the ground to the top. The sections must be connected

at posts.

h. Trees may be utilized for posts, if they are available. The COR shall

designate trees to be used, after the trail has been constructed.

i. Some splicing of netting will be required in areas where the fence crosses

steep canyons. The COR will give additional advice on splicing when needed.“”

The following attachments form a part of this quotation and any resulting contract:

1. SF-19, General Provisions (except Clause 10a, which is replaced by the

Contract Work Hours Standards Act).

2. AD-269, Contract Work Hours Standards Act.

3. Federal, State and Local Taxes.

4. Vicinity Map.

5. Project Map (Figure 1).

6. Fence Building: Figures 1 through 6, and a diagram of a post-driving tool.

U.S. Forest Service-Project Map (10 1/4” to 8 1/4”)

207
Exhibit 3, Continued

Type of Project Deer Fencing. Nylon Quote No. 66-36 Horn Creek #1 Unit C

Bid Unit

Project Layout By J. Strickfaden Item No. No. 

Date Oct. 11. 1985 Scale: 4” = 1 mile T. 4S. R. 10W Sec. 4

1. Project Area 5. (DEER FENCE INSTALLATION)

marked by Forest Service

2. Unit Boundary 6. Completed Unit:

3. - area shown 7. Dirt Spur Road

within legend

4. Do not - strip 8. Gravel Road

- wide along - _

edge of unit.

Figure 1

208
Exhibit 3, Continued

Figure 2 - Typical section (post).

209
Exhibit 3, Continued

nside of fencewithin project area

Outside of fence

Anchor post

Figure 3 - Installation of anchor post.

210
Exhibit 3, Continued

Figure 4 - Securing wire at fence corner.

211
Exhibit 3, Continued

Hebo Post Pounder

for 10’ steel posts

Approx. 35 Ibs.

Main pipe is 3 inches, outside-diameter. Handles are of 1 inch, inside-diameter pipe.

Plug in top is 1/4-inch plate welded into pipe. Lead can be added to plug, to lessen

jar on impact.

The post pounder is best operated by two people; one to steady the pounder while

the other provides the up and down motion.

% in. rodwelded to

pipe

3 in. wide collar

cut from 3 in.

dia. pipe and

expanded

to fit.

Slot in pipe

is 13/, in. wide.

Sliding collar

(ACTUAL SIZE)

1 = = = : -2 = = z =

1

4

10 in.

L

t

16 in.

I

I7 in.

ltl

72 in. 1 21 in.

L

t2 irk+

Slot l-3/4 in. w. --+

Pipe 3 in. dia. +

Figure 5 - Hebo post pounder.

212
Exhibit 3, Continued

fence fence

Q ft rfnnr

24 in. between

Treated wood post

Figure 6 - Device to permit deer to escape from within fenced enclosure.

213
APPENDIX 5:

Gopher Baiting Probes and

Forest-land Burrow Builder

214
Gopher Baiting Probes There are at least four acceptable types of gopher probes, all of which can be

constructed easily in Forest or District shops (Crouch 1933)‘.

For limited use in light sandy soil, or any soil that is not too hard, a satisfactory

probe can be made of a broom, fork, or shovel handle, as shown in A and B. One

end should be bluntly pointed, and a foot rest may be attached to aid in probing.

For use in hard soil, an iron rod may be inserted in one end, as illustrated in A to

be used as a “seeker,” the handle being bluntly pointed for enlarging the opening

through which the bait is to be placed.

For extensive use in relatively soft soil, a durableprobe may be made of 3/4-inch

galvanized pipe: one piece 30 inches long and one piece 14 inches long. The

30-inch piece is threaded at both ends and the other pieces at one end only. A

piece of 1/2-inch round iron about 2 inches long is welded into the unthreaded end

of the 14-inch pipe and bluntly pointed. The pieces are then arranged and fitted

together with two 3/4-inch T-joints, as shown in C.

For use in hard soil, the probe may be made of the following materials:

1 piece of 1/2-inch galvanized pipe, 34 inches long

1 piece of 1/2-inch galvanized pipe, 5 inches long

1 1/2-inch galvanized T-joint

1 piece of 1/2-inch round iron, 2 inches long

1 piece of highly tempered steel, 3/8-inch in diameter

and 28 inches long

1 3/8-inch set screw, 1 inch long

1 3/8-inch nut

1 reducer, 1/2-inch to 3/8-inch

The two pieces of pipe are each threaded at one end. The piece of round iron is

welded into the unthreaded end of the 34-inch pipe and bluntly pointed. A 3/8-inch

hole is bored in the T-joint, and the 3/8-inch nut is brazed over this hole to

accommodate the set screw. The piece of highly tempered steel is sharply pointed

on one or both ends and held in place by the set screw. The pointed end of a

hayrake tooth cut 28 inches long would serve well for this piece. These materials

are then assembled as shown in D. The runway is located with the sharp end of

the probe, and the blunt end of the probe is used to enlarge the hole to admit the

poisoned bait.

1Crouch, W.E. 1933. Pocket gopher control. Farmers Bull.

1709. Washington, DC: US. Department of Agriculture,

Bureau of Biological Survey. 21 p.

275
A

3/8 in. steel rod Broom handle

in. Shovel handle

Foot rest

C

Round

end

“solid

iron”

Foot rest

2 in.

Round

end

3

/8 in. nut brazed to T-joint “solid

iron”

Gopher Bating Probes

216
Gopher Baiting Probes

41 in.

Plunger handle

Probe handle

with locking devic

Bait container (1 quart)

Metering valve handle

Plunger tip

Leppert Bait Probe

The Heavy-Duty Bait Applicator is designed to deposit a metered amount of bait

into pocket gopher burrows, with safeguards for both the operator and the

nontarget species. Any spillage or contact with the bait by the operator is

eliminated by using preloaded bait containers, and by the addition of a locking

device.

(1) Plunger handle with locking device

(2) Probe handle

(3) Bait container (1 quart)

(4) Metering valve handle

(5) Plunger tip

Operation Instructions

Step #l Attach the bait container. Hold the applicator upside down and screw the

container (3) into place.

Step #2 Turn the handle (4) one complete revolution. This places about 5 grams of

bait into the lower tube above the plunger tip (5).

Step #3 Locate the main runway of the gopher’s burrow system by probing 6-12

inches from the horseshoe-shaped mounds.

Step #4 When the runway is located, pull the applicator up so that the plunger tip

(5) is in the center of the runway; unlock and quickly depress the plunger

handle to let the bait fall into the runway. (It may be necessary to repeat

this step, depending upon soil moisture condition.)

Step #5 Extract the bait applicator from the burrow carefully, so that soil does not

cover the bait.

217
After each day of use, remove the container of bait by reversing step #l, replace

its cap and store both the container and applicator in a safe place. Caution should

always be used when handling pocket gopher bait.

Manufacturer: Leppert Machine and Welding

5635 South Sixth Street

Klamath Fa!ls, Oregon 97601

Telephone: (503) 884-9131

Approximate Price: $75.00 FOB Klamath Falls, for one applicator and five bait

containers; $1.OO for each additional bait container.

218
I 0 -A

“GOPHER GETTER JR”

A new inexpensive cartridge loaded unit which dispenses

poison bait automatically underground in pocket gophers

natural runway, out of reach of harmless birds and pets.

Ill STEP 1

To pomon pocket gophers. the natural ran.

way musl be located by

orobino about 12’10 18” irk 6s mound on the

side 01 Ihe horreshoeshaped depresstoe.

STEP 2

When rannay is lound.

ERSS red button on too

d the heedle lettmg tha

inside valve shaft teleSEW*, pull anit out of

Ihe ground. holding

down the red button.

I

The bait outomaticelly

drops into the gopher

rue r. ELSTON Co., Inc.

915 East 79th Street

Mwweowlis. Mtnnesota 55420

Elston Bait Probe

219
\ Upper link

Upper hitch poi

3 point hitch mast

Planting

attachment

Lower hitch points

Bait drop tube (3 point hitch)

Forest-land Burrow Builder

The Missoula Equipment Development and Testing Center (U.S. Department of

Agriculture, Forest Service) and the U.S. Fish and Wildlife Service developed a

heavy duty, gopher-burrow-building and baiting machine. This equipment

constructs and automatically baits artificial burrows. It is capable of operating

under conditions that prohibit use of other commercially available burrow builders,

In addition to its rugged construction, the machine is designed to lift out of the

ground when heavy obstructions are encountered.

220
Machine baiting functions are relatively simple. The torpedo moves through the

ground, wedging and shaping a round burrow approximately 2- inches in diameter.

The top of the burrow is immediately closed by packing wheels that are located

above the rear of the torpedo. The packing wheels also control torpedo depth and

meter the bait.

The baiting mechanism is a Dempster planter. When activated, it feeds teaspoonful

amounts of bait into a bait-drop tube, which leads directly to the bottom of the new

burrow. The Dempster planter is calibrated to drop bait at approximately 5-foot

intervals. About 450 bait drops are made per acre. With a rhoplex-treated oat bait,

this amounts to about 1 pound per acre.

Construction plans are available upon request from the Missoula ED&T Center.

Fabrication costs in 1978 were about $700-$800.

Continued machine use in abrasive soils will wear away the leading edge of the

shank and torpedo. Under normal use these parts should be rebuilt annually.

Eutectic Cromcarb 6006 should be sprayed on the worn surfaces, using a Eutalloy

Model B torch. If this torch is not available locally, the hard surfacing material

should be put on with an arc welder and ground smooth. Grinding is an important

step, because rough or irregular surfaces on the torpedo or shank will interfere

with their operation.

A major advantage of the burrow builder is that it provides a means for one

person to treat large areas rapidly. Acres treated per hour, at various tractor

speeds, when burrows are spaced 20 feet apart are as follows:

Tractor speed

(mph)

Area treated

per hour

(acres)

1.0 2.4

1.5 3.6

2.0 4.8

2.5 6.1

3.0 7.3

3.5 8.5 

The Region 4 (USDA Forest Service, Intermountain Region) vertical-lift hitch is

recommended for use with the Burrow Builder, because it also can be used for

mounting other common forest land equipment such as the Holt Plow and Rocky

Mountain Tree Planter. The Burrow Builder can be adapted quickly to fit category I

and II three-point and Holt Timber Hitches. All of these hitches will perform

satisfactorily with proper adjustment.

The Forest-land Burrow Builder was designed to operate under the wide range of

site conditions likely to be encountered on forest and range lands. Many acres can

be treated rapidly with a minimum of manpower. However, there are several

factors that control the effectiveness of machine operation, and it is important to

recognize these limitations.

221
Operational Limits

The following paragraphs describe acceptable and unacceptable operating

conditions:

Acceptable Operating Conditions

Slope-The best results are obtained on flat or gentle topography, but slopes up

to 20 percent can be treated effectively. Steeper slopes may be machine-baited,

provided they have first been terraced. Tree-row spacing on terraced strips must

be adjusted to allow a tractor to move between planted rows.

Obstructions-The burrow builder will perform satisfactorily through moderate

amounts of subsurface material such as rocks or large roots. It will usually

produce satisfactory gopher control, if 50 percent or more of the burrows are

properly formed, baited, and evenly distributed in the treated area.

The ground surface should be reasonably free of l-inch or larger limbs and dense

brush. Removal of surface obstructions to allow burrow-builder use is often

possible, if it is included in the initial project planning. For example, slash on

timber sale areas may be windrowed or bunched to provide an unobstructed travel

lane, with proper spacing for gopher control. Brushfield site-preparation plans can

also provide for clearings wide enough to allow machine travel between planted

tree rows.

Soil texture-Burrow construction is possible in a wide range of soil textures,

although fine-textured soils are most suitable for burrow construction.

Satisfactory burrows can be built in sandy or coarse pumice soils, provided other

site conditions are favorable.

Soil moisture-Soils should contain enough moisture to make them moderately

cohesive. This permits them to hold the form created as the torpedo passes

through the soil. Soil moisture is usually adequate for burrow construction in spring

and fall.

Unacceptable Operating Conditions

Slope-Suitable burrows cannot be constructed on sparsely vegetated slopes

exceeding 20 percent, when the machine is operated on the contour. Increased

slope angle causes uneven packing wheel pressure, which in turn results in poor

burrow closures. Operation up and down slope is not recommended because of

the possibility of starting gully erosion.

Obstructions-Large amounts of rock, large spreading roots, or a hardpan will

seriously interfere with burrow construction, because the machine will continuously

be forced out of the ground. Surface obstructions, such as logs, large limbs, large

rocks, or dense brush, interfere with machine operation. The machine should not

be used if obstructions prevent its proper operation at least half the time.

Soil texture-Soils containing large amounts of gravel often have insufficient fine

material to bind particles together. Burrows cannot be formed properly in this

situation.

222
Soil moisture-When soils become dry, they lose much of their cohesiveness.

The degree of this loss is largely dependent on the structure and texture of the

soil, and the number of fine roots in the profile. Sandy and other coarse soils,

such as pumice and sugar granite, represent the low end of the operational scale

and cannot be treated when dry; Clay soils often become difficult to work when

saturated with water. They become sticky and plug the bait-drop tube. Packed

snow or frozen soils also prohibit burrow-builder use.

Hitching Instructions

The Forest-land Burrow Builder is designed to operate with a Category I,

three-point, free-link hitch; a Category II, three-point hitch; the R-4, Vertical-lift

King Pin Hitch; and the Holt Timber Hitch (FSH 2409.26b). Instructions for

mounting the burrow builder to these hitches follow:

R-4 and Holt Vertical-life Hitches

1. Check hydraulic controls on the R-4 hitch to ensure that frame-tilt and lift

cylinders can be activated independently.

2. Make sure that hydraulic-lift cylinders on either hitch have a float valve. The

valve must be in float position, while the burrow builder is in the ground. This

allows the machine to seek the proper operating level and to rise out of the

ground when it hits a large obstruction.

3. Place vertical-lift hitch adapter on the burrow builder and hook to tractor. The

adapter may be adjusted vertically on the burrow builder to compensate for

different hitches and to allow the machine to operate at proper depth.

4. Attach safety chains. The burrow builder should not be lifted from the ground

before safety chains are attached, because the machine can swing freely to either

side and could cause a serious injury.

5. Adjust hitch so that the roller-frame assembly is vertical and the burrow builder

torpedo is horizontal when the machine is at operating depth. An exact vertical

alignment is necessary to permit proper burrow construction.

The R-4 hitch may be adjusted hydraulically to a vertical position, whereas shims

must be used with the Holt Hitch for vertical alignment.

Three-point Hitches

1. Check the hydraulic-hitch-lift system to ensure that it has a float valve, and that

the valve operates properly.

2. Place three-point hitch mast on burrow builder.

3. Hook burrow builder to the tractor. Do not attempt to lift machine until all three

points have been secured. When attaching the burrow builder to the category II

hitch, bushings will have to be placed on the hitch pins to increase their size.

4. Level the torpedo by adjusting the length of the upper hitch link. Additional

adjustment is possible by moving the mast to any one of three alternative

positions, or by turning it around.

223
The torpedo must be adjusted to a horizontal position with the ground surface,

when at working depth. This adjustment is critical, because the burrow will not be

satisfactory if the torpedo moves through the ground at an angle. A spirit level is

attached to the burrow builder to aid in this adjustment.

Burrow Builder Adjustments

The packing wheels control the working depth of the torpedo and are the only

point of adjustment of the burrow builder. They may be adjusted vertically, at

2-inch intervals, to obtain the desired burrow depth.

Tractor Selection

The choice of tractor for most field operations should be limited to one developing

30-drawbar horsepower or more. Either wheel or crawler tractors are suitable, but

the crawler type is more versatile in rough terrain. This is sometimes important in

traveling between areas on a project.

Tractor Operating Instructions

- Check soil moisture to be sure that it is sufficient to allow the soil to hold the

form created by the burrow builder. A simple soil-moisture test can be made by

squeezing a handful of soil taken from the depth at which the burrow is to be

constructed. If the soil forms a fairly tight ball, the burrow builder will operate

satisfactorily.

These procedures should be carried out before moving machinery into a project

area. This will prevent lost time in the event that soil moisture is unsuitable for

burrow construction.

- Determine the average depth of natural gopher burrows. This should be done by

opening and measuring the depth of several gopher systems in the area to be

treated.

- Adjust the packing wheels to give the proper burrow depth. It is difficult to

construct shallow burrows when vegetation is sparse. Under these conditions, it is

better to set the machine deep enough to allow good burrow formation.

- Fill the bait hopper with strychnine-Rhoplex treated oats, and secure the hopper

lid.

- Put the tractor in forward motion and slowly lower the burrow builder into the

ground.

- Put the lift valve into float position after the torpedo has reached operating depth.

- Construct 20 feet of burrow, then excavate sections to determine if the burrow is

properly formed at the selected depth, and if the bait is being metered at the rate

of about one teaspoonful every 5 feet. Also, check to see that the packing wheels

are completely closing the burrow.

- Make final burrow builder and hitch adjustments.

- Space burrows approximately 20 feet apart.

- Check frequently to ensure that the bait is flowing freely through the bait drop

tube.

224
- Never reverse the tractor when the burrow builder is in the ground, because soil

will be forced into the bait-drop tube.

- Do not exceed 3.5 mph operating speed, because burrows are often poorly

formed at higher speeds.

- Do not allow debris to accumulate on the lead edge of the burrow builder. These

accumulations will interfere with burrow construction. Most debris can be removed

by momentarily raising the machine while the tractor is in motion.

- Open artificial burrows periodically to make sure that they are being properly

formed. This is a very important step, especially when the burrow builder has just

been fitted to a new hitch or when starting to bait a new area.

- Grease the burrow builder once a day.

225
Glossary

226
Acceptance-Refers to the palatability of baits and toxicants.

Acute rodenticide-Toxic compound specifically formulated to kill rodents from a

single feeding.

Adult-Sexually mature; an animal that has contributed or is capable of contributing

new individuals to a population.

Age composition-The arrangement of age classes in a population, which describes

the relative size of the age classes; synonym, age structure.

Animal damage-In simplest terms, the result of any kind of animal activity interfering with resource management goals or objectives. (In the past, the emphasis had

been on animal activity that causes economic losses by reducing or delaying forest

yield.)

Animal unit-A measure for relating forage consumption by various animals (deer,

elk, sheep and so forth) to the forage resources, based on the equivalent of the

forage required by a mature cow of about 1,000 pounds.

Avicide-Generally, a lethal agent used to kill birds, but it also refers to other

materials or means of repelling birds.

Avoidance behavior-Behavior that postpones an aversive event and thus provides

escape from conditioned aversive stimuli.

Barking-The removal of bark from a stem. Bark may be stripped off as by a bear,

abraded by deer or elk polishing their antlers, or gnawed away by a porcupine.

Bioassay-Determination of the relative strength or specificity of a substance (a

contact repellent, for example) by comparing responses of test animals.

Biological control of vertebrates-An attempt to reduce the population density of a

pest species (that is, increase mortality, reduce natality, or cause a significant emigration), by increasing predation, manipulating the conditions of the habitat, introducing or stimulating epizootics, or applying antifertility agents.

Bole-The trunk or stem of a tree.

Broadcast burn-Intentional burning of debris on a designated unit of land by

allowing fire to spread over an entire area where debris has not been piled or

windrowed.

Browse--Palatable twigs, shoots, leaves, and buds of woody plants; a term often

used to describe a category of deer food.

Browsing-Feeding on woody vegetation by deer and elk that leaves a ragged,

splintered break where a shoot is removed. These animals cause this type of injury

because they lack upper incisors.

Budburst-Opening or flushing of vegetative buds, or beginning of shoot and foliage

growth.

Bud clipping-The removal of buds, as in grouse injuries to seedlings.

Buffer crops-Crops purposely planted to take the feeding pressure of wildlife and

other animals away from commercial crops.

227
Carrying capacity-The maximum density of a particular species of animal that can

be maintained in a given ecosystem on a sustained basis without degrading the

habitat; that is, the number of individuals that a habitat can maintain in a healthy

condition.

Chemical toxicant-Any chemical substance that when ingested, inhaled, or

absorbed or when applied to or injected into the body in relatively small amounts

may cause significant bodily malfunction, injury, or death to animals or humans by its

chemical action.

Chemosterilant-A chemical substance that causes sterilization or prevents effective

reproduction; although much researched for applications in animal damage

management, no chemosterilants are available for this purpose.

Clearcut method-A regeneration method that removes all trees over areas at least

2 acres or larger; generally with the objective of producing an even-aged forest by

either natural seeding or artificial regeneration.

Clearcutting-SilvicuItural system in which the entire standing crop of trees is

cleared at one time over a considerable area followed by regeneration efforts to

produce an even-aged forest. In practice, much unsalable material may be left

standing.

Clipping-Smooth, oblique cuts caused by rodents and rabbits feeding on woody

shoots. These animals possess prominent chisellike incisors and must tilt their heads

to the side to clip a stem.

Commensal rodents-Wild rats, especially of the genus Radius, mice (Mus),

and other wild rodents that live in association with humans, eat the same food

as humans, and adapt well to most human-made environments.

Contact repellent-A material applied as an external coating to the foliage and

stems of seedlings to repel animals.

Control-In wildlife management, the process of managing populations of a species

to accomplish an objective. The term usually is used in the sense of reducing

population numbers of a wildlife problem species to prevent or decrease the impact

of that species.

Cover-A general term used to describe vegetation and topography. Vegetative

cover is divided into three categories: the overstory of trees; the midstory, composed

mainly of large shrubs and small trees; and the understory that includes small

shrubs, grasses, and forbs.

Crash-The period of severe mortality following the peak of a cycle.

Cutting--Gnawing by rodents to sever a large stem (as when beavers fell trees, for

example). Cutting leaves multiple teeth marks on the cut surfaces.

Damage to buildings and grounds-Animal use that causes unacceptable health

hazards or excessive maintenance costs.

Debarking-See “barking.”

Direct seeding-Manual or mechanical sowing of tree seed on an area, either in

spots or broadcast.

228
Droppings-The fecal material (especially pellets) of animals are useful, supplemental field signs in the identification of animal-caused damage.

Edge-The place where plant communities meet or where successional stages or

vegetative conditions within plant communities come together.

Efficacy-Effectiveness as a rodenticide or other pesticide; ability of a product to

control the specified target species or to produce the specified action.

Endangered species-A species whose prospects for survival and reproduction are

in immediate jeopardy because of the loss of habitat, change in habitat,

overexploitation, predation, competition, use of pesticides, or disease.

Even aged-Term for a forest in which all trees are nearly the same age (+ 10

percent of their age at maturity). Trees in even-aged stands may be quite different in

size.

Even-age management-The application of a combination of actions that results in

the creation of stands in which trees of essentially the same age grow together.

Cutting methods producing even-aged stands include clearcut, shelterwood, or seed

tree.

Environment-All the organic and inorganic features that surround and affect a

particular organism or group of organisms; that is, both the biotic and physical factors

of the habitat.

Eradicate-Often used to imply the local extermination of a species (best stated as

“local eradication”).

Exterminate--Often used to imply the complete extinction of a species over a large

contiguous area such as an island or a continent. Not a good term for animal damage

management, because it may imply making a species extinct. Animal damage management attempts to limit damage, not to exterminate animal species.

Forage-All browse and herbaceous food available to birds or mammals.

Forage damage-Animal use that causes a downward trend in the abundance of

desirable plant species, or prevents maintenance of range in good condition.

Forb-Any herbaceous plant other than grasses or grasslike plants.

Forest pest-As defined by the Pacific Northwest Forest Pest Action Council, this

term included any animal that impairs the economic or aesthetic management of

forest resources. Some people prefer not to apply this term to big game and other

wildlife species because of the value accorded them by the public for sport hunting,

viewing, and as valued components of the forest ecosystem.

Formulation-Active ingredient packaged with various other materials produced by a

manufacturer of pesticides.

Fumigant-Substances producing toxic or suffocating gases.

Fur bearer-Any animal sought for its fur.

Girdling-The more or less continuous removal of bark around a stem as by a

porcupine or pocket gopher.

Group selection-A harvest-regeneration method used in uneven-age management.

Trees are removed from small areas ranging from 0.25 to 2 acres.

229
Habitat-The sum total of environmental conditions of a specific place occupied by a 

wildlife species or a population of such species. 

Habitat modification-Alteration of habitat primarily to limit damage to seedlings 

either by reducing suitability of habitat or by providing alternate (buffer) forage 

species for the problem species of wildlife. 

Herbicide-A chemical capable of killing plants or suppressing their growth and 

development. 

Home range-The area over which an individual animal habitually travels while 

engaged in its daily activities. 

Housekeeping-type pesticide-Any pesticide used for purposes of general maintenance of human and animal health and comfort in or around all structures, vehicles, or 

grounds associated with offices, laboratories, dwellings, and areas of concentrated 

human activity. Included are garages, warehouses, special equipment or facility 

buildings, vehicles, offices, houses, mobile homes, dormitories, bunkhouses, lawns, 

gardens, patios, kennels, stables, hutches, aviaries, ponds, noncommercial greenhouses, and garbage disposal or receiving sites. (Subslab treatment or deep-soil injection of insecticides for termite control, building fumigation, fire-hazard reduction 

around buildings with soil sterilants or other herbicides, pest control in food handling 

areas and storage buildings, or the use of pesticides that require applicator certification are not considered housekeeping-type pesticide uses.) 

Integrated control-A management system, within the area of associated environments and population dynamics of the wildlife problem species, that uses all suitable 

techniques and methods compatibly to maintain populations of problem species at 

levels below those causing economic injury. 

Irruption-An unusually high population density of either a cyclic or noncyclic 

species. 

Limiting factors-Any environmental factor limiting the distribution or the size of a 

population. 

Model-Formal description that represents a system or process. 

Multiple-dose bait-Poisonous bait that requires a sustained dosage over a period 

of time to produce death; for example, an anticoagulant. 

Natural control-The maintenance of a comparatively stable population density, with 

certain definable upper and lower limits over time, by the combined actions of abiotic 

and biotic (relating to life) elements of the environment. 

Natural regeneration-The renewal of a tree crop by natural seeding or sprouting. 

Nontarget species-Any species not the target of a control program. 

Palatability-How well an animal eats or “likes” a food. 

PesticideA substance or mixture of substances intended for repelling, destroying, 

or mitigating any vertebrate or invertebrate pest, or preventing the species from 

becoming a pest. 

Phytotoxic-Injurious and sometimes lethal to plants. 

230 
Plant association-The stable or unchanging plant community that occupies (or

eventually could occupy) a site after completion of the successional process.

Pole-A still-young tree from the time its lower branches begin to die until the time

when the rate of height-growth begins to slow down and crown expansion becomes

marked.

Prescribed burn-The controlled application of fire to wildland fuels in either their

natural or modified state to reduce the total amount of fuel and achieve other

designated objectives.

Rangeland damage-Grasslands and meadows are subject to three general types

of animal damage: plant destruction, soil compaction, and erosion.

Recreation area-In the context of pesticide labeling and use, it includes designated

areas of concentrated public use and sites developed for recreational use, such as

campgrounds, picnic areas, and other recreational facilities. This term does not

include primitive hunting, hiking, and fishing camps or undeveloped areas used only

occasionally by recreationists.

Reforestation-The natural or artificial reestablishment of a tree stand on forest land.

Regeneration-Young trees on an area that represents the early stages in the

renewal of a forest stand.

Regeneration (harvest) method-The type of cutting or harvest method used to

obtain a new stand (even-age management) or new trees (uneven-age management).

Regeneration survey-Any effort (particularly a planned and organized one) made

to assess the amount, distribution, and condition of regeneration present on a

specified area.

Release-The removal of plants by any of several means to free chosen trees from

immediate competition that is overtopping or closely surrounding them.

Repellent-A substance so obnoxious to animals as to deter them from attacking the

seed or plant to which it has been applied.

Residual vegetation-The decimated vegetation remaining after the main stand of

vegetation has been removed through harvest or other means.

Rodenticide-A pesticide applied as a bait, dust, or fumigant to destroy or repel

rodents and other animals, such as moles, rabbits, and hares.

Root clipping-The cutting or clipping of roots (as by pocket gophers, for example).

Rotation-The planned number of years between the formation or regeneration of a

crop or stand and its final cutting at a specified age of maturity.

Sapling-Loose term for a tree no longer a seedling but not yet a pole.

Scarification (of soil)-Disturbing the forest floor and topsoil in preparation for

natural regeneration, direct seeding, or planting.

Seed-tree harvest (cutting)--Removal of mature trees from an area in one cut,

leaving a small number of seed bearers or seed trees singly or in small groups.

231
Seed-tree method-A regeneration method that in one or more thinning or harvest

operations removes mature trees from an area and leaves a small number of highquality seed trees singly or in small groups. The primaryfunction of the residual trees

is to provide seed.

Seedling-In general, a young tree grown from seed, from germination to the sapling

stage.

Secondary poisoning-Poisoning that occurs when a chemical toxicant is retained

in a target animal in such a manner and quantity that its chemical action will cause

significant bodily malfunction, injury, illness, or death to nontarget animals or to

humans when the body part retaining that chemical is ingested.

Selection cutting-The cutting method in which individual trees or small groups are

removed annually or periodically from an uneven-aged forest.

Selective pesticide-A pesticide that, while killing the pest, spares much or most of

the other fauna, including beneficial species, either through differential toxic action or

through the manner in which the pesticide is used (formulation, dosage, timing, and

so forth).

Shelterwood harvest (cutting)-Regeneration cutting in a mature stand to establish

a new crop under the protection of the remaining stand. Trees are removed in

several stages to establish a new, even-aged crop under the protection of the older

stand.

Shelterwood method-A regeneration method that in one or more thinnings or

harvest operations removes mature trees from an area and leaves enough trees

to affect the site environment for establishment of seedlings. The function of the

residual trees is to modify the environment near the ground.

Silviculture-The art and science of managing forest stands to meet resource

objectives.

Silvicultural system-A process whereby forests are tended, harvested, and

replaced to result in production of crops of distinctive form. Systems are classified by

the method of felling that removes the mature crop with a view to regeneration.

Single-feeding (single-dose) bait-A toxic bait that produces death from one dose;

also called “acute toxic bait.”

Single-tree selection-A harvest-regeneration method used in uneven-age

management in which trees are removed either on the basis of their individual

maturity or to promote growth and maturity of neighboring trees. The objective is to

produce a stand with trees of all sizes and ages within areas less than 2 acres in

size.

Site preparation-preparing an area of land for regeneration establishment.

Soil compaction-Adverse changes in soil properties, which reduce water and air

capacity and movement, and root penetration capacity. Soil compaction can occur

when excessive numbers of big game or domestic livestock use areas of heavy

clay soils saturated with water. Areas damaged by compaction have a dimpled

appearance; animal hoofprints are discernible if the trampling is recent.

Soil damage-Animal use that leads to deterioration of the soil structure or to

accelerated erosion.

232
Stand-A plant community, particularly of trees, sufficiently uniform in species

composition, arrangement of age-classes, and condition to be a homogeneous and

distinguishable unit.

Stand establishment-Developing a tree crop to the stage at which the young trees

may be considered established (safe from normal adverse influences).

Stocking-With reference to forest stands, a more or less subjective indication of the

number of trees as compared with the desired number. More precisely, a measure of

the proportion of the area actually occupied by trees (as distinct from their stand

density), or the percentage of area stocked as compared with either maximum or

normal tree densities.

Stock type-A class of nursery stock produced by one or more of the basic

production methods over a particular length of time.

Succession-The gradual replacement of one plant community by another until

ecological stability is attained or until disturbance reinitiates the cycle.

Systemic repellent-A chemical applied to foliage, roots, or soil (at the root zone)

that is absorbed and translocated to all parts of the seedling (or tree) and that limits

the plant’s acceptance as food by animals.

Target species-Primary object of control; species against which efforts are directed

to control damage either by direct population reduction (trapping, baiting, or shooting)

or by using mechanical or chemical barriers to protect forest resources from

depredation by a particular species.

Thinning-A felling made in an immature stand primarily to accelerate diameter

growth; also, a selection made to improve the form of the trees that remain.

Threatened species-A species or subspecies that, although not presently

threatened with extinction, is in such small numbers throughout its range that it

may be endangered if its environment worsens. A “status undetermined species or

subspecies” is one that may be rare or endangered but for which more information

is needed (see “endangered species”).

Tolerance-An organisms’ ability to endure a pesticide or drug without ill effect; for

example, the state of its innate resistance or acquired immunity.

Toxicity-Poisonous quality, especially its degree or strength.

Translocation-The movement of dissolved substances through the vascular tissue

of a plant.

Trapnight-One trapnight equals one trap set for one night.

Tree damage-Animal use that delays regeneration, or that reduces the number of

desired trees below an acceptable stocking level.

2-0 seedlings-Seedlings aged 2 years in the seedbed and none in the transplant

bed.

Uneven aged-A term for a forest composed of intermingled trees that differ widely

in age and size.

233
Uneven-age management-The application of a combination of actions needed to

simultaneously maintain continuous, high-forest cover, recurring patches of

regeneration of desirable species, and the orderly growth and development of trees

through a range of diameters or age classes. Cutting methods that develop and

maintain uneven-aged stands include single-tree selection and group selection.

Vertebrate control objectives-To accomplish the desired effect with a maximum of

safety to humans and to forms of life useful or of neutral value to society, and that is

carried out with a minimum of disturbance to the biotic community. It is the alleviation

of the problem to a tolerable level, not the destruction of vertebrates.

Vertebrate pest-Any native or introduced, wild, or feral species of vertebrate animal

that is currently troublesome locally or over a wide area, to one or more persons, by

being a health hazard, a general nuisance, or by destroying food, fiber, or natural

resources. A pest to one person may, at the same time, have aesthetic or

recreational value to others.

Definitions included in this glossary are from the following sources:

Black, H.C., tech. ed. 1992. Silvicultural approaches to animal damage in Pacific

Northwest forests. Gen. Tech. Rep. PNW-GTR-287. Portland, OR: U.S.

Department of Agriculture, Forest Service, Pacific Northwest Research Station.

422 p.

Cummings, M.W. 1973. Study guide for agricultural pest control advisers on

vertebrate pests. Davis, CA: University of California, Division of Agricultural

Sciences.

Salmon, T.P.; Lickliter, R.E. 1984. Wildlife pest control around gardens and homes.

Oakland, CA: University of California, Division of Agriculture and Natural

Resources. 90 p.

Thomas, J.W., tech ed. 1979. Wildlife habitats in managed forests: the Blue

Mountains of Oregon and Washington. Agric. Handb. 553. Washington, DC: U.S.

Department of Agriculture, Forest Service. 512 p.

234
Metric Equivalents

235
When you know: Multiply by: To find:

Inches

Feet

Yards

Miles

Miles per hour

Chain (22 yards)

Acres

Square feet

Square mile

Gallon

Pound

Ton

Tons per acre

“Fahrenheit

2.54 Centimeters

0.31 Meters

0.91 Meters

1.61 Kilometers

1.61 Kilometers per hour

5.03 Meters

0.41 Hectares

0.09 Square meters

2.59 Square kilometers

3.79 Liters

0.45 Kilograms

0.91 Metric tons

2.24 Metric tons per hectare

5/9(oF-32) Celsius

236 ‘U.S. Government Printing office: 1994- 589-269/00018
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Black, Hugh C., tech. ed. 1994. Animal damage management handbook. Gen. Tech. 

Rep. PNW-GTR-332. Portland, OR: U.S. Department of Agriculture, Forest 

Service, Pacific Northwest Research Station. 236 p. 

This handbook treats animal damage mangement (ADM) in the West in relation to 

forest, range, and recreation resources; predator management is not addressed. It 

provides a comprehensive reference of safe, effectwe, and practrcal methods for 

managing animal damage on National Forest System lands. Supporting information is 

included in references after each chapter and in the appendices. 

Keywords: Animal damage management, integrated forest protection, wildlife problem 

species, damage identification. 

The Forest Service of the U.S. Department of 

Agriculture is dedicated to the principle of multiple 

use management of the Nation’s forest resources 

for sustained yields of wood, water, forage, wildlife, 

and recreation. Through forestry research, 

cooperation with the States and private forest 

owners, and management of the National Forests 

and National Grasslands, it strives-as directed by 

Congress-to provide increasingly greater service 

to a growing Nation. 

The United States Department of Agriculture (USDA) 

Forest Service is a diverse organization committed 

to equal opportunity in employment and program 

delivery. USDA prohibits discrimination on the 

basis of race, color, national origin, sex, relrgion, 

age, disability, political affiliation, and familial 

status. Persons believing that they have been 

discriminated against should contact the Secretary, 

U.S. Department of Agriculture, Washington, DC 20250, 

or call 202-720-7327 (voice), or 202-720-l 127 (TDD). 

Pacific Northwest Research Station 

333 S.W. First Avenue 

P.O. Box 3890 

Portland, Oregon 97208-3890