Forest

Service

United States

Department of

Agriculture

Pacific Northwest

Research Station

	

		

	



	




Robert G. Bromley and Thomas C. Rothe

General Technical Report

PNW-GTR-591

December 2003
Authors

Robert G. Bromley is a wildlife biologist and president of Whole Arctic Consulting, P.O. Box 1177,

Yellowknife, NT, Canada X1A 2N8; Thomas C. Rothe is Waterfowl Coordinator for the Alaska Department of Fish and Game, Division of Wildlife Conservation, 525 West 67th Avenue, Anchorage, AK,

USA 99518.

This report was prepared as a synthesis of biological information to assist agencies responsible for the

management of dusky Canada geese and their habitats. Under a 1998 Memorandum of Understanding,

the U.S. Fish and Wildlife Service, Alaska Department of Fish and Game, Washington Department of

Fish and Wildlife, Oregon Department of Fish and Wildlife, and U.S. Department of Agriculture, Forest

Service and Animal and Plant Health Inspection Service have agreed to cooperate to provide for the

protection, management, and maintenance of the dusky Canada goose population.
Conservation Assessment for the Dusky Canada

Goose (Branta canadensis occidentalis Baird)

Robert G. Bromley and Thomas C. Rothe

U.S. Department of Agriculture, Forest Service

Pacific Northwest Research Station

Portland, Oregon

General Technical Report PNW-GTR-591

December 2003

Published in cooperation with:

Pacific Flyway Council

U.S. Department of the Interior, Fish and Wildlife Service
Abstract

Bromley, Robert G.; Rothe, Thomas C. 2003. Conservation assessment for the dusky Canada

goose (Branta canadensis occidentalis Baird). Gen. Tech. Rep. PNW-GTR-591. Portland, OR:

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 79 p.

Dusky Canada geese compose one of the smallest populations of geese in North America and have exhibited a marked decline in the past 30 years. A comprehensive synthesis of past and current biological

information on the subspecies has been compiled to provide insights into the ecology and demography of

the population, as well as explore management efforts to promote long-term conservation. Duskys occupy a discrete range, which has allowed the development of focused, long-standing management programs. The 1964 Alaska earthquake set in motion significant ecological changes in wetlands, plant

communities, and the suite of predators on the dusky goose breeding grounds. A subsequent decline in

goose productivity has become the primary challenge to this population. Concurrently, habitats on the

western Washington and Oregon wintering grounds became more favorable for geese, but over 250,000

Canada geese of five other subspecies now occupy the region where formerly duskys were the majority.

In the 1960s, the harvest of dusky geese was recognized as a primary management concern and regulation was effectively implemented. At present, protection of diminished duskys amid 10 times as many

other Canada geese has created great complications for both management of hunting and attention to

increasing complaints of crop depredation by wintering flocks. Important information needs are suggested to improve population monitoring, evaluate specific causes of lost productivity, and assess the

direction and effects of succession of breeding ground habitats and conversion of winter habitats.

Keywords: Dusky Canada goose, Branta canadensis occidentalis, Alaska, Copper River Delta, nest

predation, Willamette Valley.
Preface

Canada geese (Branta canadensis) are among the most genetically diverse waterfowl species in North

America, with 11 distinct subspecies (Delacour 1954), including the dusky. Historical data and recent

studies of genetics suggest that the Canada geese of the north Pacific coast have expanded and segregated into several breeding populations only since the last glacial retreat, and that genetic composition

among Canada geese is quite dynamic in some areas. These characteristics challenge wildlife agencies

not only to answer the essential question of “What is a dusky Canada goose?” but also to develop a

regime of goose management that is both practical and conservative of biodiversity.

The dusky Canada goose population nests primarily on the Cooper River Delta of Alaska’s south-central

coast. The 1964 earthquake that occurred in this region triggered significant, long-term changes to habitats used by geese and a suite of avian and mammalian predators. Over the past 20 years, high predation

rates on eggs, goslings, and adult geese have resulted in significantly lower goose production. Agencies

responsible for the management of dusky Canada geese and their habitats recognize the diminished capacity for production in this population, as well as the special challenges involved in addressing their

long-term conservation needs. They share the goals of ensuring that the dusky Canada goose population

remains secure and that its public values are perpetuated. This conservation assessment is intended to

provide a thorough summary of historical and recent biological information about dusky geese as a resource for evaluating the current status of the population and planning future management and research

programs.

Waterfowl in the United States are managed cooperatively within four administrative flyways. The

dusky Canada goose is restricted in its distribution to the Pacific Flyway, and its management is coordinated through the Pacific Flyway Council (11 Western States) and cooperators. Key agencies include

the U.S. Department of the Interior Fish and Wildlife Service, Oregon Department of Fish and Wildlife,

Washington Department of Fish and Wildlife, Alaska Department of Fish and Game, and U.S. Department of Agriculture Forest Service. Long-term conservation goals, current issues, and recommended

management activities are embodied in the Pacific Flyway Management Plan for the Dusky Canada

Goose (Pacific Flyway Council 1997). Successful management of dusky Canada geese relies on extensive cooperation among state and federal wildlife agencies, agencies that manage public lands, and private landowners that support goose conservation.

The status of the dusky Canada goose and priority actions for its conservation are key elements in efforts to integrate management of aggregate wintering Canada goose stocks, public hunting, and goose

depredation on agricultural crops in the Pacific Northwest. Guidelines for addressing these more complex issues are found in the Northwest Oregon/Southwest Washington Canada Goose Agricultural Depredation Control Plan (Pacific Flyway Council 1998).
Summary

The dusky Canada goose (Branta Canadensis occidentalis Baird) is a medium-sized, dark-plumaged

subspecies that nests in the Copper River Delta (CRD) region of south-central Alaska, migrates along

the Pacific coast, and winters in southwestern Washington and western Oregon. Originally thought to

include geese breeding in coastal regions of southeast Alaska and northern British Columbia, it is now

recognized as being unique to a small part of the Gulf of Alaska. Subpopulations include those that nest

on the CRD, and those that nest on islands within Prince William Sound and on Middleton Island in the

Gulf of Alaska. This assessment focuses on the birds of the CRD; this subpopulation is the one experiencing decline and uncertainty, whereas island geese have been stable or increasing in number.

Over the past two decades, numbers of geese on the CRD have varied, but generally declined from

20,000 to 25,000 in the 1970s to between 12,000 and 15,000 in the 1990s. In response to the changing

status of this population, the Pacific Flyway Council and Study Committee, and agencies participating in

the management of duskys, cooperated in the development of this conservation assessment. The purposes are to (1) provide a comprehensive synthesis of current biological information on dusky Canada

geese complementary to the recently revised Pacific Flyway Management Plan for the Dusky Canada

Goose (Pacific Flyway Council 1997), (2) present an updated assessment of factors affecting the size

and stability of the population, and (3) serve as an aid to conservation planning and identification of information needs.

Dusky Canada geese winter in nutrient-rich, agricultural cropland where they store large fat reserves

important in meeting the energy needs of migration and reproduction. In early to mid April, they migrate

to the nesting grounds where they again feed vigorously to supplement fat reserves prior to and during

egg laying. Clutch size is four to six, and eggs are incubated for about 27 days. By early to late June,

most eggs hatch, and young gain flight by early to mid August, about the time breeding adults complete

their molt. Fall departure begins in September and is complete by late October. Little is known about

migration ecology, but geese arrive on the wintering grounds in October and November.

The CRD, the summer habitat of the geese, is a highly dynamic region continually influenced by tectonic,

glacial, riverine, and tidal forces. Duskys were highly productive during the 1950s through 1970s, and the

population was thought limited by hunting mortality, primarily on wintering grounds. There was minor loss

of eggs to inundation by high spring tides, and similarly low rates of loss of adults, eggs, and young to

predators. Indeed, numbers of geese responded quickly and positively to restrictive hunting regulations,

and to the establishment of refuges on their wintering grounds during the mid-1960s. In 1964, however,

an earthquake caused an uplift of the nesting grounds on the CRD, accelerating natural succession of

marsh habitat toward forested habitat. Although breeding success remained high during the first 12 to 15

years postearthquake, substantial changes in nesting and brood-rearing habitat began to occur. As soil

salts were leached away by high rainfall and lack of regular tidal inundation, the salt-tolerant plant community gave way to expansion of willows, alders, and sweet gale. More recently, spruce and cottonwoods have become well established in the old marsh habitat still used by nesting geese.

Associated with changes in the plant ecology on the delta were concomitant faunal changes. In particular, brown bears and coyotes occurred on nesting and brood-rearing areas in greater abundance than

previously and were much more active predators on the geese and their eggs. Nest success rates wavered, then plummeted to low levels (4 to 44 percent) where they have remained over the past decade.

As succession progressed, predator species, numbers, and effect on duskys varied. Current research on

predators of eggs, adults, and goslings indicates that bald eagles may be the most important predator on

the delta. Duskys responded to high rates of nest depredation by renesting, a phenomenon not documented previously. First nests often have relatively low success compared to nests initiated later in the

season, probably because alternative prey become abundant as the season progresses. Nevertheless,

average nest success of individual pairs remains low and is made worse by low gosling survival.
Beginning in the late 1930s and through the late 1940s, managers recognized that duskys wintered primarily in the Willamette Valley, Oregon, and in the lower Columbia River of Oregon and Washington.

Analysis of leg bands returned in the mid-1950s established that these geese were from the CRD, and

by the 1960s, most of the geese on the wintering grounds were enumerated as duskys. As conditions

changed in summer habitats, other events caused changing conditions on wintering grounds. Perhaps

because of protection provided to duskys, as well as favorable agricultural food resources, other subspecies of geese increased in both diversity and abundance on the wintering grounds of duskys. Starting in

the early 1970s, a noticeable increase in Taverner’s (B.c. taverni Delcour) and lesser Canada geese

(B.c. parvipes Cassin) was recorded. Since then, numbers of western Canada geese (B.c. moffitti

Aldrich) also have increased, and, in the 1990s, the majority of cackling Canada geese (B.c. minima

Ridgway) shifted their winter range from California to western Oregon. Small numbers of Vancouver

Canada geese (B.c. fulva Delacour) have always wintered there, but trends in their wintering number

remain unknown. Thus, where 25,000 geese, primarily duskys, once wintered, there are now over

250,000 birds of which only a small proportion are duskys.

In response to low productivity and high vulnerability to hunting mortality relative to other sympatric wintering geese, managers began to limit the harvest of duskys in the 1980s. Currently, Canada goose hunting is permitted in wintering areas only as long as the harvest includes less than an annual quota of 250

duskys. Consequently, survival rates of adult birds have increased dramatically. The population, however,

is now limited by factors associated with accelerated ecological succession on the breeding grounds,

primarily depredation of eggs, young, and adults. Thus, since the late 1970s, the population has declined

to about half its former peak abundance. Significant management efforts on the breeding grounds have

included experimentation with, and operational establishment and maintenance of, artificial nesting islands on the CRD. Duskys consistently have much higher nest success (averaging 59 percent) on the

structures than at natural sites (averaging 22 percent).

The size of the dusky population has been monitored on wintering grounds since 1947 and on breeding

grounds since 1978, but survey difficulties persist for both areas. On the wintering grounds, traditional

midwinter aerial surveys sufficed until other races of geese began wintering sympatrically with and in

greater numbers than duskys. Subsequently, aerial surveys were complemented with ground surveys in

the mid-1970s, and aerial photography was implemented in the 1980s to determine the proportions of

large dark geese in the midwinter population. Since 1995, a mark-resight procedure has been used to

yield an indirect population estimate. Ratios of duskys marked with colored neckbands to unmarked

duskys are determined from samples of geese observed during two resighting periods. A population

estimate is developed by expanding the total number of recorded marked individuals by a factor for the

unmarked proportion of the population. This method, however, assumes that all marked geese are

equally likely to be observed during resighting survey periods. Results of recent surveys suggest that the

detectability of marked geese and accuracy of the indirect estimates may vary by year; major weather

events in some years have thoroughly mixed duskys to produce unusually effective sampling. Monitoring

of the CRD subpopulation during winter has been even more challenging because these geese winter

with island geese from Prince William Sound and Middleton Island. The problem of observers not being

able to distinguish the groups is exacerbated to an unknown degree by other large dark birds such as

Vancouver Canada geese and immature urban geese from Anchorage mixing with duskys in Oregon and

Washington.
On the CRD, aerial surveys seem to have provided reliable trends in numbers of geese on nesting areas.

Experimental work has yielded widely differing and unpredictable air-to-ground correction factors, thus

preventing the derivation of total estimates from aerial survey indices. Rapidly increasing canopy closure

from accelerated shrub succession on the delta has further thwarted development of visibility correction factors. Despite these complexities, there is general agreement that the CRD population increased

in number until the late 1970s, then rapidly declined in the 1980s, and has remained low but relatively

stable through the 1990s. Efforts to increase the reliability of population estimates remain a priority for

managers.

In the short term, accelerated succession is expected to continue on the CRD, and productivity of geese

will likely remain low because of high levels of predator activity. New marsh habitat will slowly develop

on accreting upper tidal areas, but it will not likely affect productivity of the dusky goose population in

the near term. Artificial nest islands will continue to enhance gosling production, but the degree to which

this program improves gosling and adult survival and recruitment is a critical unknown. Therefore, adult

mortality remains a critical parameter warranting close monitoring of the population and cautious management of harvest.

Although there are no known examples of dispersal between CRD geese and island geese, it is likely

that some exchange between subpopulations occurs. In the context of a metapopulation, dispersal

between subpopulations likely will gain significance over time. The CRD is currently a sink for geese,

but it is possible that geese from Middleton Island and Prince William Sound will become a source for

duskys. Contributions of breeding birds dispersing from these areas to the CRD will either help the

CRD population persist over time until favorable habitat conditions are restored or will help to reestablish

duskys after salt-marsh conditions return. The enhancement of this possibility is seen as a management

opportunity.

In the long term, studies have indicated that the delta is characterized by cycles of uplift followed by

gradual subsidence that occur over intervals of 600 to 900 years. Thus, over the next hundreds of years,

gradual development of new marsh, coupled with subsidence of the old marsh, will eventually cause

reversion of much of the CRD to salt marsh once again. To benefit in the future, duskys must survive

as a viable population over the long term. Based on the examples of several other small populations of

geese that have persisted in coastal Alaska, and with the degree of management attention being directed

to duskys, there are reasons to be optimistic. Vigilant monitoring and innovative management will likely

be key as habitat evolves, predators change, and the influence of man is manifested in unpredictable

ways.

Important topics for research include taxonomic review of regional populations of breeding geese;

improvement of population estimates; detection and enhancement of dispersal between subpopulations;

evaluation of the potential effect of an aging population on their productivity; regular updating of information on important predators and their changing roles in the face of habitat change, with an eye toward

management opportunities; assessment of how habitat changes will influence nutritional aspects of

reproduction; and investigation of establishment of new coastal marsh, including development of methods

to predict rates of expansion.
Contents

1 Introduction

1 Taxonomic Status

1 Original Description

1 Recognition as Valid, Well-Defined Subspecies

2 Morphology

5 Genetic Analyses

9 Perspectives on Taxonomy for This Report

9 Population Delineation and Distribution

9 Breeding Range

12 Wintering Range

14 Migration

15 Significant Events in Recent History of Dusky Canada Geese

15 Alaska Earthquake 1964

19 Establishment of Refuges on Wintering Grounds

19 Wintering Ground Complex of Canada Goose Subspecies

20 Biology

20 Reproduction

30 Migration

31 Wintering

32 Food Habits

33 Habitat

36 Population Dynamics

36 Population Status

40 Population Trend

40 Productivity and Recruitment

41 Survival and Mortality

42 Limiting Factors

42 Predators and Depredation

50 Hunting Mortality
51 Breeding Habitat and Recruitment

52 Summary of Ecology and Ecosystem Dynamics With Regard to Foreseeable

Environmental Conditions

52 Ecology and Ecosystem Dynamics

54 Short-Term Outlook

54 Medium-Term Outlook—Implications of Source-Sink Metapopulation Dynamics

55 Long-Term Outlook

56 Knowledge Gaps and Information Needs—Relationship to Management

56 Taxonomy and Classification

57 Distribution

57 Breeding Population Estimates

57 Exchange Between Copper River Delta Geese and Island Geese

57 Population Age Structure

58 Depredation

58 Adult Mortality on Nesting Grounds

58 Why Is Use of Artificial Nesting Islands So Low?

58 Quality of Breeding Habitat Given Accelerated Plant Succession

59 New Marsh Development and Old Marsh Plant Succession

59 Winter Foraging Ecology

59 English Equivalents

59 Acknowledgments

60 References
1

Introduction

The dusky Canada goose (Branta canadensis

occidentalis Baird) is a distinctive race of

medium-size geese (about 3 kg) with dark brown

plumage that primarily nests on the Copper River

Delta (CRD), Alaska, migrates through southeastern coastal Alaska and coastal British Columbia, and winters primarily in southwestern

Washington and western Oregon. The population

has been intensively managed since the 1950s

(Pacific Flyway Council 1973, 1985, 1992). Despite management, the size of the population has

gone through considerable fluctuations over the

past three decades, with an overall decline since

the late 1970s. Events on both the breeding and

wintering grounds have affected the status of

duskys. In 1964, an earthquake caused the nesting

grounds of the geese to be uplifted an average of

2 m, initiating decades of dramatically accelerated plant and animal succession and physiographic change that is ongoing today. This

succession has resulted in significant habitat

changes, with associated effects on activities

and populations of goose predators and subsequent detrimental effects on productivity and

numbers of geese.

Beginning in the early 1970s and increasing to

the present, tens of thousands of Canada geese of

several other races began wintering sympatrically

with duskys. Only 25,000 Canada geese, the vast

majority being duskys, wintered in the Willamette

Valley of Oregon in 1973. Over 250,000 Canada

geese, less than 10 percent duskys, winter there

today. Harvest management and population estimation of duskys became more complex and

challenging in the face of this massive buildup

of geese, particularly given the duskys’ declining

productivity and relatively high vulnerability to

hunting.

In response to the changing status of this population, the Pacific Flyway Council and Study Committee and agencies participating in the management of duskys cooperated in the development of

this conservation assessment. The purposes are to

(1) provide a comprehensive synthesis of current

biological information on dusky Canada geese

complementary to the recently revised Pacific

Flyway Management Plan for the Dusky Canada

Goose (Pacific Flyway Council 1997), (2) present

an updated assessment of factors affecting the

size and stability of the population, and (3) serve

as an aid to conservation planning and identification of information needs.

Taxonomic Status

Original Description

The type specimen for dusky Canada geese

(Branta canadensis occidentalis Baird), originally Bernicla occidentalis, was collected near

Port Townsend, Washington, in 1857 and described by Baird (1858). The bird had upperparts

of dark wood brown, and the underparts were

very dark brown. He reported a total body length

of about 890 mm and a tarsus of 87.4 mm. Baird

(1858) reported the habitat (range) as the west

coast of North America.

Recognition as Valid, Well-Defined

Subspecies

All large, dark Canada geese (white-cheeked

geese) breeding on the Pacific Coast from Prince

William Sound (PWS) to northern California or

at least to Vancouver Island, British Columbia,

were originally placed in occidentalis (Aldrich

1946, AOU 1910), until Delacour (1951, 1954)

split Branta canadensis fulva off as a separate

subspecies. The Vancouver Canada goose (B. c.

fulva) is slightly larger and lighter-plumed than

the dusky (Johnson et al. 1979). Vernacular

names (dusky and Vancouver) follow Hansen

and Nelson (1964). The dusky is generally now

recognized as a valid subspecies (Aldrich 1946;

Bellrose 1986; Delacour 1951, 1954); however,

Dickinson (1953), Ogilvie (1978), and Palmer

(1976) suggest combining B. c. fulva with

occidentalis, and Sibley and Monroe (1990) did

not recognize dusky geese in their review of

world bird taxonomy.

Richard C. Banks, chief taxonomist with the U.S.

Fish and Wildlife Service (USFWS), in a 1992

memo to Chief, Office of Migratory Bird Management (Banks 1992), reported that the National

Museum of Natural History follows the American

Ornithologists’ Union checklist, 5th edition (AOU
79

Trainer, C.E. 1967. Appraisal of Canada goose nesting densities on the Copper River Delta, Alaska.

Unpublished report. 9 p. On file with: USDI Fish and Wildlife Service, 3000 Vintage Boulevard,

Suite 200, Juneau, AK 99801.

Trost, R.E.; Naughton, M.; Harb, L. 1995. Estimated number of dusky Canada geese, March 1995.

Unpublished report. 2 p. On file with: USDI Fish and Wildlife Service, 911 NE 11th Avenue,

Portland, OR 97232.

U.S. Department of the Interior, Fish and Wildlife Service. 1980. Objectives for managing the

Willamette Valley National Wildlife Refuges. Unpublished report. 70 p. On file with: USDI Fish

and Wildlife Service, Willamette Valley National Wildlife Refuge Complex, 26208 Finley Refuge

Road, Corvallis, OR 97333.

U.S. Department of the Interior, Fish and Wildlife Service. 1996. Migratory bird hunting;

final frameworks for late-season migratory bird hunting regulations: final rule. Federal Register.

61(188): 50666.

VanderPol, H. 1997. Personal communication to Dave Crowley, Alaska Department of Fish and

Game. Bird observer. 3389 Casorso Road #18, Kelowna, BC, Canada V1W 3J5.

Voight, D.R.; Earle, B.D. 1983. Avoidance of coyotes by red fox families. Journal of Wildlife

Management. 47: 852-857.

Welch, J.M. 1978. Translocation of dusky Canada geese from Copper River Delta, Alaska to Willapa

National Wildlife Refuge, Washington. Unpublished report. 5 p. On file with: USDI Fish and Wildlife Service, Willapa Bay National Wildlife Refuge Complex, 3888 SR 101, Ilwaco, WA 98624.

Wiens, J.A. 1996. Wildlife in patchy environments: metapopulations, mosaics, and management. In:

McCullough, D.R., ed. Metapopulations and wildlife conservation. Covelo, CA: Island Press: 53-84.

Witten, E. 1995. The role of a Sitka spruce (Picea sitchensis) population in plant community

succession following tectonic uplift of the Copper River Delta, Alaska. New Haven, CT: Yale

School of Forestry. M.S. thesis.

Woodcock, A.R. 1902. An annotated list of the birds of Oregon. Oregon Agricultural Experiment

Station Bulletin. 68: 1-119.

Wootton, J.T.; Bell, D.A. 1992. A metapopulation model of the peregrine falcon in California:

viability and management strategies. Ecological Applications. 2(3): 307-321.

Youkey, D. 1995. Memorandum to D. Logan, wildlife biologist, Cordova Ranger District. Preliminary

analysis of dusky Canada goose nest searches. 2 p. On file with: USDA Forest Service, P.O. Box

280, Cordova, AK 99574.

Youkey, D. 1998. Dusky Canada goose nest distribution and abundance on the Copper River Delta,

Alaska. Unpublished report. 8 p. On file with: USDA Forest Service, P.O. Box 280, Cordova, AK

99574.

Zeillemaker, C.F. 1973 (19 April). Letter to D.E. Timm, Waterfowl Coordinator, Alaska Department

of Fish and Game. 1 p. On file with: Alaska Department of Fish and Game, 525 West 67th Avenue,

Anchorage, AK 99518.

Zeillemaker, C.F. 1974 (21 April). Letter to D.E. Timm, Waterfowl Coordinator, Alaska Department

of Fish and Game. 1 p. On file with: Alaska Department of Fish and Game, 525 West 67th Avenue,

Anchorage, AK 99518.
2

1957), for subspecies classifications of Canada

geese. Banks recognizes the 10 subspecies listed

there, including B. c. occidentalis and fulva, plus

an 11th, Taverner’s (B. c. taverneri Delacour).

Although the dusky Canada goose was not included in the 6th edition of the checklist (AOU

1983), it is currently recognized and managed as

a distinct subspecies (Pacific Flyway Council

1997).

Morphology

Copper River Delta geese—The dusky Canada

goose is a medium-sized race with a body mass

of 2.7 to 3.9 kg during winter (Bromley 1981,

Chapman 1970). The subspecies is characterized

by dark plumage overall, with dark ventral feathers varying from rich brown (chestnut to near

chocolate) to medium charcoal gray (Bellrose

1986, Chapman 1970). Morphological measurements of CRD birds are summarized in table 1.

General consistency is apparent between studies,

although measurements were not combined for

analyses because of insufficient overlap in the set

of measurements taken in each study, and to

avoid the problems of potential biases between

measurers.

Island-nesting geese—Canada geese breeding

throughout PWS west of the CRD, and on

Middleton Island in the Gulf of Alaska (hereafter

referred to as island geese) are not well studied.

An unknown number of Canada geese breed in

PWS, nesting on islands and the forested mainland shore (Isleib and Kessel 1973), with known

concentrations on Green Island, Constantine Harbor of Hinchinbrook Island, and Middleton Island

(Isleib 1977, Kurhajec 1977, Nysewander and

Knudtson 1977). Thirteen island geese collected

in PWS by J. Reynolds of Alaska Department of

Fish and Game in 1970 and 1974 apparently were

intermediate in morphological characteristics

between duskys and Vancouvers (Isleib 1977),

although the four birds (one nesting pair, one

nesting female, and a nonbreeding female) collected in 1970 were identified by J. Aldrich on

the basis of morphological measurements as three

dusky females and one Vancouver male (Timm

1972b). Isleib (1977) also presented weight, culmen, and tail-length measurements of four island

geese collected by Ansel Johnson of the USFWS.

Presented by age class but not sex, culmen measurements were typical of the upper range of

duskys, weights were 300 to 1000 g greater

than averages for duskys, and tail feathers were

typical of Vancouvers (Chapman 1970, Ratti and

Robards 1977). Four adult female geese measured by Crowley et al. (1998) on Green Island

were slightly larger than CRD birds (table 2).

Middleton Island is situated in the Gulf of

Alaska, 150 km south-southwest of Cordova,

Alaska. Canada geese only recently became established on the island (reviewed in Campbell

1987), as observers did not detect resident, breeding geese there prior to 1981 (Gould and

Zabloudil 1981). Soon after they became established, Middleton Island geese gradually increased in the 1980s (Campbell 1987, Campbell

and Rothe 1990) and grew rapidly in the 1990s

(Campbell 1990a, Petrula et al. 2002). These

geese are indistinguishable in appearance from

CRD geese, and geese from both Middleton and

Green Islands have similar morphology to CRD

geese (table 2)(Crowley et al. 1998).

Egg measurements for island geese are also available for comparison (table 3). Although insufficient data are presented to allow statistical

comparisons, eggs from geese on Hawkins Island

(n = 23) were smaller than both duskys (Timm

1972b) and Vancouvers (J.G. King in Timm

1972b; also, see Lebeda 1980 for additional

Vancouver egg measurements that agree well

with King’s). Another sample (n = 26 eggs) from

Hinchinbrook Island (Kurhajec 1977), however,

appeared longer than Vancouver eggs but narrower than those of duskys. Eggs from Green and

Gravina Islands (Crowley and Petrula 1998) were

very similar to those of CRD geese.
3

Table 1—Morphological measurements of dusky Canada geese from the Copper River Delta, Alaska

Adults Juveniles

Males Females Males Females

1970 1979a 1970 1979a 1970 1970

Measurement n x sd x sd n x sd x sd n x sd n x sd

 – – – – – Millimeters – – – – – – – – – – Millimeters – – – – – Millimeters Millimeters

Culmen 214 46.5 2.7 46.3 2.4 199 44.4 2.1 43.5 2.4 368 46.9 2.2 350.0 44.6 2.2Bill width at nares 21.3 .8 20.0 .9Bill nail length 14.8 1.0 13.8 .9Diagonal tarsus 80 92.3 6.1 88.6 3.5 61 85.9 4.1 81.3 3.0 47 91.2 4.2 47.0 91.2 4.2Total tarsus 106.2 3.9 97.3 3.4Midtoe + nail 79 88.0 3.8 61 83.1 3.4 48 86.2 4.0 52.0 81.4 3.2Midtoe 80.8 7.4 74.6 6.5Flattened wing 79 479.0 12.6 61 450.0 15.1 48 462.0 13.8 52.0 440.0 12.9Tail length 79 143.5 6.5 60 137.4 6.8 48 129.7 7.5 47.0 124.4 6.6

a Johnson et al. (1979) measured a total of 261 adult dusky Canada geese, but did not report the sample size for each sex.

Source: Chapman 1970 and Johnson et al. 1979.
4

Table 2—Morphological measurements of Canada geese from Green and Middleton Islands,

Alaska

Green Island Middleton Island

Adult Females (n=4) Adult Females (n=12) Adult Males (n=18)

Measurement Mean Std. dev. Mean Std. dev. Mean Std. dev.

 Millimeters 

Culmen 45.0 1.24 43.2 1.85 46.0 1.86

Front nares 22.8 .66 24.3 .56 24.9 1.07

Bill nail length 14.3 .45 14.7 .91 15.5 .82

Bill nail width 11.9 .64 11.7 1.02 12.9 1.05

Bill width at base 23.7 .82 23.7 1.62 25.3 .96

Bill width at nares 21.1 .66 20.9 .77 22.1 1.12

Bill width at nail 17.8 .64 18.1 .53 18.9 .41

Total tarsus 98.6 1.30 98.2 3.69 104.3 4.12

Diagonal tarsus 84.9 1.56 85.1 5.03 89.5 4.05

Middle toe with nail 66.4 3.09 70.9 5.30 76.1 5.16

Wing chord 433.0 6.16 NA NA NA NA

Source: Crowley et al. 1998.

Table 3—Egg measurements of dusky Canada geese and closely related populations

Length Width

Population Location n Mean Min. Max. Mean Min. Max.

– – – – – – – – – – – Millimeters – – – – – – – – – – –

Duskya Copper River Delta 296 81.7 75.5 90.0 55.8 51.1 60.8

Islandb Hinchinbrook Island 23 79.7 77.7 83.8 55.1 53.7 56.5

Islandc Hinchinbrook Island 26 84.6 80.0 91.1 53.2 52.0 58.2

Islandd Gravina and Green Islands 25 82.3 76.3 88.2 54.0 49.9 57.7

Vancouvere Admiralty Island 36 86.1 81.5 94.0 56.4 51.5 61.8

Vancouverf Juneau 14 82.7 78.3 87.6 59.5 58.3 61.6

a

 Timm 1972b

b

 Reynolds in Timm 1972b

c Kurhajec 1977

d Crowley et al. 1998

e Lebeda 1980

f

 J.G. King in Timm 1972b
5

Comparisons with closely related subspecies—

Morphological profiles of six Alaska subspecies

of Canada geese, including duskys, are fairly

distinct (Johnson et al. 1979); however, separations between duskys, lesser Canada geese (B. c.

parvipes Cassin), and Vancouver Canada geese

were not considered adequate. By using discriminant function analyses of culmen, tarsus, total

tarsus, and middle-toe measurements to examine

species pairs and B.c. fulva, they found close to

80 percent of geese were correctly assigned to

their subspecies; however 8 to 9 percent of geese

in the first pair comparisons were incorrectly

classified, and 12 percent in the second pair comparisons were incorrectly classified (table 4).

Pearce and Bollinger (1997) examined measurements of 51 lessers from the Anchorage population, and 52 duskys from the CRD to assess their

ability to morphologically discriminate between

the races. In comparing lesser males with dusky

females, they found 86 to 90 percent accuracy in

separation by using bill width at base. When they

used both bill width at base and bill width at

nares, only 9.8 percent of geese were misclassified. This work is preliminary, and further

analyses are in progress (Pearce 1999).

Genetic Analyses

In the mid-1970s, Timm (1975) submitted Canada

goose blood samples from Cook Inlet (n = 13),

PWS (n = 4), and the CRD (n = 19) to a laboratory at the University of Maryland. Morgan et al.

(1977) confirmed through electrophoresis of

blood serum that all three groups of birds were

distinguishable. The Cook Inlet birds were subsequently identified as lesser Canada geese.

Shields and Wilson (1987b) studied mitochondrial DNA (mtDNA) by using restriction fragment length polymorphisms from five subspecies

of Canada geese: Aleutian (B. c. leucopareia

Brandt), Taverner’s, cackling (B. c. minima

Ridgway), western (B. c. moffitti Aldrich), and

giant (B. c. maxima Delacour). They were able

to clearly differentiate between subspecies and

found a separation between large- and smallbodied Canada geese. By using a calibration

method developed earlier (Shields and Wilson

1987a), they were able to estimate that small and

large forms separated just over 500,000 years

ago. Subspeciation into currently recognized

races began about 150,000 years ago and continued into recent times (Ploeger 1968), a much

shorter period than is typical of subspeciation in

mammals.

Table 4—Error in classification of dusky Canada geese and closely related subspecies

based on 2-step discriminant function analyses of morphological measurements

Subspecies pairs Morphological Sample sizes

comparisons measurements Males Females Error rate

Percent

Lesser - dusky Exposed culmen 141 149 9.0

parvipes-occidentalis Diagonal tarsus

Total tarsus

Lesser - dusky As above, plus 134 144 7.9

parvipes-occidentalis middle toe

Dusky - Vancouver Exposed culmen 326 300 12.6

occidentalis-fulva Diagonal tarsus

Source: Johnson et al. 1979: 70.
6

Scribner et al. (1997, in press) and Pearce et al.

(1998) conducted an extensive study of Pacific

Flyway Canada goose stocks by using nuclear

microsatellite DNA markers and mtDNA sequence data. With the exception of island geese,

combined mtDNA and microsatellite data showed

concordance with taxonomic designations

(table 5). They found a fixed mtDNA difference

between small- and large-bodied birds, as no

mtDNA haplotypes are shared by these two

groups (table 6). Within the large-bodied birds,

mtDNA haplotypes and microsatellite alleles are

shared between populations; however, there is a

statistically significant difference between all

populations based on both mtDNA and microsatellite data. The one exception to shared

mtDNA haplotypes is the unique “H” haplotype

found in island geese only. Ely and Scribner

(1994) have noted that unique haplotypes are

useful for the identification of Canada goose subspecies; however, the “H” haplotype of island

geese differs by only one base pair, derived from

females only. Work on genetic material of male

geese is needed to study gene flow between populations, particularly to elucidate relationships

between CRD geese and island geese.

Pearce et al. (1998) extended and refined the

original work (Scribner et al. 1997) by examining samples of other Canada goose populations

within the Pacific Flyway, increasing the number

of nuclear microsatellite markers examined (from

Buchholz et al. 1998), and increasing mtDNA

sequences to 20 per population (summarized in

Scribner et al., in press). Based solely upon allele

frequency data from nuclear microsatellite markers, they confirmed that dusky Canada geese from

the CRD clearly fit within the large-bodied group

and are distinct from other populations, including

island geese (though the difference here is small).

Replicate sampling through the 100-percent simulations of mtDNA sequencing data yielded confirmation that, similar to results of nuclear DNA

analyses, there was a detectable separation

between CRD geese and island (Green and

Middleton Islands) geese. Accuracy and precision

estimates for assigning breeding geese to their

population of origin indicated that 96 percent (90

percent confidence interval = +4 percent) of CRD

geese could correctly be classified to their point

of origin, with about 3 percent of the birds having

unknown affiliations. Accuracy of classifications

were 86 percent (+8 percent) for Green Island

and 91 percent (+6 percent) for Middleton Island,

with 6 percent and 4 percent, respectively, assigned to unknown populations. If combined,

however, island geese would be classified with

about 95 percent accuracy.

In southwest Washington and western Oregon,

Canada goose seasons are closed if a quota of

duskys is exceeded. Pearce et al. (2000) tested

the use of current morphological and plumage

characteristics to correctly classify CRD dusky

Canada geese by criteria used for regulatory purposes at hunter check stations (USDI Fish and

Wildlife Service 1996). They analyzed genetics

of 106 hunter-shot female Canada geese (Branta

canadensis subsp.) from the wintering grounds in

Washington and Oregon. Of the 50 birds that met

the regulatory criteria for bill length (culmen 40

to 50 mm) and breast color (Munsell 10 YR color

value < 5), 51 percent (90 percent CI = 38 to 64

percent, maximum likelihood estimate) were

estimated to be CRD geese. The remainder of

qualifying birds included 14 percent (CI = 6 to 25

percent) from Middleton Island, 2 percent

(CI = 0 to 6 percent) from Green Island, 11 percent (CI = 3 to 24 percent) from Admiralty Island

(Vancouver Canada geese), and 15 percent of

unknown origin. Of the geese not meeting all of

the morphological and plumage criteria, few were

thought to be CRD or island birds, although there

was a substantial proportion of birds with unknown origins.

Pearce et al. (2000) point out that study results

must be interpreted with caution because (1)

only a one-time sample of hunter-shot geese was

examined, and it may not be representative of

Canada goose composition on the wintering

grounds or in the harvest (e.g., varying geographic distribution throughout the season and

differential vulnerability of subspecies); and (2)

male dispersal makes it more difficult to understand the proportional contribution of breeding

populations to an admixed winter group. These
7

Table 5—Microsatellite DNA allele frequencies (locus 4AC) observed in breeding populations of Pacific Flyway Canada geese. Notehow the diversity and frequency of alleles change across breeding populations, an indicator of the spatial dispersion of geneticvariation that results in high probabilities of population classification

Small-bodied form Large-bodied form

North Yukon Aleutian Copper Green Middleton Admiralty

Slope Delta Island Fairbanks Anchorage R. Delta Island Island Island Washington

Allele (n=22) (n=41) (n=20) (n=18) (n=42) (n=51) (n=30) (n=35) (n=45) (n=17)180 0.01 0.05 0.18182 0.15 0.02 0.01 .12184 .05 .09

186 0.75 1.00 .28 0.58 .68 .50 .35 .34 0.92 .09188 .03 .22 .04 .02 .06 .03190 .03196 .07 .20 .06 .21 .17 .15 .24 .09198 .03 .02 .03 .03 .08200 .07 .20 .14 .01 .15 .23 .26 .06202 .02 .12204 .09 .03 .02 .08 .18 .07 .15206 .06208 .02 .03 .03 .01 .03Source: Pearce et al. 1998.
8 Table 6—Geographic distributions of mitochondrial haplotypes for Canada goose subpopulations sampled across the Pacific Flyway

Sampling Putative Sample mtDNA sequence type (haplotype)location subspecies size A B C D G H I J R F K L M N O P Q S U W X Y ZLarge-bodied formsFairbanks B.c. parvipes 19 19 * * * * * * * * * * * * * * * * * * * * * *

Anchorage B.c. parvipes? 19 9 1 * * * * * 7 2 * * * * * * * * * * * * * *

Copper R. Delta B.c. occidentalis 20 * 9 7 * * * 4 * * * * * * * * * * * * * * * *

Green Island B.c. ? 23 * * * * * 23 * * * * * * * * * * * * * * * * *

Middleton Island B.c. ? 26 * * * * * 26 * * * * * * * * * * * * * * * * *

Admiralty Island B.c. fulva 17 4 * 13 * * * * * * * * * * * * * * * * * * * *

Washington B.c. moffitti 15 13 * * 2 * * * * * * * * * * * * * * * * * * *

Small-bodied formsNorth Slope B.c. taverneri 8 ** * * * * * * * * 6 2 * * * * * * * * * * *

Yukon Delta B.c. minima 17 * * * * * * * * * 2 * 10 * * * * * 2 2 * * 1 *

Aleutian Islands B.c. leucopareia 22 * * * * * * * * * * * 13 2 4 1 1 1 * * * * * *

Hunter-shot sample 93 36 9 13 * 2 10 5 2 * * * 4 * * * * * 1 4 1 1 2 3

Note: Analyses are based on sequence analysis of 144 base pairs of a hypervariable portion of the control region.Source: Pearce et al. 1998.
9

factors are currently being assessed (Pearce

1999). It seems clear, however, that because the

check-station classification criteria for duskys

encompass a proportion of non-CRD and nondusky geese (at least among females), estimates

of dusky harvest are likely to be somewhat inflated. As a result, the quota system operates conservatively, erring on the side of conservation.

Perspectives on Taxonomy for This

Report

Differentiation of Canada geese along the north

Pacific coast has apparently been a recent phenomenon in geologic time. Given the geologically

young age and very active status of the Pacific

coast, and the retreat of glaciers from the region

only 10,000 years ago (Pewe 1975), it is not surprising that coastal populations of geese are also

“young” and thus closely related (Ploeger 1968).

The term “geologically young” certainly describes the CRD, where a cycle of uplift and

subsidence has characterized the region for thousands of years (Plafker 1990). With this process,

coastal marsh habitat has varied dramatically in

both quantity and quality. Canada geese occupying the area must certainly have struggled to keep

pace with the changes and adapted, or not, as

conditions permitted. Faced with these circumstances, managers have necessarily adopted practical guidelines for managing groups of breeding

geese while more detailed studies of subpopulations are being conducted and taxonomic decisions are pending.

Although managers recognize that island-nesting

geese of PWS and Middleton Island exhibit minor but unique genetic characteristics (see “Genetic Analyses” above), island geese and CRD

geese are currently considered to be subpopulations of dusky Canada geese based on several

considerations: (1) the degree of difference between CRD geese and island geese is small compared to differences with more distant groups in

Cook Inlet or southeast Alaska, (2) the two

groups are indistinguishable to observers in the

wild, and (3) they winter sympatrically. This assessment focuses on dusky Canada geese of the

CRD because this is the main body of the subspecies population. It is also the subpopulation experiencing decline and uncertainty, whereas island

geese have been stable or increasing in number.

Nevertheless, potential interactions between subpopulations may prove to be important in the

long-term conservation of duskys, so they are

briefly discussed.

On the wintering grounds, CRD duskys and other

large dark geese are managed in the aggregate

based on evidence that the wintering flock of

large dark geese is composed of a mixture of

subspecies and subpopulations (Hansen 1962,

Pacific Flyway Council 1997, Ratti and Timm

1979). Recent evidence confirms this finding

(see “Genetic Analyses” above, and Pearce et al.

2000). In addition, telemetry and neck collar observations demonstrated that geese from Green

and Middleton Islands indeed winter sympatrically with CRD geese in the Willamette Valley

(ADFG 1999, Crowley et al. 1998). Johnson et al.

(1979) pointed out that information from banding

is usually more valuable than simply knowing the

subspecies classification of birds, because management usually requires more precise data, and

a subspecies often is composed of several populations. Thus, although the wildlife agencies manage island geese collectively with CRD birds as

the dusky goose population, they are committed

to conservation of specific breeding populations

regardless of taxonomic designations.

Population Delineation and

Distribution

Breeding Range

Historical notes—Early investigators considered

all large dark Canada geese breeding along the

Pacific coast, i.e., from PWS south to the Queen

Charlotte Islands (QCI), British Columbia, to be

occidentalis. Baird et al. (1884) reported that

occidentalis occurred along the northwest coast

from Sitka to California. However, Grinnell

(1910 in Delacour 1951) noted that,
10

The Prince William Sound birds are still

darker, even, than the Sitkan district

birds... It will be noted from the accompanying table of measurements that the

PWS birds are decidedly smaller than the

Sitkan district examples....Taking both

coloration and size into account, the

systematic status of these birds is decidedly unsatisfactory. I am using the name

occidentalis for them only as a makeshift.

Swarth (1911) concurred with this view. Initial

observations were few, and any records were of

interest. Dixon (1908) found a nest in thick underbrush near a large tree on Hawkins Island in

PWS. Bailey (1927) concluded that Canada

geese, identified as occidentalis (which included

birds classified today as fulva), were resident

year-round in southeast Alaska, although he suspected that most were migratory. He found breeding Canada geese to be common in Glacier Bay in

mid-June.

Moffitt (1937) concluded a review of distributional records of occidentalis by noting that the

largest forms of the race apparently breed in the

southern part of their range, from Vancouver Island to Glacier Bay, as found earlier by Grinnell

(1910) and Swarth (1911). Upon his death,

Moffitt’s extensive notes were combined with the

indepth work of Jean Delacour, and the subspecies occidentalis was split to recognize the new

subspecies fulva distinct from occidentalis

(Delacour 1951). Delacour considered fulva resident on the islands and along the coast of British

Columbia and southern Alaska, from north of

Vancouver Island to Glacier Bay. Occidentalis

bred around PWS, Alaska, and perhaps farther

south and north, intergrading with taverneri inland and with leucopareia to the northwest. Early

banding by Fred Robards and Urban Nelson provided the first definitive evidence that duskys

from the CRD migrated south for the winter

(Nelson 1953). Gabrielson and Lincoln (1959)

considered the breeding range of duskys to include the regions of PWS, Cook Inlet, and inland

through the Copper River drainage. They also

noted that numerous flocks occurred in Yakutat

Bay during spring.

Using extensive aerial survey experience, Hansen

(1962: 303) delineated the breeding range of

duskys, which extended “along the coast from the

vicinity of the Bering Glacier on the southeast to

Cook Inlet on the west, a distance of about 275

miles” (440 km). He noted that only small numbers of geese occurred in PWS and the lower

Susitna River, Cook Inlet, and even fewer near

the confluence of the Bremner River with the

Copper River. Hansen clearly defined two zones

essentially devoid of breeding Canada geese,

because of habitat differences, that helped to

define and isolate the range of duskys from those

of Taverner’s (250 km to the northwest) and

Vancouvers (500 km to the south).

Contemporary understanding—Geese breeding

on Cook Inlet, Alaska, were identified as lesser

Canada geese in the mid-1970s (Timm 1975,

1976). Thus, the breeding range of duskys is no

longer considered to extend that far to the northwest. The primary nesting range of occidentalis

remains the CRD, Alaska (fig. 1). This distribution extends eastward through Martin Lake to

include the lake at the foot of the Bering

Glacier (Frair and Liska 1998).

Island geese nest on Middleton Island and in narrow coastal strips of both the islands and the

mainland of PWS, Alaska. Island geese in PWS

are most prevalent in the southern and eastern

regions of the sound (Isleib 1977, Isleib and

Kessel 1973, Nysewander and Knudtson 1977),

with highest numbers occurring on Montague,

Hinchinbrook (especially Constantine Harbor)

(Kurhajec 1977, Nysewander and Knudtson

1977), and Hawkins Islands, and along the shores

of Orca Inlet and Orca Bay. Small numbers occur

in northern PWS near the Columbia Glacier and

on Green and Gravina Islands (Crowley et al.

1998, Isleib 1977). Middleton Island has hosted

about 1,400 breeding adult geese in recent years

(Petrula et al. 2002), but the number of island

geese in PWS is unknown.

Transplant to Willapa Bay, Washington—In

accord with a previous USFWS policy to establish breeding Canada goose flocks, 41 dusky goslings were transplanted from the CRD to the

Willapa National Wildlife Refuge in July 1958,
11

Figure 1—The primary nesting range of Branta canadensis occidentalis is the Copper River Delta, Alaska, extending eastward to the

coastal front of the Bering Glacier.
12

of which 38 survived to 1961 when successful

nesting began. This flock grew to become freeflying by 1967. In 1971, 95 pinioned birds were

transported to William L. Finley National Wildlife Refuge in Oregon; their fate was unmonitored

and is unknown. The Willapa flock continued to

grow and was 407 birds in 1977 (Welch 1978).

Refuge personnel now distinguish between migrant duskys, resident duskys, and dusky hybrids

(Atkinson 1987). About 120 to 175 resident birds

are still associated with the refuge; however, the

total regional number of resident duskys and

dusky hybrids is unknown.

Transplant to Middleton Island, Alaska—

Middleton Island hosted no breeding Canada

geese prior to 1978 (Hatch in Campbell 1987,

Rausch 1958). By 1981, however, a small number

of geese had become established there as breeders. These geese were tentatively identified as

duskys (Campbell 1987, Gould and Zabloudil

1981, Isleib 1986). In an effort to enhance the

dusky goose population as a whole, duskys

from the CRD (49 male, 47 female goslings;

1 male and 9 female adults) were transplanted to

Middleton Island in July 1987 (Campbell et al.

1988). The island was considered a good prospect

for enhancement because it was free of mammalian predators and it had a small established

breeding population of geese. A subsequent transplant of 35 male and 48 female goslings and 3

adult females was done in July 1988 (Campbell

and Rothe 1989). A third transplant, scheduled

for 1989, was cancelled because of poor return

rates of previously transplanted birds, unexpected

high levels of predation by eagles, and poor gosling production on the CRD. Ultimately, the

transplant program was discontinued because the

naturally established Middleton geese seemed to

be increasing (Campbell and Rothe 1990).

Annual monitoring from 1987 to 1992, and

again in 1996, 1997, 2000, and 2002 revealed

a rapid and natural increase in the Middleton

geese, from about 100 birds in the first year to

over 2,200 geese by 1996 and 2,500 in 2000

(Campbell 1991c; Campbell and Rothe 1989,

1990; Campbell et al. 1988, 1992; Crowley

et al. 1997; Petrula 2000; Petrula et al. 2002;

Rosenberg et al. 1996). Investigators concluded

that the transplants from CRD had contributed

very little to this irruption (Campbell et al. 1992),

and subsequent genetic analyses confirmed that

Middleton geese were essentially the same as

island-nesting geese (Pearce et al. 1998). Of six

collared geese observed on Middleton Island

from 1988 to 1997, three were birds transplanted

there as female goslings, and three were banded

on the CRD as after-hatching-year birds (two

males banded in 1991, one female banded in

1988).

Wintering Range

Historical notes—Baird et al. (1884) reported

that occidentalis occurred as far south as California. Dawson (1909) noted that occidentalis migrated through the Washington coast area but was

not a common resident in Puget Sound. Brooks

(1917, 1923) reported large dark geese in interior

British Columbia and near Porcher Island on the

coast. In his later report, he mentioned that the

geese resident near Porcher Island likely belonged to the large dark race occurring on QCI

and generally identified as occidentalis, but he

may have been referring to the large-bodied form,

later classified as fulva.

Specimens of occidentalis were reported from

several places in Oregon, including the coastal

areas of Gold Beach and Netarts Bay, and for

the first time including specimens from the

Salem and Eugene areas in the Willamette Valley

(Jewett 1932). Moffitt (1937) reviewed the taxonomy and distribution of occidentalis and confirmed the presence of the race in northern

California, specifically near Ferndale, Humboldt

County (about 200 geese in 1932), near Eel River

(about 225 in 1933), and at Crescent City (about

150). He reported observations of about 300 birds

between Eureka and Capetown in 1937.

In the late 1930s, occidentalis apparently still

wintered largely along the Oregon coast, with

only occasional stragglers inland (Gabrielson and

Jewett 1940). However, during the late 1930s and

through the mid-1940s, large dark geese, presumably occidentalis, were observed to be common
13

spring and fall migrants and winter visitors in the

southern Willamette Valley, outnumbering the

light geese in a ratio of 2:1 (Gullion 1951).

Delacour (1951), in his review of Canada

goose subspecies and splitting off of fulva from

occidentalis, noted that occidentalis wintered at

least as far south as Oregon.

Jewett (1953) reported observations and harvest

of duskys from throughout the Willamette Valley

(Corvallis, McMinnville, Rickreal) and Sauvie

Island, Oregon, from 1931 through 1952. He

noted that “this coastal species [is] fairly common along the ocean beaches the entire length

of Oregon, but is becoming either better known

to hunters, or is actually increasing during the

fall and winter months in the Willamette Valley

and Lower Columbia River Valleys.” In Birds of

Washington State, Jewett et al. (1953) reported

few records, with observations restricted to the

coastal fringe, but concluded that the race was

probably much more common than present information indicated.

Finally, Hansen (1962) compiled an extensive

data set based on 1,129 recoveries of 3,943

duskys banded on the CRD, and on 164 recoveries of 3,593 Vancouvers banded in the vicinity of

Glacier Bay, to demonstrate that to a great extent

their ranges were discrete, and that duskys wintered primarily in the Willamette Valley. Based

on band recoveries, duskys largely bypassed

coastal Alaska in fall migration, stopping en route

south in the QCI and on Vancouver Island, where

a few overwintered. Most continued on to

Willapa Bay (where small numbers wintered),

then up the Columbia River to winter primarily

in the Willamette Valley. An aberrant few wintered on the northwest coast of California.

Hansen (1962: 307) estimated that about 1,000

to 1,500 duskys wintered in PWS; Isleib and

Kessel (1973) observed a few to hundreds of

Canada geese wintering there. In contrast,

Vancouvers were largely sedentary in southeast

Alaska and British Columbia, with relatively

few birds migrating to winter on the coast of

Washington and in the Willamette Valley.

Interestingly, although the type specimen for

Vancouvers was collected on the QCI, only dusky

bands were recovered there (Hansen 1962: 319).

By the mid-1960s, just prior to the effective establishment of refuges, concentrations of duskys

wintering in the Willamette Valley had shifted

from the southern end of the valley to the middle

valley, particularly to the Oak Knoll complex

near Corvallis and Albany (Chapman et al. 1969).

Contemporary understanding—Dusky Canada

geese primarily winter in the Willamette Valley of

Oregon and in the lower Columbia River

Valley of Washington and Oregon (fig. 2).

Cornely et al. (1998) identified 11 core areas used

by wintering duskys in the mid-1980s in Washington (from Willapa National Wildlife Refuge

through the Columbia River valley islands) and

in Oregon (Sauvie Island and several locations

throughout the Willamette Valley from southwest

of McMinnville to the Fern Ridge Reservoir near

Eugene). They also found that a small number of

birds collared on the CRD wintered in PWS near

Whittier; near Craig on Prince of Wales Island,

southeast Alaska; on the QCI, British Columbia;

and on Vancouver Island, British Columbia.

Sightings of duskys were made through all winter

months at the Delkatla Wildlife Refuge, QCI,

indicating that some birds wintered there. Between the winters of 1982-83 and 1995-96, peak

midwinter counts of 300 to 850 geese were considered to be primarily duskys (Hearne 1999).

Similarly, Macgregor (1993) and VanderPol

(1997) confirmed the presence of dusky geese

(neck-collared on CRD) wintering on the Saanich

Peninsula of Vancouver Island in flocks of 50 and

60 geese, respectively, throughout the 1990s.

In recent years, small numbers of duskys have

consistently used Willapa Bay (fig. 2), particularly the Willapa National Wildlife Refuge and

the Nelson Ranch. Numbers overwintering there

have been estimated at 600 to 750 in Willapa

Bay during the mid-1980s (Anonymous 1986,
14

Figure 2—Winter distribution of dusky

Canada geese based on observations

of unique neck collars of Copper

River Delta birds, 1985-1991

(Naughton 1992).

Atkinson 1987); numbers on the refuge, typically

around 200 to 300, have ranged from 130 to 800

birds during winters from 1986-87 to 1992-93

(Atkinson 1987, 1988, 1989, 1990, 1991, 1992;

Murphie 1993). Other areas consistently used

include Chehalis Bay, south Gray’s Harbor, and

Wallace, with small numbers at Silver Lake and

La Center, and possibly Port Susan Bay (Kraege

1995).

Small numbers of duskys still winter along the

Oregon coast (fig. 2): about 500 to 700 in

Nestucca Bay, Tillamook County, and about

100 at Goat and Prince Islands using pastures

along the Smith River just inside California

(Lowe 1987).

There is strong evidence that island geese winter

sympatrically with CRD duskys. In summer

1998, 4 geese on Green Island and 20 geese on

Middleton Island were marked with VHF radios

on neck collars; 12 additional geese on Middleton

were marked only with collars. During November

1998 through April 1999, all 4 (100 percent) of

the Green Island birds, and 24 (75 percent) of the

Middleton geese were detected in Oregon and

Washington on the traditional wintering area of

duskys (ADFG 1999).

Migration

Fall—Little is known about the specific routes

and timing of movements of duskys during migration. Hansen (1962) suggested that they migrate

offshore, seldom stopping during the fall migration to wintering areas. Hawkings (1982) and

Mickelson et al. (1980) reported that duskys began arriving on the eastern CRD from the western CRD in early August as nonbreeders regained

flight after the molt. The movement continued

with geese staging on the eastern CRD throughout September, prior to departure in early to mid

October (although a few duskys had not yet

departed when observers left in mid-October).

Grand (1997) found that two radio-marked birds

moved from core nesting areas on the western

CRD to the Bering Glacier and Martin Lake area,
15

just off the CRD to the northeast (fig. 1), about

the time of molt. Crowley (1999a) reported 110

geese on Hinchinbrook Island, PWS, in September 1996, 5 of which were duskys collared on the

CRD, indicating the possibility of similar dispersal and staging to the west prior to migration.

Crouse (1994a) conducted aerial surveys of the

Copper and Bering River deltas in fall 1992 and

observed that large numbers present on 2 October

were greatly reduced by 14 October.

Geese are known to use the Yakutat Forelands

for fall staging (Petersen et al. 1981), but there

are few other known sites within Alaska. Some

areas used by geese during fall migration, as

determined from leg-band returns, include the

southwest coast of Prince of Wales Island,

Alaska; Graham Island, British Columbia; the

northern tip and west-central coast of Vancouver

Island, British Columbia; and the southern interior of British Columbia (Hansen 1960). Duskys

also use the QCI, British Columbia. Hearne

(1999) has provided observations of duskys that

use the Delkatla Wildlife Sanctuary at Masset,

Maast Island, and the Port Clements area, including Kumdis Bay and Slough, the Yakoun Estuary,

and Stewart Bay in the QCI. Geese departing

Vancouver Island, along with birds passing that

point, fly to Gray’s Harbor and Willapa Bay,

Washington (Chapman et al. 1969). Dawson

(1909) reported that occidentalis migrate through,

but are not a common winter resident in Puget

Sound, Washington. From the southwest Washington coast, the majority of the population

moves up the Columbia River to the mouth of

the Willamette River where most turn south until

settling in the central Willamette Valley

(Chapman et al. 1969).

Leg-band recoveries give a gross level of distribution for geese during the migration period

(table 7), reflecting concentration sites for geese

that are accessible to hunters. The distribution of

band recoveries generally reflects the observations discussed above.

Spring—Information is even more scant for the

distribution of duskys during spring migration.

Duskys briefly build on Sauvie Island, Oregon, in

the lower Columbia River (LCR) valley as the

migration begins, and a subsequent surge in numbers is observed at Willapa Bay, Washington. A

brief increase in geese is noted also at the QCI,

British Columbia. Large flocks have been observed in Yakutat Bay, southeastern Alaska, in

spring (Gabrielson and Lincoln 1959, Petersen

et al. 1981). Mickelson et al. (1980) observed

duskys on the eastern CRD descending from altitudes greater than 150 m during mid-April 1979.

Hawkings (1982) concluded that most of the

spring migration of duskys through the eastern

CRD had already occurred when observations

began on 23 April 1978. In 1979, Hawkings

(1982) observed duskys moving through the area

when observations began on 16 April, with the

last major movement observed on 21 April.

Mickelson et al. (1980) and Hawkings (1982)

found that most duskys migrated through the area

without stopping during spring. Crouse (1994a)

surveyed the Copper and Bering River deltas

weekly from 1 April through 1 May. Few geese

were observed on 1 April, and numbers peaked

on 23 April. Important use areas included Okalee

Spit on 1 and 8 April, and coastal areas between

the Edward and Bering Rivers during the 16 April

surveys. Geese were present on the CRD during

surveys on 8 and 16 April, and a large movement

onto the area was noticed on the 23 April survey

(Crouse 1994a).

Significant Events in Recent

History of Dusky Canada

Geese

Alaska Earthquake 1964

On 27 March 1964, an earthquake lasting 4 to 5

minutes, and of Richter magnitude 8.4 to 8.6 occurred in Alaska, with the main epicenter 130 km

west of the CRD. This event has had major effects on the CRD because of the 1.8 to 3.4 m

uplift of the land surface relative to sea level

(Hansen and Eckel 1971, Reimnitz and Marshall

1971). Important ecological changes were predicted (Shepherd 1966) and have largely come to

pass (fig. 3). As a result of the uplift and the associated cessation of tidal flooding, the rate of plant

community succession on the CRD has been
16

Table 7—Percentage distribution of leg-band returns from dusky Canada geese in the

Pacific Flyway, 1951-1994

Hunting British

season n Alaska Columbia Washington Oregon Other

 – – – – – – – – – – – – – Percent – – – – – – – – – – – – – –

1951 3 0.0 0.0 0.0 100.0 —

1952 35 17.7 2.9 5.7 74.3 —

1953 105 8.6 24.8 8.6 58.1 —

1954 201 10.0 7.0 18.4 64.2 0.5a

1955 92 5.4 4.3 9.8 80.4 —

1956 86 4.7 26.7 9.3 59.3 —

1957 172 4.1 22.1 8.1 64.5 1.2a

1958 135 4.4 14.1 11.1 70.4 —

1959 140 7.1 22.1 4.3 66.4 —

1960 156 5.1 19.9 17.3 57.7 —

1961 48 12.5 18.8 12.5 56.3 —

1962 105 13.3 11.4 11.4 63.8 —

1963 123 5.7 15.4 6.5 69.9 2.4a

1964 64 4.7 7.8 18.8 68.8 —

1965 112 7.1 14.3 14.3 63.4 .9a

1966 95 9.5 7.4 3.2 80.0 —

1967 73 8.2 6.8 16.4 68.5 —

1968 96 9.4 17.7 10.4 62.5 —

1969 97 10.3 10.3 11.3 68.0 —

1970 159 10.7 8.2 8.8 72.3 —

1971 67 11.9 6.0 9.0 73.1 —

1972 103 9.7 0 8.7 80.6 11a

1973 66 18.2 4.5 10.6 66.7 —

1974 191 13.6 5.2 13.6 67.5 —

1975 194 13.9 5.2 13.9 67.0 —

1976 235 10.2 10.6 14.0 64.7 .4b

1977 243 16.5 4.9 9.1 69.1 .4a

1978 236 24.2 2.1 13.6 57.6 2.5a c

1979 98 16.3 2.0 12.2 69.4 —

1980 104 2.9 2.9 8.7 84.6 1a

1981 69 4.3 0 10.1 85.5 —

1982 33 24.2 0 9.1 63.6 3d

1983 76 6.6 0 5.3 88.2 —

1984 62 21.0 8.1 8.1 63.0 —

Mean 10.4 9.2 10.4 69.7 0.4
17

Table 7—Percentage distribution of leg-band returns from dusky Canada geese in the

Pacific Flyway, 1951-1994 (continued)

Hunting British

season n Alaska Columbia Washington Oregon Other

 – – – – – – – – – – – – – Percent – – – – – – – – – – – – – –

1985 37 10.8 18.9 37.8 32.4 —

1986 17 17.6 17.6 11.8 52.9 —

1987 29 27.6 17.2 10.3 44.8 —

1988 25 40.0 16.0 24.0 20.0 —

1989 44 54.5 4.5 11.4 29.5 —

1990 40 44.4 6.7 26.7 22.2 —

1991 19 52.6 0 15.8 31.6 —

1992 26 30.8 3.8 19.2 38.5 7.7e

1993 9 11.1 0 33.3 55.6 —

1994 13 38.5 0 15.4 46.2 —

Meanf 32.8 8.5 20.6 37.4 0.8

a

 California.

b

 Minnesota.

c

 Utah.

d

 Idaho.

e North Dakota and Wyoming.

f

 Period of significant restrictive harvest regulations after 1984.
18

Figure 3—Photos of the Copper River Delta, Alaska, illustrating habitat changes caused by the 1964 earthquake.
19

greatly enhanced (Potyondy et al. 1975, Shepherd

et al. 1967, Thilenius 1995), leading to detrimental effects on productivity and survival of duskys.

As succession proceeds, open habitat supporting

salt-tolerant species has become increasingly

closed habitat as the growth of shrubs and trees

has been promoted. Predators of geese and their

eggs have become more prominent and effective

as habitats have become more favorable to them

(Campbell 1990a, Shepherd 1966). Concurrently,

a “new marsh” zone is developing slowly along

the outer CRD as graminoid species occupy

former intertidal flats that were uplifted

(Reimnitz and Marshall 1971; Thilenius 1990a,

1995). Accelerated woody plant succession

(Thilenius 1990b), accompanying changes in

fauna, and the development of new marsh are

continuing on the CRD today; thus, both direct

and indirect changes to the habitats of geese,

many of which are not predictable, will continue.

Establishment of Refuges on Wintering Grounds

In the late 1950s, managers recognized the need

for additional management of harvest and habitats within core wintering areas of duskys (USDI

Fish and Wildlife Service 1980). Hansen (1962:

317) confirmed “A shortage of wintering habitat

is probably the greatest limiting factor at present.” He noted that a majority of the population

wintered within 32 km of Corvallis, Oregon, and

that a concentration of nearly one-third of this

winter population occurred in one small area 13

km south of that community. Thus, in the mid1960s, several federal refuges were established to

provide wintering habitat for geese in Washington

and Oregon. These refuges have played an important role in the wintering biology and management of dusky Canada geese.

Wintering Ground Complex of

Canada Goose Subspecies

During the 1800s, early naturalists visiting the

Willamette Valley noted only a few small Canada

geese that they referred to as Hutchin’s geese

(B. c. hutchinsii) (see Aldrich 1946), and some

large Canadas referred to as B. c. canadensis

(Anthony 1886, Johnson 1880, Townsend

1839, Woodcock 1902). Jarvis and Bromley

(1998) assumed these authors were seeing B. c.

taverneri, B. c. parvipes, or both for the small

race, and moffitti for the large race. By the 1950s,

however, most geese in the valley were large,

dark Canada geese, presumably duskys, while

one-third were light-colored Canada geese

(Gullion 1951). There was an apparently brief but

substantial “intrusion” of other geese during the

winter of 1959-60 (Hansen 1962) that inflated the

midwinter inventory of duskys, but by the time

refuges were established in the mid-1960s, other

races were rarely mentioned in discussions of

geese in the valley. Chapman et al. (1969) found

96 percent of geese checked in the possession of

hunters during the 1965-66 season, and 99 percent during the 1967-68 season, were duskys.

Smith (1971) estimated 90 to 94 percent of the

wintering geese were duskys. Thus, harvest estimates, harvest regulations, and population surveys on the wintering grounds of the duskys were

straightforward.

By 1973, however, an increase in other races

was becoming apparent (Pacific Flyway Council

1973). The subsequent buildup of Taverner’s

and lessers to 85 percent of the wintering Canada

geese by winter 1977-78 (Simpson and Jarvis

1979), the occurrence of Vancouver and Aleutian

Canada geese (Jarvis and Cornely 1988), and the

more recent increase of cackling and western

Canada geese (Jarvis and Bromley 1998) on the

wintering grounds is well documented. Much of

this response, given the abundant nutritious food

provided by agriculture, likely was due to management practices that were designed to benefit

duskys, but yielded even greater benefits to other

races within the wintering area (Simpson and

Jarvis 1979, Timm et al. 1979). The midwinter

index of Canada geese in the Willamette Valley

during 1997-98 was 133,000 (Pacific Flyway

Council 1998), up from about 25,000 in the

early 1970s, while the proportion that is dusky

dwindled to an estimated 6 to 16 percent in recent

years (Pacific Flyway Council 1997). In fact, the

situation may be even more extreme. The actual

population of Canada geese wintering in the

Willamette Valley may be two to three times
20

larger than the index (Pacific Flyway Council

1998: 7), making the duskys a much smaller

segment of the wintering population.

Management challenges have arisen because

duskys are much more susceptible to hunting

mortality than are sympatric races of Canada

geese, and because estimation of harvest and

population size has become much more difficult given the presence of look-alike populations (Timm et al. 1979). Vulnerability of duskys

to hunting, relative to Taverner’s geese, is 2.7 to

3.0 times higher (Jarvis and Cornely 1988,

Simpson and Jarvis 1979), so hunting regulations must be finely crafted to effectively protect

duskys. Coincidentally, regulations that favor

duskys have greatly benefited other races, leading

to a soaring Canada goose population wintering

within the range of duskys. Thus, managers had

to develop unique methodology to both distinguish duskys from other races in the harvest

(Johnson et al. 1979, USDI Fish and Wildlife

Service 1996) and to estimate midwinter population size of duskys (e.g., Drut et al. 1997, Jarvis

1992, Sheaffer and Jarvis 1995). Finally, burgeoning numbers of wintering Canada geese and

high vulnerability of duskys to hunting mortality

led to the development of unique hunting regulations permitting the take of other races while

largely protecting duskys from harvest, and of a

crop depredation control plan to minimize crop

damages resulting from high wintering populations of geese (Pacific Flyway Council 1998).

Biology

Reproduction

Chronology—The first dusky Canada geese arriving in spring on the CRD are frequently observed in March (Campbell and Rothe 1985,

Crouse et al. 1997, Isleib 1986). Major influxes

occur some time later (table 8), apparently depending on weather conditions and the state of

spring snowmelt. In 1964, inclement spring

weather delayed the arrival of geese by 3 weeks

compared to normal (Shepherd 1965). Records

of major arrival dates (table 8) range from 9 April

(Campbell and Rothe 1986, Crouse et al. 1997) to

18-25 April (Bromley and Jarvis 1993).

Peak nest initiation (laying) dates (table 8) have

varied annually from 29 April-5 May 1992

(Campbell 1992a) to early June 1972 (Timm

1972b, and Timm and Havens 1973). On the

eastern CRD, initiation dates in 1978 and 1979

ranged from 6 to 31 May, with a peak from 6 to

11 May (Mickelson et al. 1980). Renesting

occurs, especially in years of high loss of early

nests, causing the period of nest initiation to be

much longer than for first nests, and in some

years resulting in a bimodal distribution (fig. 4)

of initiation dates (e.g., Campbell et al. 1987,

Grand et al. 1998). Duration of the initiation

period was 30 days in 1974 and 39 days in 1975

(Bromley 1976), and averaged 38 days, with a

maximum of 50 days, from 1993 to 1995 (Crouse

et al. 1997). Shepherd et al. (1967) found that a

severe storm in mid-May 1966 interrupted nest

initiation and caused nest abandonment and delayed initiation such that there were three distinct

ages of goslings observed later in the summer.

Using brood ages, Olson (1953,1954b) estimated

peak hatch dates of 20-25 June 1953 and 22-27

June 1954. Other peak hatch dates were about 1

July 1971 (Timm and Havens 1973) and 12-18

June 1974 and 17-23 June 1975 (Bromley 1976).

Crouse et al. (1997), for the years 1993-95, noted

earliest hatch dates of 4 June in 1994 and 1995,

and 13 June 1993, with median hatch dates of 27

June 1993 and 17 June 1995.

By 5 August 1953, about one-third to one-half

of young observed could fly, whereas one-quarter

of the young were capable of flight on 5 August

1954 (Olson 1954b). An estimated one-half to

three-quarters could fly by 12 August that year

(Olson 1954a). Trainer (1959) estimated that 5

percent of goslings were still flightless on 19

August 1959, and Bromley (1976) noted a few

flightless young as late as the second week of

September.

Energetics of reproduction—Bromley and

Jarvis (1993) studied the energetics of migration

and reproduction of duskys during three reproductive seasons, 1977-79. They found that during

spring hyperphagia on the wintering grounds in
21

Table 8—Peak arrival and nest initiation dates, duration of the prelaying period, and mean

clutch size of dusky Canada geese on the Copper River Delta, Alaska, 1959-1998

Major Peak nest Approx. duration Mean clutch

Year arrival initiation of prelay period size (n) Source

1959 — first nest 6 May — 5.6 (194) Trainer 1959

1964 delayed 3 weeks — 4.3 (114) Shepherd 1967

1965 — — — 5.8 (140) McKnight 1971

1966 — — — 4.8 (100) Shepherd et al. 1967

1968 — — — 5.1 (75) Timm and Havens 1973

1970 — — — 5.4 (146) McKnight 1971

1971 — 3 weeks late — 3.6 (113) Timm 1972b

1972 — very late — 4.4 (57) Timm and Havens 1973

1973 — — — 4.9 (48) Timm 1974

1974 25 Apr 9-14 May 13 days 5.6 (81) Bromley 1976

1975 22 Apr 16-21 May 24 days 4.8 (215) Bromley 1976

1976 — — — 4.8 (168) Timm 1977

1977 17-22 Apr 2-7 May 16 days 5.4 (181) Bromley and Jarvis 1993

1978 14-20 Apr 1-9 May 17 days — — Bromley and Jarvis 1993

1979 18-25 Apr 3-7 May 15 days 5.7 (338) Bromley and Jarvis 1993

1980 — — — 5.4 (152) Timm 1982

1981 — — — 4.9 (28) Timm 1982

1982 — — — 4.8 (135) Campbell and Timm 1983

1983 — 6-10 May — 5.5 (87) Campbell 1984

1984 9-15 Apr 3-8 May 12-19 days 5.6 (123) Campbell and Rothe 1985

1985 15-21 Apr 27 May-1 June 43 days 4.4 (64) Campbell and Rothe 1986

1986 — 5-12 May — 4.9 (78) Campbell et al. 1987

1987 early Apr 5-12 May 30 days 5.5 (121) Campbell et al. 1988

1988 — 8-14 May — 5.5 (52) Campbell and Rothe 1989

1989 20 Apr 11-17 May 22 days 5.3 (25) Campbell and Rothe 1990

1990 26-31 Mar 8-17 May 38 days 5.3 (50) Campbell 1990a

1991 31 Mar-6 Apr 10-16 May 35 days 5.4 (51) Campbell 1991c

1992 mid-Apr 29 April-5 May 27-35 days 5.1 (93) Campbell et al. 1992

1993 9-13 Apr — 21+ days 5.1 (24) Crouse et al. 1997

1994 8-12 Apr about 22 May 20-30 days 5.1 (58) Crouse et al. 1997

1995 31 Mar-3 Apr about 2 May — 5.6 (65) Crouse et al. 1997

1998 early Apr 28 Apr- ? 20 days — — Youkey 1998
22

Figure 4—Bimodal distribution of dusky Canada goose nest initiation dates on the Copper

River Delta, Alaska, typical of years when there is a considerable degree of renesting after

high rates of early nest depredation. Nest initiation dates from Alaganik Slough study area

(from Grand et al. 1998).

the Willamette Valley, geese accumulated large

lipid reserves (30 percent of body mass) that were

subsequently depleted by over 50 percent during

the spring migration of 2600 km to the CRD.

During the prenesting period on the CRD, however, geese restored some of their lipid reserves,

increased their protein reserves, and met the costs

of egg formation through intensive feeding on

new, high-quality spring growth of vegetation.

The energy and nutrient costs of egg laying were

high, and were met largely through feeding and to

a lesser extent by drawing upon reserves, particularly protein reserves. Catabolism of lipid and

protein reserves accounted for about 75 percent

of the estimated costs of incubation, with food

consumed during incubation recesses meeting the

remaining requirements. The energetics of subsequent stages in the life history of duskys has not

been investigated.

Prenesting—Raveling (1978) hypothesized that

some geese time their arrival on nesting grounds

to permit the period of rapid development of ovarian follicles to occur there so that nest initiation

(laying of the first egg) would be uniquely synchronized with annual snowmelt conditions, and

that this period would be a minimum of about

12 days for Canada geese. Duskys, for which the

minimum prelaying period (peak arrival to peak

nest initiation) is about 13 days (Bromley and

Jarvis 1993), appear to fit this pattern (table 8).

For duskys arriving on the CRD, ovarian follicles

were increasing in diameter at a slow rate of <0.1

mm per day. However, when geese subsequently

entered the stage of rapid development of ovarian

follicles some time after arrival, growth rates increased more than twentyfold, to >2 mm per day

(Bromley and Jarvis 1993).

Incubation—Trainer (1959) determined a mean

incubation period (i.e., “the number of days between the laying of the last egg and the hatching

of the last egg”) of 30.2 days (n = 36, range = 28

to 33 days). However, Bromley (1976), defining

incubation as the period from the day after the

last egg was laid to hatch of the first egg, found a

mean of 27.4 days (n = 21, range = 25 to 31

days). Possibly the chilling effect of tidal flooding (Hansen 1961, Trainer 1959) slowed embryo

development (e.g., Bromley 1984, Drent 1973)
23

and led to a longer incubation period during

preearthquake times.

Constancy of incubation for successful dusky

females was 89.5 percent, with twice the amount

of recess time during the last third compared to

the first two-thirds of incubation (Bromley 1984).

This pattern reflected changes in body weight,

where steep declines were observed for the first

two-thirds of incubation, and no change thereafter. Females switched emphasis from dependence

on endogenous reserves to a much greater reliance on environmental food resources during the

last phase of incubation. Constancy of incubation

and recess frequency steadily declined during the

first 13 days of incubation for unsuccessful nesting geese, whereas no change was detected during this period for successful nesters (Bromley

1984).

Reproductive parameters—Eggs of dusky

Canada geese on the CRD average about 56 mm

wide by 82 mm long (table 3), with a fresh egg

mass of about 140 to 144 g (Bromley and Jarvis

1993, Crouse et al. 1997). They are laid at the

rate of one per day (Bromley 1976).

Clutch size—Mean annual clutch size has ranged

from a low of 3.6 in 1971 to a high of 5.8 in 1965

(table 8), with individual clutches ranging from 2

to 8 eggs. Typically, low mean clutch size is observed in phenologically late springs (e.g., 1964,

1971, and 1972), and high mean clutch size occurs in early springs (e.g., 1959, 1979).

Egg success—Bromley (1976) compared the fate

of eggs in Trainer’s (1959) study (n = 1,162 eggs)

to results from 1974 (n = 283) and 1975 (n =

1,036). Hatching success of eggs was 0.80 in

1959, 0.67 in 1974, and 0.28 in 1975. Seven percent, 17.2 percent, and 62.3 percent of the eggs

were destroyed by predators in the 3 years, respectively. Of the remaining eggs in 1959 (206)

and in 1975 (100), 10.2 percent and 30 percent

were deserted, 30.1 percent and 0 percent were

flooded, 40.8 percent and 16 percent were dead

embryos, 3.4 percent and 10 percent were dead in

pipped eggs, 4.4 percent and 7 percent were infertile, and 11.2 percent and 37 percent were of unknown fate. An insufficient sample was obtained

in 1974. Hansen (1961) demonstrated that most

of the egg failure in the 1959 study was caused

by flooding during the high spring tides, a phenomenon not observed in the mid-1970s after the

1964 earthquake (Bromley 1976). Beginning in

1982, investigators began to classify the cause of

nest destruction based on published characteristics of depredation and locally acquired experience (Campbell 1990a, 1990b). Whereas nest

destruction during early studies was largely due

to avian predators (Bromley 1976, Trainer 1959),

much of the depredation during the 1980s was

attributed to large mammalian predators, primarily brown bears (Ursus arctos) and coyotes (Canis latrans). Subsequently, colonization of the

nesting area by beaver (Castor canadensis) in the

late 1980s combined with record levels of precipitation resulted in much of the area being

flooded, causing wetter habitat in general

(Campbell 1992b; Campbell et al. 1988, 1992)

and increased egg loss due to flooding (Campbell

and Rothe 1989, Campbell et al. 1988), a phenomenon not experienced since the earthquake.

Renesting—Investigators have long suspected

that renesting occurred in dusky geese, based on

different ages of broods observed late in the season (Olson 1953, 1954a) and distribution of nest

initiation dates (Bromley 1976; Campbell and

Rothe 1989; Campbell et al. 1987, 1988; Grand

et al. 1998). Evidence of renesting became

stronger with records of several second nests in

the same bowls as earlier nests that had been destroyed (Campbell and Rothe 1989), and finally

with the collection of five females in 1997 from

relatively late-initiated nests, for which examination of ovarian condition provided certainty that

at least four of the five were renesting (Grand

and Anthony 1997). Grand et al. (1998) have

attempted to model the extent of renesting based

on nesting data during 1997 and 1998 (fig. 4).

Nest success—Many investigators have determined annual nest success from 1954 to the

present (table 9), ranging from a high of 97 percent in 1966 to a low of 4 percent in 1993. Although Mayfield-type nest success (Mayfield

1975) was not calculated until 1997 (Grand et

al. 1998), destroyed nests were easily detected, at
24

Table 9—Fate of dusky Canada goose nests on the Copper River Delta, 1959-1998

Fate Type of destruction

Year n Successful Destroyed Abandoned Unknown Mammal Avian Flooded Unknown

– – – – – – – – – Percent – – – – – – – – – – – – – – – – Percent – – – – – – –

1959a 1,162 79.6 6.0 1.8 2.0 0.0 11.4 88.6 0.0

1964b 102 82.4 9.8 7.8 — — — — —

1965b 221 62.9 30.3 6.8 — — — — —

1966b 100 97.0 0 3.0 — — — — —

1968b 38 86.8 13.2 0 — — — — —

1970b 186 88.2 8.6 3.2 — — — — —

1971b 100 76.0 24.0 0 — — — — —

1972b 116 81.0 19.0 0 — — — — —

1974c 81 82.7 14.8 2.5 — — — — —

1975c 215 31.6 64.6 3.7 — — — — —

1977d 229 79.0 — — — — — — —

1978d 390 56.2 — — — — — — —

1979d 409 18.2 — — — — — — —

1982e 158 49.2 49.0 1.8 — 45.0 33.8 0 21.8

1983e 162 51.9 36.5 6.0 8.0 64.8 5.6 0 29.6

1984e 161 75.8 14.9 3.1 6.2 62.4 37.6 0 4.0

1985e 258 7.0 81.0 1.9 10.0 78.8 18.4 0 2.8

1986e 201 11.4 67.2 9.0 12.5j 83.7 5.2 0 11.1

1987e 213 23.9 61.0 14.1 1.0 45.6 47.3 7.0 .2

1988e 110 17.3 61.8 3.6 17.3j 53.3 40.0 6.7 .1

1989e 94 4.3 76.6 3.2 15.9j 54.1 45.8 0 .1

1990e 88 44.3 34.1 5.7 15.9j 15.0 85.0 0 0

1991f 91 31.9 35.2 6.6 26.4j 7.2 92.9 0 0

1992g 96 40.6 28.1 7.3 24.0j 33.3 51.9 0 14.8

1993h 100 4.0 68.0 3.0 25.0j 2.9 7.4 0 89.7

1994h 205 4.9 79.0 0 16.1j ——— —

1995h 106 12.3 84.9 2.8 0 56.7 8.9 0 34.4

1998i 81 14.8 71.6 8.6 4.9j ——— —

a

 Trainer 1959; egg success rather than nests.

b

 Timm and Havens 1973.

cBromley 1976.

dBromley unpubl. data.

eCampbell and Rothe 1990.

f

 Campbell 1991c.

g

 Campbell et al. 1992.

h

 Crouse et al. 1997.

i Youkey 1998.

j

 Nests still active at last visit: 1986—9%; 1988—17.3%; 1989 and 1990—unknown; 1991—23.1%; 1992— 22%;

1993—12%; 1994—8%; 1998—4.9%.
25

least until recent times, and were included in the

apparent nest success estimates, alleviating much

of the inherent bias estimating true nest success

rates. Clearly, nest success was much higher during the 1950s through the early 1970s than it has

been since, and thus an overall declining trend is

reflected (fig. 5). Note that in several years, nest

success estimates are minimums, because lateinitiated nests that typically are more successful

than early-initiated nests were not followed to

completion. Nevertheless, because nest success

has been so low, net productivity of adults has

declined over time.

The high degree of renesting in the 1980s and

1990s (Campbell and Rothe 1989; Campbell

et al. 1987, 1988; Crouse 1995; Grand and

Anthony 1997; Grand et al. 1998) may have mitigated, to some degree, the lower success of individual females, particularly because nest success

was higher in late-initiated nests compared to

earlier ones in some years. Bromley (1976) and

Bromley et al. (1995) found that most depredations on Canada goose nests occur during the

early stages of nesting. Although relatively low in

absolute numbers, renests and late-initiated nests

have higher success than do early nests.

Before the 1964 earthquake, nest loss was caused

primarily by tidal flooding during spring and depredation by avian predators (Hansen 1961,

Shepherd 1967, Trainer 1959), but the rate of nest

loss was low. Dusky nests were apparently quite

robust to flooding, and eggs could survive some

degree of immersion in water (Hansen 1961).

Immediately after the earthquake, mammalian

predators appeared to be more abundant on the

CRD than they had been earlier, and rates of nest

loss to predators increased (Shepherd 1966). Nest

success has been highly variable thereafter, with a

long-term declining trend to the present (fig. 5).

Bromley (1976) observed a close relation between annual production of young and annual

spring conditions—reflected by the amount of

snow on the ground on 1 May—and monthly

deviations from long-term, normal temperature

and precipitation. He estimated that spring conditions accounted for 80 percent of the variation in

percentage of young in the population from 1971

through 1975. Campbell (1990b) conducted a

similar investigation for 1982-86 and found that

weather continued to play a significant role in

affecting annual production. He concluded that

the relation operated via habitat availability; during late springs, preferred nesting habitats are

unavailable because of persistent snow, thereby

resulting in greater use of open drainage levees

that are frequented by nest predators.

Brood survival to fledge—Beginning in 1971

(table 10), the proportion of young in the population was estimated annually by an aerial survey

conducted when the young were about two-thirds

grown (Timm 1972b). Thus, to some extent, a

comparison of nest success with the proportion

of young in the population observed later in the

season yielded a rough index to gosling survival.

This estimate is necessarily crude because it

does not account for variables such as the proportion of adult birds that are breeders versus

nonbreeders each year. During most years, when

nest success was high, the proportion of young

seen on the production survey was high and vice

versa, although there were exceptions. In 1988

and 1991, there were more young than could be

expected from the very low nest success observed, thereby indicating that brood survival,

or perhaps undetected renesting, was higher than

usual despite low nest success recorded on surveys. In 1972, 1975, 1983, and 1984, there were

far fewer young than expected given high nest

success (tables 9 and 10), thereby indicating the

likelihood of very poor brood/gosling survival in

those years (Campbell and Rothe 1985, Cornely

et al. 1985).

Studies of brood survival by using radio-marked

goslings were initiated in 1997 (Grand and

Anthony 1997). Preliminary results from their

first 2 years of study indicate relatively low

gosling survival caused by high rates of depredation (Grand et al. 1998).

Production—Production estimates for duskys on

the nesting grounds, in the form of percentage

of young in the population [(no. young/(no. adults

+ no. young)) x 100], have been conducted annually since 1971 by the Alaska Department of Fish
26

Figure 5—Nest success rates of dusky Canada geese on the Copper River Delta,

Alaska, 1954-2000.

Table 10—Percentage of young observed among

dusky Canada geese on the Copper River Delta,

Alaska, from July aerial surveys, 1971-2002

Year Young Year Young

Percent Percent

1971 16.2 1987 9.8

1972 10.6 1988 22.8

1973 36.0 1989 8.6

1974 51.4 1990 23.5

1975 17.9 1991 21.5

1976 24.2 1992 23.1

1977 44.3 1993 5.0

1978 24.8 1994 5.7

1979 16.0 1995 3.9

1980 23.7 1996 21.7

1981 17.9 1997 10.5

1982 23.7 1998 11.7

1983 15.0 1999 14.7

1984 18.3 2000 24.1

1985 3.7 2001 25.4

1986 10.7 2002 30.5
27

and Game (Timm 1972b). Initial observers noticed that during surveys on which Beaver aircraft

were used in low and slow flight, identification of

pure adult flocks and mixed flocks of both adults

and young could be discriminated. They recommended that for mixed flocks one observer count

young and another count adults. Furthermore, to

account for their inability to detect all young in

brood flocks, they arbitrarily assumed a visibility

rate of 50 percent, and thus doubled the number

of young to derive a final estimate of the percentage of young in the population. This method was

used through 1984 and yielded estimates that

were supported by independent estimates from

age ratios in the harvest, adjusted for differential

vulnerability to hunting (Timm et al. 1979). Also,

for 1975 through 1984, trends (decreasing or increasing) between years for age ratios in the harvest on refuges in Oregon (Jarvis and Cornely

1988) were entirely consistent with estimates of

percentage of young in the population on the

breeding ground (Campbell 1984, Campbell and

Rothe 1985, Campbell and Timm 1983, Timm

1982, Timm and Sellers 1979, Timm et al. 1979).

From 1985 through 1991, a Cessna 185 was used

with a pilot and two observers: one observer in

the front assisted with spotting and navigation,

then counted adults and took aerial oblique photographs of flocks (1986-88), and the observer

in the rear counted young and recorded data

(Campbell and Rothe 1986). Logistical problems

prevented visibility-corrected estimates in 1985

and 1989-91 (Campbell and Rothe 1986, 1990),

but weighted regressions were used to estimate

both numbers of adults and young in 1986-88

(Campbell and Rothe 1989; Campbell et al.

1987, 1988) (table 10). From 1992 to the present

(Petrula 2001, 2002; Rothe 1993, 1994, 1995,

1996, 1997, 1998, 1999; Rothe and Petrula 2000),

a Robinson 22 helicopter was used, wherein the

pilot and one observer flew 4.8 to 6.0 hours of

survey each year. Total numbers of adults and

young observed, and percentage of young were

reported. Recorded numbers of young were

doubled in all cases, as with original counts

(Timm 1972b). During the period 1971 through

1984, production ranged from 10.6 to 51.4 percent young and averaged 24 percent young (table

10). Since 1985, the annual proportions of young

have been variable (3.7 to 30.5) averaging only

15 percent young, and production has been below

10 percent in 6 of the past 18 years.

Nest densities and nearest neighbors—Using

100 random plots of 2.6 ha, Courtright (in Olson

1954c) determined a nest density of 0.03 to 0.04

nests per ha on a 225-km2

 study area between

Copper (Alaganik) Slough and Kokanhenic

Channel in 1954. In a high-density area of about

4.1 km2

, Trainer (1959) found 0.42 nests per ha.

These studies reflect a relatively low density of

nests before the 1964 earthquake.

Shepherd et al. (1967) established 15 random 2-

ha plots, in which they located 13 nests in 1966

(0.4 per ha). Seven of these plots hosted 27 nests

(1.9 per ha) in 1970 (McKnight 1971) and 20

nests (1.4 per ha) in 1972 (Timm and Havens

1973). Bromley (1976) found, in 20 random plots

of 2 ha, a mean density of 0.6 nests per ha in

1974, and in larger nonrandom plots spanning

low-, medium-, and high-density strata, densities

of 0.3 to 1.3 nests per ha in 1975. One of these

large plots, overlapping with part of Trainer’s

(1959) study area, had a density of 0.8 nests per

ha in 1975. Studies in the late 1960s through the

1970s reflected continually increasing densities

of nests on the CRD.

Alaska Department of Fish and Game biologists

continued searching the eight sample plots established by Bromley (1976) through 1992 (table

11), adding a 9th plot in 1981 and a 10th in 1983;

the size of the plots ranged from 0.23 to 0.88 km2

and totaled 4.3 km2. Nest densities remained

stable at about 0.7 nests per ha through 1980,

dropped to about 0.5 nests per ha throughout the

1980s, then declined further to 0.4 nests per ha by

the early 1990s (table 11). Whereas consistent

plot surveys were intended to illustrate changes

in nest density between 1975 and 1992, habitat

succession on the plots may have caused redistribution of geese, thereby obscuring actual trends

in nest densities. The high nest densities characteristic of the coastal stratum plummeted between

the mid-1970s and the early 1990s (fig. 6a),

whereas densities in the middle and inland strata
28

remained fairly stable overall (fig. 6d) but actually increased in some plots (e.g., plot 7, fig. 6c

and plot 6, fig. 6b). In 1992, the Pacific Flyway

Subcommittee on the Dusky Canada Goose recommended discontinuing these searches because

the data were not being used in management decisions. Instead, the subcommittee recommended a

program of nest searches of random plots

throughout the CRD, to be conducted every 3

years, to provide nest-density data that might be

useful in population estimation, similar to the

method used in western Alaska (Stehn 1991). The

new nest survey regime, implemented by the

USDA Forest Service, Cordova Ranger District,

was also intended to provide occasional measures

of nest success in relation to types of nest predators and trends in habitat use by dusky geese

across the CRD.

Thus, random plots were established within a

212-km2

 extensive study area; average nest densities were 22.0 ± 4.3 per km2 (0.2 per ha) from

1993 through 1995 (Crouse 1994b, 1995; Crouse

et al. 1995). In 1998, Youkey (1998) repeated the

survey and found 17.7 nests per km2

 (0.18 nests

per ha—uncorrected for detection rates and lateinitiated nests) during the early search (i.e., probably did not include later renests). They also

examined nest detection rates by next-day repeat

searches of plots with independent field crews,

and derived a detection rate of 83.2 percent ± 0.4

percent (95 percent CI) for nests on plots. Thus, a

corrected mean density would be about 0.21 nests

per ha. In an area overlapping with Trainer (1959)

and Bromley (1976), Grand and Anthony (1997)

found 412 nests in 13.5 km2

 (0.31 per ha) within

Table 11—Dusky Canada goose nest densities on standardized study plots, Copper River

Delta, Alaska, 1975-1991

Plot

12 3 4 5 67 8 All plots

– – – – – – – – – – – Area (km2) – – – – – – – – – – – – km2

0.23 0.36 0.23 0.61 0.87 0.28 0.20 0.49 3.27

Year – – – – – – – – – – – – Nests/km2

 – – – – – – – – – – – – km2 Nests/km2

1975 1.13 1.12 0.70 0.64 0.68 0.50 0.16 298.9 0.70

1976 1.04 .70 .66 .53 .55 .10 263.1 .60

1977 1.26 .78 .70 .52 .64 0.50 .60 .31 326.9 .66

1978 1.52 1.03 .57 .48 .63 .50 257.9 .79

1979 .48 .53 .70 .44 .54 .79 257.9 .58

1980 .87 .61 .54 .53 206.9 .64

1981 .35 .8 .17 .33 .16 .21 .20 277.9 .22

1982 .56 .33 .48 .48 .55 .79 .25 .22 326.9 .46

1983 .74 .42 .39 .31 .43 .68 .45 .33 326.9 .47

1984 .43 .20 .52 .41 .43 .93 .30 .29 326.9 .44

1985 .91 .28 .61 .30 .41 .75 .40 .29 326.9 .49

1986 .82 .39 .43 .38 .50 1.11 .25 .41 326.9 .54

1987 .52 .47 .35 .34 .50 .86 .30 277.9 .48

1988 .61 .42 .35 1.04 .50 129.9 .58

1989 .48 .39 .30 .79 .70 129.9 .53

1990 .39 .22 .39 .57 .55 129.9 .43

1991 .13 .25 .30 .71 .65 129.9 .41

Data sources: Original data from Bromley 1976, Bromley unpubl. data, and Alaska Department of Fish and Game

annual reports: Campbell 1984, 1991c; Campbell and Rothe 1985, 1986, 1989, 1990; Campbell and Timm 1983;

Campbell et al. 1987, 1988.
29

Figure 6—Nest densities of dusky Canada geese on sample plots on the Copper River Delta, Alaska, 1975 through 1991.
30

the high-density stratum in 1997. Based on these

studies, nest densities apparently peaked in 1978

and declined thereafter to levels similar to those

measured during the 1950s.

Little work has been conducted on the eastern

CRD; however, Mickelson et al. (1980) sampled

1.56 km2

 of belt transects on a 91.5-km2 study

area there and estimated a mean density of 1.9

nests per km2

 (0.02 per ha) in 1978 and 1979.

Trainer (1959) found that nearest nesting neighbors were at least 91 m apart, and most were at

least 183 m. In one of Bromley’s (1976) plots in

1975, nearest neighbors averaged 51 m (n = 40

nests, sd = 15, range = 31 to 88 m), which was

consistent with nest densities that were higher in

the 1970s than in the 1950s.

In summary, major efforts using large samples

of random plots to determine nest densities were

conducted in 1954, 1993 through 1995, and in

1998, and consistent surveys were conducted on

nonrandom plots from 1975 through 1992. Although not all estimates are comparable, it appears that nest densities increased from a low in

the 1950s to a peak in the mid-1970s, then declined to a level similar to that of the 1950s. Random sample plots yield the best estimates of

representative nest densities throughout the CRD.

These surveys will be continued every 3 years

(Pacific Flyway Council 1997). However, the

tendency for duskys to renest at higher rates in

years with late springs, associated with high rates

of nest loss early in the season, makes it problematic to interpret nest densities over time as an

index to the density of breeding pairs (e.g.,

Crouse et al. 1997, Grand et al. 1998).

Molt and dispersal—Olson (1953, 1954a) observed the first flightless duskys of the year on 4

July in 1953 and 5-10 July in 1954. He concluded

that most adult geese were flightless by 20-27

July 1953 and by 19 July 1954, and that one-third

could fly by 4-5 August each year. One-half to

three-quarters could fly by 10 August 1953, and

three-quarters were flight capable by 12 August

1954. Trainer (1959) reported the first flightless

geese of 1959 on 6 July, with most geese molting

by 15 July. Bromley (1976) reported flightless

birds by the second week of July 1974 and 1975,

and estimated that 95 percent of adult geese were

capable of flight by mid-August. Although

Mickelson et al. (1980) saw few geese during the

breeding season on the eastern CRD, geese were

observed using the area for molting in August,

with at least 120 of 500 to 700 birds still flightless on 9 August. Grand (1997) observed premolt

movements of two nest-trapped and radio-marked

females out of high-density nesting areas near

Alaganik Slough. These two birds lost or abandoned broods and moved south and east up to 105

km to areas near the Martin and Bering Rivers,

and Bering Glacier.

Beginning in mid-August, and by the end of

August, redistribution occurs in which geese

disperse into areas not used since early spring,

such as onto the upper CRD and the eastern

CRD. Crowley (1999a) observed 110 Canada

geese, including five neck-collared duskys, on

Hinchinbrook Island in PWS in September 1996.

Mickelson et al. (1980) interpreted a movement

of large numbers of duskys onto the eastern CRD

throughout August as a postmolt dispersal onto

fall staging habitat.

Migration

Duskys begin an eastward shift in mid-August

through early September, after which the majority

of the population has departed from the western

CRD; remaining geese, an estimated 2,000 to

3,000 in both 1978 and 1979 on the eastern CRD

(Hawkings 1982), stage from early to at least

mid-October before the final exodus (Crouse

1994a, Hawkings 1982, Mickelson et al. 1980).

Some birds move southeast to stage on the

Yakutat Forelands. Petersen et al. (1981) reported

two peaks of duskys staging there, one during 15-

25 August and another during 4-10 October 1980.

Hawkings (1982) examined weather conditions

associated with visible bird migration through the

eastern CRD during late fall and concluded that

migration was associated with the most favorable

upper air winds at Anchorage and surface winds

at Cordova, southwest winds in the upper air and

at the surface, and rapidly increasing atmospheric

pressure.
31

Based on leg band returns, Hansen (1960, 1962)

concluded that duskys had left the CRD by 15

October, and he suggested that the birds migrate

offshore stopping at relatively few accessible

places en route south. Petersen et al. (1981) reported that far fewer duskys were observed

during fall migration at the Yakutat Forelands,

Alaska, than during spring. Hansen (1960) found

the first band returns from Vancouver Island

about 20 October. Observations in the QCI indicate that for the years 1982, 1986, 1988, and

1990, when consistent records were kept, goose

numbers tended to increase during early to mid

October each year (Hearne 1999). Kebbe (1958),

examining the date of band returns in the

Willamette Valley for the period 1951-57, concluded that although occasional flocks arrived as

early as mid-October, average peak arrival was

mid-November. Looking at band returns during

consecutive 10-day periods, Chapman et al.

(1969) described the chronology of fall migration from Alaska to Oregon. Peak arrival dates

in the Willamette Valley were early to mid

November. Zeillemaker (1973) noted that duskys

began arriving at Baskett Slough National Wildlife Refuge (NWR) in Oregon on 25 September

1971-73, with the first duskys at William L.

Finley NWR on 1 October 1973. Numbers

built rapidly through 2 November of that year.

Naughton (1993) reported the first duskys at

William L. Finley NWR on 12 October in both

1985 and 1986.

Rodgers (in Timm 1972b) noted that duskys departed William L. Finley NWR on 14 April 1972.

On 23 April of the same year, Timm (1972a) with

B. Wood of Alaska Department of Fish and

Game, saw many flocks of what appeared to be

duskys at Ketchikan, Alaska, heading north.

Zeillemaker (1974) observed duskys departing

from Willamette Valley refuges 14-19 April 1973

and 19-21 April 1974, noting of the latter that it

was late compared to the average departure date

of 14 April. Spring departures of duskys from

wintering sites also were observed on 18-19 April

1975 (Rodgers 1975) and 15-21 April 1976

(Annear 1976), and Naughton (1993) reported the

last departures from William L. Finley NWR by

15 April each year during the mid-1980s. Duskys

migrated by the Yakutat Forelands during 9-19

April 1980 (Petersen et al. 1981). On the eastern

CRD, duskys migrated through in small flocks

during mid to late April, with numbers declining

rapidly after 17 April 1979; spring migration was

much briefer and more concentrated than fall

migration (Hawkings 1982). Visible bird migration through the eastern CRD area coincided with

high pressure systems over the CRD bringing

southwest surface winds and northwest upper air

winds, high pressure, clear skies, and large diurnal range in temperature (Hawkings 1982).

Bromley (1984) recorded one family group of

five duskys, including three uniquely neck-collared individuals that migrated from William L.

Finley NWR, Oregon, to the CRD in a maximum

of 4 days; however, he noted the average time for

spring migration was about 11 days.

Wintering

Before the establishment of federal refuges, hunt

clubs strongly influenced the distribution and

harvest of wintering duskys in Oregon (Chapman

et al. 1969, Hansen 1962). Chapman et al. (1969)

reported that in the absence of a public refuge

program, the harvest could have been much

greater had the hunt clubs not provided refuge

and regulation of the take. By the late 1960s,

however, refuges had assumed the role of providing food and haven for geese (Chapman et al.

1969, Hansen 1968).

Duskys arrive in the LCR and Willamette Valley

before the arrival of the most abundant races,

cackling and Taverner’s Canada geese (Jarvis and

Bromley 1998, Simpson and Jarvis 1979). The

relative abundance of duskys is consistently highest at William L. Finley NWR, particularly after

the hunting season is over (Simpson and Jarvis

op. cit.). Sheaffer (1993) studied subflock behavior based on 947 individually marked duskys and

concluded that those wintering at the southern

and northern extremes of their wintering range,

near William L. Finley NWR and Sauvie Island

Wildlife Area, respectively, had the highest wintering site fidelity. Over 65 percent of these geese

were not observed outside of their respective

wintering areas. The marked geese formed 9 to
32

10 indistinct clusters of 191 to 206 groups averaging 2.8 marked birds per group each for the 3

years of study, and groups had the same affiliations during both harvest and nonharvest periods

(Sheaffer 1993).

Duskys typically select smaller fields for feeding than do other sympatric races of wintering

Canada geese (Havel and Jarvis 1988, Simpson

and Jarvis 1979). Based on research at Sauvie

Island, Oregon, where duskys commonly winter

in mixed aggregations with other subspecies,

Havel and Jarvis (1988) concluded that duskys

are segregated during commuting flights but

mixed during feeding, and that they select fields

with fewer geese to feed in and approach lower

and circle less before landing than do other subspecies. These characteristics result in higher

vulnerability of duskys to harvest (Havel and

Jarvis 1988, Jarvis and Cornely 1988, Simpson

and Jarvis 1979).

Food Habits

Reproduction—Food habits during nesting,

brood rearing, and molt are poorly known. Dusky

geese feed on tidal mudflats in early spring and

during brood rearing and molt. They use spring

melt pools in horsetail (Equisetum spp.) and

sedge (Carex spp.) stands during the early spring

melt, and they have been observed feeding on

early sedge and horsetail shoots, and unfurled

leaves of prostrate willow (Salix arctica Pall.)

late in the melt (Bromley pers. obs.). During late

incubation, the esophageal and proventricular

contents of 12 adult female geese on the CRD

contained sedge leaves and seeds, horsetail, prostrate willow leaves, and vetch (Lathyrus spp.)

stems and leaves (Bromley 1984).

Migration—Duskys consumed at least 26 species of 13 families of plants on the eastern CRD

during September and October (Hawkings 1982).

In particular, 15 species of Cyperaceae,

Gramineae, Juncaginaceae, and Juncaceae, together with horsetail (Equisetum arvense L.),

accounted for 87 percent of the total volume of

the diet (Hawkings 1982). Leaves were the most

important component by volume overall; however, seeds and roots increased in importance as

fall advanced. In freshwater habitat on the eastern

CRD, geese selected horsetail, Lyngbye’s sedge

(C. lyngbyei Hornem.), Nootka alkali grass

(Puccinellia nutkaensis (Presl) Fern. & Weath.),

and plantain (Plantago maritima L.). In salt

marsh, they selected arrow grass (Triglochin

palustris L.), horsetail, bent grass (Agrostis spp.),

and rush (Juncus alpinus Vill.) (Hawkings 1982).

Wintering—Although there have been no studies

on diet of duskys during winter, it is commonly

understood that they rely largely on agricultural

crops (e.g., Clark and Jarvis 1978, Pacific Flyway

Council 1998). Federal and state refuge management directed toward providing food crops is

likely a good reflection of the favored winter

foods of duskys. On William L. Finley NWR

during the mid-1980s, crops provided included

about 1,000 acres of perennial ryegrass (Lolium

perenne L.), 500 to 700 acres of annual ryegrass

(L. multiflorum Lam.), 320 acres of pasture

(grasses and forbs), 200 acres of tall fescue

(Festuca arundinacea Schreb.), and 35 acres of

winter wheat; there were 185 acres of corn during

one winter (Naughton 1993). During this period,

Canada geese, of which about half were duskys,

tended to use annual and perennial ryegrass most

extensively, particularly during early and late

winter; tall fescue and pasture were predominantly used during midwinter, with pasture being

used significantly less than any other forage type

(Naughton 1993). Crop plants on the refuge decreased in height and cover from November

through January, then increased from February

until the geese departed; numbers of geese on the

refuge followed a similar pattern (Naughton

1993). Naughton (1993) observed a relation between goose use of fields and food quality during

spring 1986, but not during the following spring.

She noted, however, that the average quality and

quantity of these forage crops are high. Thus,

other factors such as weather and security may

influence patterns of field selection for foraging.

Crops most commonly provided on federal and

state lands in total, in descending order of acreage, include pasture grasses, moist soil vegetation

(Fredrickson and Taylor 1982), annual ryegrass,

perennial ryegrass, fescue, Sudan grass/millet
33

(Sorghum bicolor (L.) Moench ssp. drummondii

(Nees ex steud.) deWet and Harlan), clover, and

corn (Pacific Flyway Council 1998). On the

Saanich Peninsula of Vancouver Island, British

Columbia, Macgregor (1993) observed duskys

feeding on waste carrots and pasture.

Habitat

Breeding—Almost the entire population of

dusky Canada geese nests on the CRD in southcentral Alaska. The Copper River, originating at

the Copper Glacier on the border between Alaska

and Yukon, flows 179 km to the Gulf of Alaska

(Kruger and Tyler 1995). There, the river, in concert with much smaller rivers from several adjacent glaciers (Scott, Sheridan, and Sherman on

the west, and Bering on the east), deposits huge

silt loads in the relatively still waters of the Gulf

of Alaska. The combined effect of the glaciers

and rivers yields a characteristic pattern from

inland to the sea, of “...kettle-kame topography,

moraines, outwash plains or flood plains, deltaic

deposits and dune-dominated landscapes fronting

the ocean” (Boggs 2000), with the upper landscapes consisting of glacial outwash gravel deposits. Although this general pattern persists, the

finer terrestrial and aquatic features of the delta

are constantly experiencing dynamic change, as

they are carved and molded by glacial, riverine,

tidal, and tectonic forces.

The Chugach Mountains shielding the delta from

the cold interior air masses to the north, and the

marine environment to the south combine to

develop a maritime climate with mild, wet summers and cool, wet winters. Precipitation is high,

averaging 218 cm midway across the piedmont,

and an average of 262 days per year are cloudy

(Searby 1969). Boggs (2000) reports that “mean

monthly temperatures at sea-level range from -4

°C in January to 14 °C in July.”

Upon arrival in early spring and when extensive

snow cover remains, duskys concentrate for staging and foraging in snow- and ice-free intertidal

zones in Orca Inlet, such as in Hartney Bay, and

early snow-free habitats along the Copper River

Highway through the upper delta. These habitats

were not greatly affected by the earthquake, and

this pattern persists today. As snowmelt progresses on the outer delta, geese gradually move

out to set up territories in their nesting habitats

(Bromley pers. obs.).

In the late 1950s and early 1960s, nesting geese

on the delta concentrated in an outer 4- to 6-kmwide zone dominated by extensive sedge flats

with slough levees vegetated by forbs, grass, and

a low shrub, sweet gale (Myrica gale L.) (Nelson

1953; Olson 1954c; Trainer 1959, 1967; Trainer

and Shepherd in Hansen 1961). Restricted in their

use of different habitats by frequent, high, inundating tides, duskys nested largely within the

grass-forb habitat along the raised levees bordering the tidal channels (97 percent of nests in 1959

(Trainer 1959)). The grass-forb habitat occasionally experienced tidal inundation during the nesting season (Hansen 1961). As this zone integrated

with inland habitat dominated by alder (Alnus

spp.) and willow (Salix spp.), nest densities of

geese decreased (Shepherd 1961; Trainer 1959,

1967). Nests were highly successful because

there was little loss to depredation (Courtright in

Olson 1954a, Trainer 1959).

Dramatically accelerated successional changes

have occurred because of the uplift by the 1964

earthquake. Essentially all preearthquake intertidal habitats are no longer flooded by tides

(Potyondy et al.1975; Shepherd 1966; Thilenius

1990a,1990b). Freedom from tidal influence led

to desalinization of soils, a process enhanced and

accelerated by high annual rainfall (Crow 1971,

Shepherd et al. 1968), and an increased rate of

community succession, including colonization of

all habitats by the shrubs sweet gale, willow, and

alder (Shepherd et al. 1967, Thilenius 1995).

Salt-tolerant plants have been replaced with other

species often of less nutritional value to geese

(Crow 1971). Shrubs became established quickly

in previously intertidal basins and levees, but less

quickly on the higher levees, possibly because of

interspecific plant competition in those habitats

(Crow 1971). Today, the sharp delineation of

ecotones typical during preearthquake times

(Crow 1968) is no longer obvious, and habitats

have considerably more closed canopies than

previously (Thilenius 1995). The new salt marsh
34

zone, developing about 15 km seaward, is relatively small and expanding slowly with the interaction of colonizing sedges and silt trapping.

Remaining habitats are no longer saline, and although they still often host extensive swards of

Lyngbye’s sedge, they have become colonized

and are visually dominated by shrubs (sweet gale,

willow, and alder) (Thilenius 1995).

Despite the great changes, geese have continued

to occupy the same zone on the outer delta as

previously described by Campbell (1988), Trainer

(1959), Shepherd (1961), and Hansen (1961).

Within 3 years of the earthquake, however, geese

began increasing their use of the sedge meadow

habitat for nesting (Shepherd et al. 1968). Geese

were no longer restricted to the levees for nesting

because tides no longer flooded meadow habitat.

The increase in use of sedge meadow for nesting

continued through 1975 when 20 percent of their

nests were in this habitat (Bromley 1976), and

during 1982-86 when an average of 40 percent

were in sedge meadow (Campbell 1990b). The

greater extent of shrubs in all communities, but

particularly in sedge basins, did not deter geese

from nesting there. By 1975, 23 percent of nests

were in low shrub habitat (Bromley 1976), and

during 1982-86 an average of 46 percent of nests

were in low and tall shrub habitat (Campbell

1990b). Geese did not stop using sedge meadow

and grass-forb nesting habitat even with the prolific colonization of those habitats by low and tall

shrubs.

During the late 1980s, beavers colonized the nesting area in great abundance, damming up old

tidal channels and causing substantial flooding in

habitats that were relatively dry in the 1970s

(Campbell 1992b, Campbell and Rothe 1989,

Campbell et al. 1988). Although this caused some

nests to be flooded during the early years of this

phenomenon when spring precipitation was much

above normal, the extensive new impoundments

may have resulted in a decrease in nest predation

by large mammalian predators (Campbell 1992b,

Campbell et al. 1988). In recent years, no nests

have been lost to flooding (Crouse et al. 1995).

Three studies of nest habitat availability and use

have been conducted on the CRD. During the

mid-1970s, nesting geese preferred low shrub and

grass-forb or levee habitats, while tending to

avoid the sedge habitat (Bromley 1976). A decade

later, nesting geese still preferred low shrub habitat, and also the new tall shrub habitat, while

selecting against the levee habitat; they used

sedge meadow habitat in proportion to its availability (Campbell 1990b). Both investigators

concluded that nesting cover was an important

factor for nesting geese, and Campbell (1990b)

found that annual variation in nesting habitat

selection was accounted for by spring habitat

conditions and phenology. During late springs,

snowmelt in shrub habitats is retarded relative to

that in open habitats, and thus shrub habitats are

relatively less available to nesting geese. During

1993-95, Crouse et al. (1997) reported findings

similar to Bromley (1976), with geese using willow and sweet gale community types in a greater

proportion than their availability, and avoiding

sedge community types for nesting. Further, they

demonstrated that geese used peninsulas and new

marsh sites in greater proportions than their availability, and avoided levees and interlevee basins.

Both Crouse et al. (1997) and Bromley (1976)

concluded that geese preferred low shrub cover at

nest sites. Bromley (1976) suggested that the

geese might be selecting for good visibility from

nests, and ease of sudden escape if attacked by

predators. Campbell (1990b) and Crouse et al.

(1997) found that during 1982-86 and 1993-95,

nests in all community types were equally susceptible to depredation.

New tidal marsh habitat has been slow to develop

on previously subtidal land exposed by the earthquake (Kempka et al. 1995). Slopes of the submarine and tidal portions of the delta increased from

an estimated 3 to 4.5° preearthquake to 6° postearthquake (Reimnitz 1972) so that the effective

area exposed for development of beneficial nesting habitat for geese in the short term is small.

Shepherd (1966) predicted that the area would

not likely be over 50 km2

. Boggs (2000), however, reviewed the processes involved and noted

that conditions for the development of new tidal
35

marsh are currently excellent. Pioneer species

such as dwarf alkali grass (Puccinellia pumila

(Vasey) Hitchc.) and Lyngbye’s sedge are now

becoming established on the tideflats and will

result in accretion and stabilization, causing the

marsh front to advance seaward. In addition, the

delta apparently has experienced a cycle of sudden uplift and gradual subsidence at least four

times in the past. Because of the uplift, two buried forest horizons were revealed (Reimnitz

1972); subsequently two others were located, and

carbon-14 aging of the material has indicated an

interval of 600 to 950 years between earthquake

events that resulted in sudden uplifts with gradual

subsidence of 2 to 7 mm per year (Plafker 1990).

During the 800 years before the 1964 earthquake,

the rate of interseismic subsidence averaged 3 to

5 mm per year, and the longer term (3,000 years)

net vertical change on the CRD has been one of

submergence (i.e., including tectonic subsidence,

eustatic and isostatic sea level rise totaling 4.5 to

6.5 mm per year), rather than uplift (Plafker et al.

1992). Based on these studies, Boggs (2000),

using a long-term perspective, expects that CRD

tidal marshes likely will continue to exist and

even expand over a period of hundreds to thousands of years.

Migration—Little is known of migration habitat

for duskys. Hansen (1962) suggested that geese

migrate offshore, stopping occasionally at the few

accessible places en route. During early September to mid-October staging on the eastern CRD,

geese use first salt marsh habitat, then freshwater

meadow habitat (Crouse 1994a, Hawkings 1982).

Crouse (1994a) surveyed the Copper and Bering

River deltas and concluded that the most important concentration areas during fall were Dan

Bay off Hinchinbrook Island, Egg Island, intertidal habitat off the central western CRD, and

Okalee Spit near Controller Bay. Petersen et al.

(1981) concluded that the Yakutat Forelands,

Alaska, were potentially important staging

habitat for duskys, in particular the Blacksand

and Ahrnklin Rivers during early fall, and the

Dangerous, Italio, and Akwe Rivers during late

fall. Riverine habitats were more important than

estuarine habitats.

Bromley and Jarvis (1993) concluded that about

one-half of the energy for geese spring migration

was derived from lipid reserves, with the remainder met through acquisition of food en route.

Thus, staging areas that are regularly used by

migrating duskys must be important, but they

remain poorly known at this time. Petersen et al.

(1981) suggested geese usually stop for about

1 day on the Yakutat Forelands during spring

migration.

Wintering—The LCR and the Willamette Valley,

characterized by mild, wet climate during winter

and by extensive agriculture, provide ideal habitat

for wintering Canada geese (Chapman et al.

1969, Cornely et al. 1985). Common agricultural

practices, including dairy farming and production

of ryegrass seed (Kimerling and Jackson 1985),

yield high-quality forage with high protein content (Riewe and Mondart 1985, and reviewed in

Jarvis and Bromley 1998). A network of federal

and state waterfowl refuges established in the

mid-1960s provides an additional attraction and

security for wintering geese. On 19 February

1963, the Migratory Bird Conservation Commission authorized the establishment of three national wildlife refuges to be located at traditional

goose concentration areas in the Willamette Valley (USDI Fish and Wildlife Service 1980). In

1964, land acquisition for William L. Finley

NWR (2155 ha) was completed; Baskett Slough

NWR (1009 ha) was established during 1965-67,

and Ankeny NWR (1132 ha) was established

during 1965-71. In addition, Ridgefield NWR

(2060 ha) on the LCR in southwest Washington

was acquired in 1965 to provide wintering habitat

for duskys (Pacific Flyway Council 1998). The

mandate of these valley refuges, under the authority of the Migratory Bird Conservation Act and

the Migratory Bird Hunting Stamp Act, is to provide wintering habitat for dusky Canada geese.

Duskys also use the coastal Oregon Islands

NWR, established for seabird habitat in the mid1960s, near Nestucca, in Tillamook County

(Lowe 1987).

The state of Oregon’s Sauvie Island Wildlife

Area, for which acquisition began in 1947 to preserve and develop habitat for wintering waterfowl
36

and to provide for public hunting, is now over

4800 ha (Oregon Department of Fish and Wildlife, n.d.). The Shillapoo and Vancouver Lake

State Wildlife Areas in southwest Washington

along the Columbia River flood plain encompass

627 ha. Since the establishment of Shillapoo in

1952, the Washington Department of Fish and

Wildlife has been expanding these areas through

acquisitions.

Duskys tend to concentrate in and near federal

and state wildlife refuges in the Willamette Valley and the LCR in Washington and Oregon, with

about 700 wintering near Nestucca on the Oregon

coast (Havel and Jarvis 1988; Lowe 1987, 1999;

Simpson and Jarvis 1979). In particular, the largest proportion of wintering Canada goose flocks

that are duskys consistently occur on and in association with William L. Finley NWR, the southernmost of the valley refuges; the smallest

proportion of duskys occur on Ankeny NWR

(Simpson and Jarvis 1979). Although there are

seasonal differences related to the timing of

spring and fall migration, the proportions of

duskys are consecutively smaller at Sauvie Island

Wildlife Area, Ridgefield NWR, and Willapa Bay

NWR (Atkinson 1992, Havel and Jarvis 1988).

Wintering habitat of geese in British Columbia

remains poorly known. Macgregor (1993) consistently observed wintering duskys using carrot

fields and pasture in the Blenkeinsop Valley of

the Saanich Peninsula on Vancouver Island, and

Hearne (1999) observed duskys using the coastal

marshes of Delkatla Wildlife Sanctuary in the

QCI throughout the winter season.

There is increasing concern about crop depredation by feeding geese in association with rapidly

increasing numbers of Canada geese wintering in

the Willamette Valley and southwest Washington

(Pacific Flyway Council 1998). Clark and Jarvis

(1978) demonstrated that, at grazing intensities

characteristic of the mid-1970s, geese had little to

no detrimental effect on ryegrass crops (8 of 10

fields); in some cases (2 of 10 fields), yields were

greater in grazed fields. Wintering Canada geese,

however, now number about 10 times that of the

1970s, and crop depredation complaints are common. In response, the Pacific Flyway Study Committee and the Canada Goose Agricultural Depredation Working Group is currently implementing

an agricultural depredation control plan to address these concerns (Pacific Flyway Council

1998). This effort is sensitive to the concerns for

conservation of dusky geese.

Population Dynamics

Population Status

The dusky population has been estimated annually in western Oregon since 1947 (Kebbe 1958),

and in Washington and Oregon since 1953

(Hansen 1962); it has fluctuated from lows during

the mid-1950s (~5,000) to highs during the late

1970s (~20,000 to 25,000) and back to lows during the 1990s (~12,000 to 14,000) (fig. 7) (Drut

and Trost 2003, Pacific Flyway Council 1997).

Different methods used to estimate population

size are briefly described below.

Wintering grounds—Kebbe (1958) reported

winter inventories of duskys in western Oregon

for 1947-58 (fig. 7), without giving methods of

counting, but presumably, they were aerial counts

as reported by Hansen (1962). Based on calculations of numbers of geese produced and harvested

from studies by Olson (1953, 1954c) and Trainer

(1959) and compared with wintering ground studies (Kebbe in Hansen 1962), Hansen (1962,

1968) concluded that the best estimates of dusky

numbers were the midwinter aerial survey counts

conducted in Oregon. He noted, however, that

counts did not include Washington and British

Columbia, so he recommended adding 2,000

birds to annual estimates to account for this gap.

Thus, total population estimates from 1953 to

1960 ranged from 7,080 to 16,450 birds. Hansen

(1968: 48) noted that there was no evidence that

this subspecies had ever been abundant.

Photo estimates—Aerial surveys were soon standardized to include the same counties and locales

each year in Oregon and Washington but still

excluded British Columbia; these surveys were

continued through 1975 (fig. 7) with little change

in methods (Jarvis and Rodgers 1976; Rodgers

1973, 1974) (unadjusted for birds wintering in
37

British Columbia). Because of increasing numbers of other races of Canada geese within the

census area, however, methods differed thereafter

(fig. 7). In 1976, because of the influx of other

Canada geese, the midwinter survey of duskys

yielded unrealistically high numbers. Therefore,

an estimate of duskys was made by averaging the

dusky harvest for the past 3 years and subtracting

it from the fall flight estimate provided by the

Alaska Department of Fish and Game (Jarvis

and Rodgers 1976). In winter 1976-77, groundbased surveys were conducted in the Willamette

Valley and LCR to estimate the proportion of

Canada geese that were duskys, and this estimate

(82.9 percent duskys) was applied to the midwinter index of total Canada geese. The 1977-78

midwinter counts of all Canada geese from late

November to early December (48,000) were

much higher than counts in January and February

(31,000), so the practice of using the maximum

winter count was adopted; thus, the estimate was

based on a maximum winter count of 48,000

geese with a composition of 42.5 percent dusky

(Jarvis 1978). This method was continued in

1979 and 1980.

A method to estimate the proportion of duskys

based on aerial photographs was developed in

1979, with the first official implementation in

1981 (Jarvis 1980, Jarvis and Sekora 1981). The

reason for this was threefold: (1) the numbers of

nondusky Canada geese were continuing to grow

in all parts of the duskys’ winter range but in

varying proportions, (2) the overall wintering

Canada goose flock was growing rapidly, and (3)

geese were no longer reliably concentrated in and

near the refuges during censuses in January. The

aerial survey and photography method was used

and refined through 1992 (Cornely and Jarvis

1984, 1985; Cornely et al. 1986; Jarvis 1982,

1989, 1990, 1992; Jarvis and Cornely 1983). By

1992, the technique involved vertical, large-format color photography of flocked geese from 90

to 130 m above ground, yielding photographs that

permitted subspecies identification for large numbers of geese based on color and size, and enumeration of neck collars by color (Jarvis 1992).

This method was continued through 1997 (fig. 7)

(Jarvis 1993, 1994, 1995, 1997). However, because the method was plagued by aircraft scheduling and weather problems, and because it had

Figure 7—Winter population estimates of dusky Canada geese in Oregon and Washington,

1947-2002, from the three primary methods used to index the population for management

purposes.
38

unknown sampling and statistical properties, the

Pacific Flyway Study Committee discontinued

this method in March 1997 for a more statistically sound estimation technique (Jarvis 1997).

Mark-resight estimates—Beginning in 1990

(fig. 7) (Pacific Flyway Council 1997), markresight methods were investigated as a means of

obtaining indirect estimates of the dusky goose

population on the wintering grounds (Sheaffer

1993). The method employs Chapman’s (1951)

modification to the traditional Petersen estimate

(Le Cren 1965) as described in Seber (1973: 60)

to estimate the total number of marked geese

present. Ratios of duskys marked with colored

neckbands to unmarked duskys are determined

from samples of geese observed during two

resighting periods. A population estimate is developed by expanding the estimated total number

of marked individuals by a factor for the unmarked proportion of the population. Subsequently, a “least-biased” estimator was developed

and applied to the population via observations of

geese marked with uniquely coded neck collars,

and annual population estimates with standard

errors were developed for 1990 through 1993

(Sheaffer and Jarvis 1995). This method was

tested by the USFWS in 1995 for comparison

with results of the traditional midwinter inventory

that used aerial photography method to estimate

subspecies composition (Trost et al. 1995). The

indices were found comparable, and the technique was adopted by the Pacific Flyway Study

Committee as the operational method for annual

post-hunting season estimates in 1997 and thereafter (Drut and Trost 2003, Drut et al. 1997,

Pacific Flyway Council 1997).

Recent discussions on annual indexing methods

have focused on several sources of error apparent

in the mark-resight method. The method assumes

that all marked geese are equally likely to be

observed during resighting survey periods.

Campbell and Becker (1991) reviewed collar

retention rates for dusky geese; collar loss, which

varies among goose poplations, can affect estimates of population size and survival. Results of

recent surveys suggest that the detection rates of

marked geese vary considerably from year to

year. Severe storms in some years have thoroughly mixed duskys to produce exceptionally

effective sampling of all marked geese. Because

the midwinter dusky estimate is derived from a

large geographic area, investigators have concluded that, unless a major weather event occurs,

there are segments of the population that are not

sampled during the resight periods (Drut and

Trost 1999, Drut et al. 1998). Thus, annual population estimates that have fluctuated widely reflect varying degrees of population mixing.

The second issue affecting the indirect winter

indices is the accuracy of the critical marked:

unmarked ratio used to expand the estimates.

From the early 1960s on, it was known from

banding data that, although most birds counted as

duskys were from the CRD, the counts included

similar-looking geese such as Vancouver Canada

geese, and possibly others (Chapman et al. 1969,

Hansen 1962). Recent studies on genetic composition of geese that are classified as duskys for

regulatory purposes (Pearce et al. 1998) support

the presence of “look-alikes” that confound enumeration of unmarked duskys. Over the past 10

years, numbers of urban geese from Anchorage

increased (Crowley 1998), and island geese have

increased (Petrula et al. 2002); both winter sympatrically with CRD duskys (ADFG 1999,

Crowley et al. 1998). Because CRD dusky

numbers declined (Eldridge et al. 1998), the

proportion of non-CRD geese in the midwinter

population estimates of duskys has increased.

Waterfowl managers have not been concerned

about the occurrence of Middleton Island geese

in the dusky winter index because the population

by definition includes island geese. Without good

estimates of the numbers of other geese wintering

sympatrically with and counted as duskys (e.g.,

Vancouvers, large juvenile lessers, stocks of unknown origin), however, it is not feasible to develop an accurate expansion factor to estimate the

number of CRD duskys. Given these problems

with the indirect wintering population estimates,

development of accurate estimates from the

breeding grounds has become increasingly important in monitoring CRD duskys (Drut and Trost

1999, Pacific Flyway Council 1997).
39

Breeding grounds—Similar to the adaptation of

methods on the wintering grounds, estimation of

the population of duskys on the CRD has changed

in response to dramatic succession of habitats and

to demand for more accurate results. Surveys on

the breeding grounds have had to address important biological and environmental factors including (1) variable spring conditions affecting the

phenology of nest initiation and optimal survey

timing, (2) spring weather also affecting residual

snow cover and leaf-out of shrubs that influence

visibility of geese, (3) significant expansion of

shrub communities since the late 1970s compounding visibility problems, (4) variable rates

of nest predation early in the season that affect

the proportion of geese actively nesting and observable as pairs, and (5) variable rates of nest

loss and renesting that complicate attempts to

relate annual estimates of breeding pairs from

aerial surveys to nest densities and production

estimated from ground surveys.

Elkins (1952) provided the first estimate of the

dusky breeding population on the CRD in 1952

at 4,000 nesting geese and 2,000 nonbreeding

geese. Development of a formal breeding ground

aerial survey by the Alaska Department of Fish

and Game began in 1974, when 9.3 percent of the

CRD (788 km2

) was surveyed in mid-May. Geese

were counted in 0.2-km strips on either side of

182 km of linear transects. A population estimate

was derived by expanding strip counts to the area

of the entire study area and by applying a visibility correction factor of 1.25 under the assumption

that 80 percent of geese were visible on transects

(fig. 8) (Timm 1974). Subsequent population

surveys in 1975, 1976, 1978, 1979, and 1980

followed the same procedures but were designed

to also investigate problems of bias associated

with varying densities of geese. Results were

compared among flights with different transect

widths (100 versus 200 m) and ocular versus photographic counts (Timm 1975, 1976, 1978, 1980;

Timm and Sellers 1979).

In 1983, the USFWS assumed responsibility for

the surveys, following the methods of Timm

(1978) but without adjustment for bias in visibility of geese, and covering a smaller study area of

343 km2

 (Conant and Hodges 1986). Both total

geese and breeding pairs were estimated. These

surveys were continued through 1990 (fig. 8)

(Conant and Dau 1989, 1990). Beginning in

1986, the USFWS initiated a second, newly designed survey, using ratio-estimate procedures

and without correction for visibility bias, to provide statistical rigor and comparisons between

counts (Butler 1986) (fig. 8). After 5 years of

overlap with the previous survey method (Butler

1987, 1988, 1989, 1990, 1991), a review was

conducted (Butler and Eldridge 1991) and the

new procedure was adopted as the operational

survey method. This method, including the precise plotting of all goose observations by using

global positioning system locations and a geographic information system, is still in use today

(fig. 8) (Butler 1992,1993,1994; Eldridge and

Dau 2002; Eldridge and Platte 1995, 1996;

Eldridge et al. 1997, 1998; Pacific Flyway

Council 1997).

In 1987-89, in association with the new USFWS

survey, helicopter-based counts were conducted

on a sample of transects in an attempt to develop

a reliable visibility rate correction factor for the

annual fixed-wing aerial surveys (Butler 1987,

1988, 1989). Because of the high costs of helicopter surveys and high variability in the derived

correction factors, the effort to develop a visibility correction factor was terminated (Butler and

Eldridge 1991).

From 1993 through 1995 (Crouse et al. 1997) and

in 1998 (Youkey 1998), the USDA Forest Service

conducted nest censuses of randomly selected

9-ha plots within a 212-km2

 study area. This procedure has become an operational program, to be

conducted once every 3 years (Pacific Flyway

Council 1997). Although confounded by the annually varying extent of renesting, these data,

in concert with renesting studies (Grand and

Anthony 1997, Grand et al. 1998), may at some

point be sufficient to correct and refine aerial

survey indices for duskys (Butler et al. 1995,

Stehn 1999).
40

Population Trend

Midwinter indices from 1947 to the present show

an increasing population until the mid-1970s (fig.

7). Jarvis and Cornely (1988), based on 3-year

moving averages of midwinter counts, concluded

that the dusky population declined 8.3 percent

per year from 1975 through 1984, with most of

that decline occurring since 1979. Based on the

midwinter counts, this decline continued through

1990, with widely fluctuating population estimates since that time (Drut et al. 1998, Pacific

Flyway Council 1997). Some of the variability

in recent years, however, may be attributed to

uneven sampling of marked duskys as discussed

above (Drut and Trost 1999). Estimates from at

least recent years reflect a combination of both

CRD and island geese, obscuring the trend of the

CRD population. These data are consistent with

a rapidly increasing population of island geese

since the late 1980s.

Similar to midwinter indices, breeding ground

surveys (fig. 8) reflected a 50-percent linear decline from 1978 to 1990 on the CRD (Conant and

Dau 1990), with a further decline in 1991 (Butler

1991). In an independent analysis considering

both breeding population estimates and annual

estimates of young produced, Stehn (1992) confirmed an average annual rate of population decrease from 1978 to 1991 of 7 to 8 percent per

year. The population rebounded in 1992, however, to a level similar to that of 1984 (Butler

1992, Conant and Dau 1990). In recent years,

lower indices during 1995 and 1996 were offset

by modestly higher indices during 1997 and 1998

(Eldridge et al. 1998), but both breeding pair and

total goose indices have declined further and

reached all-time lows in 1999 (Eldridge and Dau

2002). Assuming the early breeding ground surveys were equivalent to the current operational

survey, a significant population decline occurred

from 1978 through 1985; since then, however, the

CRD component of the population has fluctuated

substantially after the late 1980s, but has continued a gradually declining trend over the past 10

years (fig. 8). Short-term increases in total geese

during 1992-94 and 2001-02 followed periods

with relatively good production (table 10) but

have not been reflected in subsequent increases in

breeding pairs.

Figure 8—Estimates of total geese and breeding pairs of dusky Canada geese from spring

aerial surveys on the Copper River Delta, Alaska, 1974-2002.
41

Productivity and Recruitment

Productivity of duskys on the CRD has changed

over the nearly three decades of study, with the

major change happening within the period covered by the first method of measurement, so that

the change is unlikely to be an artifact of different

methods. During 1979, low nest success resulted

in low productivity, and although moderate levels

of production occasionally have occurred since

then, consistent high production documented

during the 1970s has not recurred (tables 9 and

10). Over the long term, assuming productivity

estimates did not vary from changes in methods,

production declined from the 1970s ( x = 26.8

percent young, sd = 13.2 percent, n = 9 years) to

the 1980s ( x = 15.4 percent young, sd = 6.7, n =

10), with little or no change during the 1990s ( x

= 14.3 percent young, sd = 7.5, n = 9). Production

in 2000-2002 (x = 26.7 percent young, sd = 3.4,

n = 3) has been the best since the late 1970s, but

the duration of this success and effect on recruitment are yet to be seen. Sheaffer (1993) estimated that production of at least 20 percent

young would be needed to maintain a stable

population. The flyway management plan has

adopted that goal (Pacific Flyway Council 1997).

These levels of production, however, have only

occurred in 8 of the past 20 years (table 10).

In the 1990s, a sustained pattern of low production and population decline raised concerns that

maturing age structure could reduce reproductive

potential. Campbell and Griese (1987) estimated

that over 85 percent of duskys were of breeding

age, with 70 percent in the category of prime

breeders aged 6 to 14 years. Longevity was subsequently noted to be at least 19 years, with evidence of breeding at 17 years (Campbell 1991b).

Chapman et al. (1969) concluded that, to maintain the population when annual mortality averaged 46 percent, at least 50 to 66 percent of

2-year-old duskys must nest annually. Sheaffer

(1993) assumed 80 percent of 2-year-olds nested

with nest success of 30 percent, compared to 40

percent for geese age 3 or older. In recent years,

however, young age cohorts of duskys have been

small, and realized nest success for all ages combined has only reached 30 percent during 1990-

92 (table 9) and perhaps during 2000-2002 (see

table 10).

Survival and Mortality

Hansen (1962) was the first to estimate mortality

rates of duskys. Using the composite dynamic

method, he estimated average annual mortality

rates of 28.9 percent for adults and 56.9 percent

for juveniles during 1952-60. Similarly, Chapman

et al. (1969) analyzed data for 1952-65, yielding

average annual mortality rate estimates of 34.6

percent for adults, 37.7 percent for yearlings, and

57.4 percent for juveniles. In recognition that the

composite dynamic method can yield underestimates of survival rates (Seber 1972), Sheaffer

(1993: 21) reanalyzed and estimated survival

rates for several periods during 1953 through

1990 for normal, leg-banded-only duskys, determining average annual adult survival rates of

65.8 to 77.2 percent and rates of 30.7 to 42.5

percent for immatures (table 12). Both Chapman

et al. (1969) and Sheaffer (1993) noted that adult

survival rates increased over time in tandem with

incremental restrictions in harvest regulations.

Sheaffer (1993) also examined survival estimates

based on resightings of marked birds during

1983-90, and calculated a mean annual adult survival rate of 78.8 percent (se = 6.4 percent, range

= 73 to 85 percent). Survival rates based on

resightings were not significantly different than

rates estimated from leg band recoveries for the

same period.

Following population modeling to simulate what

was known of the dusky population from the

early 1950s through 1989, Chapman et al. (1969)

and Sheaffer (1993) concluded that large harvests

were supportable by the population during the

1960s because the average recruitment rate was

high. Subsequently, as recruitment rates declined

during the 1980s, the population could not continue to increase despite modest increases in adult

survival rates (Sheaffer 1993). Ultimately, low

rates of recruitment accompanied by moderate

adult survival rates resulted in population decline.
42

That is, as recruitment rates declined, population

size became relatively more sensitive to small

changes in adult survival. As severe restrictions

were placed on hunting during the mid to late

1980s, adult survival increased and the population apparently stabilized.

Sheaffer (1993) concluded that the chances for

the population to increase were favorable if recruitment and survival rates remained at or above

levels typical of the late 1980s and early 1990s;

she also noted that the population was likely to

experience greater variation in recruitment rates.

Relative to the previous period of the same duration, production of young seems to have been

more variable and slightly higher during 1990

through 1993 (see table 10), a period characterized by an apparent rebound in the dusky population (figs. 7 and 8).

Limiting Factors

Predators and Depredation

Depredation of geese and eggs—Predators of

geese and goose eggs on the CRD during the reproductive season include brown bears, coyotes,

wolves (Canis lupus), red fox (Vulpes fulva),

river otter (Lutra canadensis), mink (Mustela

vison), bald eagles (Haliaeetus leucocephalus),

northern harriers (Circus cyaneus), short-eared

owls (Asio flammeus), glaucous-winged gulls

(Larus glaucescens), herring gulls (Larus

argentatus), mew gulls (Larus canus), parasitic

jaegers (Stercorarius parasiticus), common

ravens (Corvus corax), northwestern crows (Corvus caurinus), and possibly magpies (Pica pica).

Depredation occurs on nesting adults, eggs, goslings, and molting geese; the known level of intensity, however, varies widely throughout the

season in association with the stages of reproduction and vulnerability of the birds. Further, the

amount of depredation has increased over years.

During initial studies when adult geese and goslings were being banded in the 1950s, several

workers reported the presence of predators. Olson

(1953, 1954a) noted that the potential for nest

depredation was high because bears could literally travel along the slough banks and go from

nest to nest. Despite the ease of access, and the

documented presence of most of the known

predators on the nesting grounds, loss of nests

was minimal (e.g., Elkins 1952). Both Courtright

(in Olson 1954a, 1954b) and Trainer (1959)

found low rates of nest depredation. Hanson

(1962), referring to those studies, noted that there

were so few predators after incubation was completed that juvenile mortality was considered

negligible. Shepherd (1966), however, expected

that depredation, particularly by mammals,

would increase after and because of the 1964

earthquake.

Depredation on adults—Little depredation of

geese is known to occur in early spring. During

arrival on the CRD when geese are concentrated

in the upper delta and on tidal flats in snow-free

areas, flocks of foraging geese are sensitive to

bald eagles that frequently circle overhead flushing geese, indicating at least the possibility of

depredation attempts at that time. As geese disperse, become territorial, begin to lay eggs, and

Table 12—Average annual survival rates of adult and juvenile

dusky Canada geese during selected periods from 1953 to 1990

Adults Immatures

Period Survival rate SEa Survival rate SEa

1953 - 1960 0.658 0.017 0.386 0.029

1965 - 1968 .693 .045 .425 .060

1974 - 1978 .694 .030 .307 .038

1983 - 1990 .772 .044 — —

Source: Sheaffer 1993.

a

 Standard error.
43

become associated with nests, the adults become

more susceptible to depredation. Geese may be

vulnerable to predators while distracted during

territorial disputes, or they may attempt to defend

nests from predators and be killed in the process.

Olson (1954a) found the remains of adult geese at

each of four artificial nesting platforms established the previous year and concluded that

duskys using these sites may have been more

vulnerable to coyotes and bald eagles. Possibly,

for geese nesting in thick cover increasingly typical of the CRD, the birds are unable to efficiently

detect the approach of predators (Bromley 1976).

During intensive nesting studies, early investigators reported no incidents of depredation on nesting adults (Trainer 1959). In five seasons over the

period 1974-79, Bromley (1976, and pers. obs.

1977-79) found one adult male and one adult

female dusky carcass resulting from depredation

by bald eagles and an additional four carcasses

that were probable eagle kills. The annual incidence of adult mortality during nesting increased

in later years (table 13), with responsible predators including bald eagles, coyotes, brown bears

(Campbell 1991c, 1992b; Campbell and Rothe

1986, 1989; Campbell et al. 1987; Crouse 1995;

Crouse et al. 1995; Sellers 1980; Timm 1982),

and occasionally wolves (Stephenson and Van

Ballenberghe 1995). In the latter case, however,

waterfowl were not a major component in the diet

of wolves (Carnes et al. 1996). Based on remains

of adult geese and their nests, bald eagles were

responsible for depredating at least 17 nesting

geese in 1998 (Grand et al. 1998). They concluded that bald eagles are currently a more important predator than was previously thought.

Remains of flightless duskys (based on stage of

wing molt in carcass remains) have been found

occasionally at mink and red fox dens (Bromley

1976). Brown bears have been observed from a

distance engaging in behavior suspected to be

running down and consuming molting geese and

their young (Bromley 1976, Timm in Bromley

1976). Trainer (1959) found fresh remains of an

adult-sized goose in the stomach of an adult coyote taken near Copper (Alaganik) Slough on the

CRD on 28 August. Wolves on the CRD are

known to prey occasionally on molting geese

(Stephenson and Van Ballenberghe 1995).

Depredation on eggs—Eggs were generally not

vulnerable to depredation by gulls and jaegers

Table 13—The number and density of dusky Canada goose carcasses and kill sites determined

during nest searches on the Copper River Delta, Alaska 1980-1995

Number of goose Density

Year carcasses and kill sites (carcasses/km2

) Source

1980 7 1.6 Sellers 1980

1983 3 .7 Campbell 1984

1984 4 .9 Campbell and Rothe 1985

1985 17 3.8 Campbell and Rothe 1986

1986 34 7.9 Campbell et al. 1987

1987 15 3.5 Campbell et al. 1988

1988 26 10.6 Campbell and Rothe 1989

1989 16 6.5 Campbell and Rothe 1990

1990 8 3.2 Campbell 1990a

1991 18 7.3 Campbell 1991c

1992 7 2.9 Campbell et al. 1992

1994 24 3.8 Crouse 1995

1995 11 2.6 Crouse et al. 1995
44

when they were attended by geese (Bromley

1976). During laying and incubation recesses,

however, when geese leave eggs unattended

(though covered with nest material and down) as

they forage away from the nest, eggs are vulnerable to predators. Avian predators such as glaucous-winged gulls are particularly adept at quick

thefts and can carry an egg away from the nest. In

addition, geese may be suddenly disturbed from

their nests by large predators such as bears or

canids, leaving the eggs exposed and vulnerable

to all predators. Although data are few for the

1950s, egg and nest losses to predators were low

during 1954 and 1959, and thought to be almost

exclusively due to gulls and jaegers (Shepherd

1966, Trainer 1959). From the 1964 earthquake

until about 1978, however, the rate of egg loss to

both mammalian and avian predators progressively increased from less than 10 percent to

greater than 50 percent (table 9).

During most dusky goose nest studies over the

years, investigators routinely have covered nests

with nest material and down as soon as nests

were found, which apparently compensated for

disturbance that might otherwise have resulted

in higher nest loss. Bromley (1976: 37) tested

for human effects by using two methods and

found no difference between control and experimental nests. Similarly, from 1983 through 1989,

Campbell et al. (1987, 1988) and Campbell and

Rothe (1989, 1990) annually compared the fate

of nests checked repeatedly to those located only

after nesting was completed; no visitation effect

was evident.

Although the rate of egg loss was rising after the

1964 earthquake, beginning in 1979, the annual

rate of egg depredation rose dramatically (table 9)

as illustrated by losses noted by Courtright (in

Olson 1954a), Shepherd (1966), and Bromley

(1976) compared to data in Bromley (1979) and

Campbell (1990a). Beginning in 1982 (Campbell

1990a), nest depredation was classified as avian,

unknown mammal, canid, or bear based on evidence as defined in Darrow (1938), Sooter

(1946), and Rearden (1951). From 1982 through

1987, over half of nest losses were caused by

bears (Campbell 1991c). Additional loss was

caused by canids, primarily coyotes (about 20

percent of annual losses), and by avian predators

that on average accounted for 16 percent of

losses, although proportions of losses attributed

to specific predators differed greatly between

years (Campbell 1990a). The accelerated rate

of nest loss from mammalian predators coincided

with a substantial increase in the number of adult

goose carcasses found at nest sites during the

mid-1980s (table 13).

Bears observed on the nesting grounds (presumably the individuals responsible for the nest loss)

were predominantly immature animals and sows

with cubs (Bromley 1976, Campbell 1991c,

Mickelson et al. 1980). Bears moved onto the

outer delta (primary nesting area) to graze on

emerging grasses and sedges when geese were

initiating nests; Campbell (1991c) suggested

this was coincident with early spring phenology.

Although he concluded that bears substantially

influenced annual production of goslings, an experimental removal of 40 to 60 percent of brown

bears on the west CRD during nesting in 1987

did not result in increased nest success of geese

(Campbell et al. 1988). Rather, other forms of

nest loss increased, most notably a doubling of

avian depredation on goose nests.

From 1987 to 1998, nest losses to predators remained high (Campbell and Rothe 1989, 1990;

Campbell et al. 1992; Crouse et al. 1997; Grand

et al. 1998; Youkey 1998) and have included occasional depredation by wolves (Stephenson and

Van Ballenberghe 1995). Loss to mammalian

predators, however, has declined since 1990,

perhaps partially in response to widely flooded

areas and wetter habitat caused by beaver activity

(Campbell 1992b).

As loss of nests to mammalian predators has declined, loss to avian predators has increased, and

new evidence is emerging that bald eagles are

currently a significant predator on eggs and

geese. In 1997 and 1998, Grand and Anthony

(1997) and Grand et al. (1998) used remote video

cameras at goose nests to document predators at

four destroyed nests each year. In all cases, bald

eagles were the predators caught on camera destroying eggs. Of 193 depredated dusky nests in
45

1997 screened through evidentiary filters following Sargeant et al. (1998), Grand and Anthony

(1997) attributed 88 (46 percent) exclusively to

eagles, none exclusively to other avian predators,

2 to bears, 1 to mink, and 4 to canids; 98 (51 percent) could not be assigned to any one predator.

Data were similar for 311 nests lost in 1998:

Grand et al. (1998) attributed 165 (53 percent)

exclusively to eagles, none to other avian predators, 1 to mink, and 1 to bears; 146 (47 percent)

were not classified. These studies are continuing.

Bernatowicz et al. (in press) found that 97 percent of relocations of radio-marked territorial

eagles were within 2 km of their nest sites, indicating that these birds likely conducted most of

their foraging close to their nests. As noted

above, ongoing plant succession on the CRD is

causing an increase in the availability of eagle

nest sites on the nesting area of geese.

The temporal pattern of nest depredation within

a season also has significance to the productivity

of dusky geese. Most nest losses to predators

occur early in the nesting season—during egg

laying and early incubation. Thus, although relatively low in absolute numbers, renests and lateinitiated nests have higher daily survival rates

than early nests (Grand et al. 1998). There is an

obvious increase in predator numbers and activities associated with the start of the eulachon

(Thaleichthys pacificus) run on the CRD, and

some observers have suggested that the availability of eulachon, as alternative prey, causes a decline in depredation of nests and adult geese

midnesting (Babler 1999, Grand 1999). The relation of the timing of the eulachon run, which

differs annually, to the timing of goose nesting

(also differs annually) may determine when the

usually high rate of early nest depredation subsides. For example, if nest initiation is late and

the eulachon run is early, the most intensive period of nest loss would end quite soon and result

in greater nest success than if nesting began early

and the eulachon run was late.

Depredation on goslings—There is evidence

that goslings are killed by glaucous-winged gulls

(Bromley 1976), bald eagles (Bromley 1976,

Grand and Anthony 1997, Mickelson et al. 1980),

mink (Bromley 1976, Grand and Anthony 1997),

red fox (Bromley 1976), coyotes (Olson 1954a),

wolves (Grand and Anthony 1997, Stephenson

and Van Ballenberghe 1995), and brown bears

(Bromley 1976, Timm in Bromley 1976, Trainer

1959). Grand et al. (1998) studied the causes of

dusky Canada goose gosling mortality in 1997

and 1998 (table 14); small carnivorous mammals

and eagles each accounted for about one-quarter

of the observed mortalities. In an examination of

the stomach contents of 38 glaucous-winged

gulls collected in July and August, Olson (1954b)

found only 1 that contained the remains of waterfowl.

Predator numbers and trends—

Brown bear—Since the 1800s, brown bears have

probably increased in the region of the CRD

(Morgan 1989). Although bears had no effect on

rates of nest loss during the two seasons of study

before 1964, all biologists working on the CRD

during the 1950s mentioned the presence of

brown bears. Brown bear tracks were common on

the delta in 1953 (Olson 1953), and bears were

not uncommon in 1954 (Olson 1954a). Klein

(1955) noted that bears were commonly seen on

the flats during his work 13-31 July 1955. In

1959, brown bears were common to the wooded

upland area of the delta, but were observed only

occasionally beyond the limits of the shrubs and

trees; nevertheless, a subadult brown bear was

collected on the nesting area of the outer delta on

23 June (Trainer 1959). Shepherd (1966) reported

his impression that bears had increased in abundance since before the earthquake, noting the

high population of microtine rodents (e.g., voles:

Microtus spp. and Clethrionomys spp.) in 1965 as

a possible attraction, and he speculated that bears

might continue to increase.

Campbell (1984) conducted an intensive study

of brown bears on the CRD, and estimated that

a minimum of 22 to 27 bears used the outer delta

during May and June that year. Similarly,

Mickelson (1984) interviewed local residents

and, after adding his personal experience, speculated that 20 to 30 brown bears were annually

present on the nesting grounds of the western

CRD. Studies by Campbell (Campbell and Rothe
46

1986, Campbell et al. 1987) yielded estimates of

at least 33 bears in 1985 and 35 to 48 in 1986.

Bear numbers in Alaska Game Management Unit

6C (western CRD) were estimated at 60 to 85 in

the mid-1980s (Campbell and Griese 1987), and

100 to 106 during 1989 to 1992 (Nowlin 1995),

illustrating an increase over a period of dramatic

successional changes in habitats on the nesting

area. During 1993 to 1997, estimates of the bear

population increased each year to 120 bears in

1997 (Crowley 1999b). In his telemetry study on

the CRD, Campbell (1991a) demonstrated great

mobility among bears and recorded some aspects

of goose nest predation by sex and age class of

bears and other factors affecting the impact of

bears on breeding dusky geese.

Canids—Although the red fox was considered

abundant in the 1950s with about 50 to 60

trapped on the delta annually (Mickelson 1984),

there were so few in the 1980s that Campbell and

Griese (1987) did not consider them in a review

of predators of geese. In contrast, coyotes were

considered a common and important predator

(Campbell 1990b, Campbell and Griese 1987).

Indeed, more numerous coyotes may play

a role in discouraging red foxes from the CRD

(Sargeant et al. 1984, Voight and Earle 1983).

During the 1950s and 1960s, aerial gunners and

trappers took 30 to 40 coyotes per year from the

CRD (Campbell and Griese 1987, Mickelson

1984); however, harvest declined thereafter because of low fur prices. Coyote populations seem

closely associated with microtine rodent numbers, likely increasing substantially when vole

(Microtus oeconomus) numbers irrupt on the

CRD (Campbell 1991c). Based on frequent but

incidental observations during intensive study

of wolves on the CRD, Carnes et al. (1996) concluded that coyotes were abundant during the

1990s. Because of high interest in harvest of

wolves on the western CRD (see below), humans may have enhanced the success of coyotes

(Carnes et al. 1996), a more active and common

goose predator. Where both species occur, wolves

tend to displace coyotes and there is typically an

inverse relation between their densities (e.g.,

Mech 1970). Reduction of wolves on the CRD

may have promoted expansion of coyotes. There

likely has been an overall increase in coyotes on

the western CRD since the 1950s, partly in response to reduced harvest by humans, and possibly in response to the successional increase of

brushy habitats in goose nesting areas.

Wolves became established in the 1980s on the

western CRD (Stephenson et al. 1993), in association with the successful introduction of moose

(Alces alces) during 1949-58 (MacCracken

1992), and with the termination of predator control programs (Crowley 1999a). Although wolf

numbers initially increased to two packs totaling

7 to 20 animals in the 1980s, subsequent harvest

and illegal take have reduced them to low density

(Carnes et al. 1996). Although few in number,

Table 14—Dusky Canada goose gosling mortalities attributed to types of predators on the

Copper River Delta, Alaska, 1997 and 1998

1997 1998 Total

Cause of mortality Number Percent Number Percent Number Percent

Unknown 9 26 11 34 20 30

Small mammals 8 24 10 31 18 27

Eagle 9 26 8 25 17 26

Avian 5 15 2 6 7 11

Wolf 3 9 1 3 4 6

Subtotal 34 32 66

Missing 7 9 16

Total 41 41 82

Source: Grand et al. 1998.
47

wolves have had a regular presence on the western CRD during the past 20 years. Thus, because

there were no wolves present earlier, the goose

nesting area has experienced, in effect, an increase in wolves.

Avian predators—Glaucous-winged gulls and

parasitic jaegers were common on the western

CRD in 1954 (Olson 1954a), and Klein (1955)

found gulls and jaegers abundant the following

year. Trainer (1959) considered the glaucouswinged gull to be common, and the mew gull to

be abundant; parasitic jaegers were present but

not considered an important predator. About 250

jaegers were estimated to be on the entire CRD

in May and June 1963 (Isleib and Kessel 1973).

Mickelson et al. (1980) estimated 12 to 13 pairs

on the eastern CRD, and Mickelson (1984)

speculated there could be 10 to 25 pairs annually

on the western CRD. There are no current estimates of numbers or trends for mew gulls and

parasitic jaegers on the CRD. Glaucous-winged

gulls increased in the region during the 1970s.

Mickelson (1984) estimated 5,600 pairs on Egg

Island, just offshore of the western CRD, in 1975.

In 1979, Patten (1980) recorded 10,000 pairs on

the island, making it the largest glaucous-winged

gull colony in the world. Patten and Patten (1979)

estimated that these gulls were increasing at the

rate of 4 percent per year in the 1970s.

Common ravens occur on the nesting grounds but

are not numerous. Trainer (1959) reported that

they moved out onto the delta after the goose

nesting season; however, Bromley (1976) and

Youkey (1995) reported them as occasional egg

predators during the nesting season. If ravens are

more closely associated with the wooded areas

than the nonforested parts of the delta, they likely

have increased on the nesting grounds over the

past 20 years as the amount of forested, closed

habitat has increased on the outer delta.

Bald eagles commonly nested on the inland portion of the western CRD during the 1950s but

usually were seen only passing overhead on the

outer delta (Trainer 1959). In late May or early

June, however, an annual spring run of eulachon,

a candlefish, attracts large numbers of gulls and

eagles to the primary nesting grounds of the geese

(Bromley 1976, Grand and Anthony 1997,

Trainer 1959).

In response to bounties offered on eagles to protect fisheries, about 100,000 eagles were killed

in southeast Alaska from 1917 to 1953; many

of these likely were taken in the PWS region because high eagle numbers overlapped with human

activity there (Schempf 1999). Before the Exxon

Valdez oil spill in PWS in March 1989, there

were no population data for bald eagles in the

region. Since the spill, population estimates and

trends have been measured for several years to

assess the effects of the spill. After an initial decline in productivity in western PWS during the

1989 reproductive season (Bernatowicz et al.

1996), eagle production recovered, and the PWS

population has since increased at an average rate

of 2.0 to 3.7 percent per year (Bowman et al.

1995, 1997).

An eagle survey of the western CRD in 1990,

uncorrected for detection rates, yielded documentation of 112 bald eagle nests, 64 of them occupied, and several of them in atypically small,

young Sitka spruce (Picea sitchensis (Bong.)

Carr.) (Bowman 1999). Because of rapid plant

succession during the 1990s, new nest sites are

becoming available every year as trees appropriate in stature for nesting eagles mature on the

outer delta. Because nest sites appear limiting

for eagles on the delta (Bowman 1999), it is

likely that the nesting population on the western

CRD will continue to expand. As an example,

where there were no trees on a high-density goose

nesting study area of a few km2

 during 1976

(Bromley 1976), trees of sufficient stature hosted

at least three recently established bald eagle nests

in 1998 (Grand 1999).

In summary, bald eagles probably have increased

steadily since the end of the eagle control program in 1953. The PWS population increased at

a rate of 2.0 to 3.7 percent per year from 1989

through 1995 (Bowman et al. 1997). More specifically, as new nesting habitat has developed

on the CRD after the 1964 earthquake, the eagle

population is expanding on the goose nesting

area.
48

Other predators—There has been no documentation of numbers or population trends of other

predators on the western CRD.

Predator management—Predator management

is expensive and controversial, yet some managers have suggested it is the most obvious and

feasible solution to severe depredation of dusky

goose nests on the CRD (Campbell 1990a). The

discussion above indicates that the array of predatory agents on the delta has changed and likely

will change further over time, as rapid and substantial succession in an already dynamic system

causes predatory species and their primary and

alternate prey to fluctuate in numbers and availability. Further, there may be changes in relative

vulnerability of dusky geese to specific predators

among life history stages—which agents prey on

adult geese, eggs, and young. The suitability of

predator management as a means to sustain and

enhance the dusky goose population requires an

understanding of the status and direction of ecological factors, and consideration of both public

resource objectives and social concerns

(Campbell and Griese 1987, Pacific Flyway

Council 1997).

Based on a review of predator management

options for the CRD and the public involvement

process (Campbell and Griese 1987), the Alaska

Department of Fish and Game rejected control

of brown bears, by increased public hunting or

control by state personnel, as a reasonable management alternative. Public opposition to bear

control and to reduction of public use and enjoyment of bears were factors, but also, because of

their life history characteristics, brown bear

populations are difficult to manage precisely

(Miller 1990, 1997). Removal or protection of

only a few females can mean the difference between an increasing bear population or a decline

with the possibility of consequential and undesirable changes in population structure that may

require decades of intensive management to correct (Miller 1990, Taylor et al. 1987).

Based on high rates of nest depredation by bears

in the 1980s, Campbell and Griese (1987) suggested that control of bear numbers would result

in increased nesting success of geese. In a test of

this hypothesis, 16 bears were translocated from

the delta 150 km east to Cape Yakataga in spring

1987 before the peak of nest initiation. At least

six of these bears eventually returned to their

original home ranges on the CRD, including four

that returned before the peak of hatch was over

(Campbell 1999, Campbell et al. 1988). Nest

success did not increase, but unusual circumstances confounded interpretation of experimental results. Rainfall was exceptionally high during

the nesting season, and the level of nest flooding

and abandonment was higher than normal (table

9). In addition, the potential reduction in nest

losses from bears was offset by avian predation

that reached an unprecedented level. Thus, investigators concluded that to be consistently effective, predator control would need to encompass

bears, avian predators, and possibly coyotes

(Campbell et al. 1988).

Hunting is an effective means of managing brown

bears on the CRD, but requires careful administration (Campbell and Griese 1987). Regulations

for brown bears were restricted in 1968, yielding

a lower harvest of bears in the region (table 15).

Hunters were allowed to take only one bear every

4 years, rather than one per year. Whereas an

average of four bears were harvested annually on

the western CRD in the 1960s, the average harvest declined to 3.1 per year during the 1970s

(table 15). The harvest rate began to increase,

however, during the 1980s and, by the 1990s,

reached the level of the 1960s (table 15). In 1997,

regulations were liberalized to reduce predation

on moose calves on the eastern CRD; hunters

again were allowed one bear every year, rather

than every 4 years. The current conservative strategy for brown bear harvest on the CRD has

guidelines that constrain annual harvests to < 5

percent of the population, composed of no more

than 40 percent females. The strategy supports a

management objective of maintaining about 100

brown bears on the CRD. The current brown bear

population in Unit 6C (western CRD) provides

for a maximum annual harvest of six bears

(Crowley 1999b).

Testing the effectiveness of taste aversion conditioning as an attempt to dissuade nest predators,

particularly bears and coyotes, from taking goose
49

Table 15—Harvest of brown bears on Alaska Game Management Unit 6C, the

western Copper River Delta, 1961-2000

Number of bears harvested

Year Females Males Unknown Total

1961 1 0 0 1

1962 0 1 0 1

1963 1 1 0 2

1964 0 3 0 3

1965 3 6 0 9

1966 2 3 0 5

1967 1 6 2 9

1968 2 7 1 10

1969 0 2 0 2

1970 2 0 0 2

1960s mean: 1.2 2.9 0.3 4.4

1971 1 3 0 4

1972 0 1 0 1

1973 1 3 0 4

1974 1 0 0 1

1975 3 4 0 7

1976 0 1 0 1

1977 0 3 0 3

1978 1 3 0 4

1979 2 2 0 4

1980 2 2

1970s mean: 1.0 2.2 0 3.1

1981 1 2 0 3

1982 2 2 0 4

1983 2 5 0 7

1984 1 3 0 4

1985 3 0 0 3

1986 1 3 0 4

1987 2 4 0 6

1988 3 2 0 5

1989 1 4 0 5

1990 0 2 0 2

1980s mean: 1.6 2.7 0.0 4.3

1991 3 5 0 8

1992 1 1 0 2

1993 0 0 0 0

1994 3 3 0 6

1995 3 2 0 5

1996 1 4 0 5

1997 2 4 0 6

1998 1 2 0 3

1999 1 5 0 6

2000 2 2 0 4

1990s mean: 1.7 2.8 0.0 4.5

Note: Annual harvest for the regulatory year includes hunts in fall and following spring.

Source: Alaska Department of Fish and Game 2000, Nowlin 1995, Crowley 1999b.
50

eggs also has been suggested (Campbell and

Griese 1987). Because this type of research

would be expensive with uncertain benefits to

the dusky goose population, trials have not been

conducted but may be warranted in the future

(Pacific Flyway Council 1997).

Campbell and Griese (1987) also recommended

liberalization of hunting and trapping regulations

for coyotes in Game Management Units 6C and

6B on a trial basis, with monitoring of coyote

harvests and coyote population trends. If the

coyote population failed to respond, they recommended removal of coyotes by trappers sponsored by Alaska Department of Fish and Game.

In 1987, the Alaska Board of Game encouraged

increased harvests of coyotes on the CRD by

liberalizing seasons and bag limits for hunting

and trapping and permitting night lighting as a

legal method of take in Unit 6. Because of the

low value and poor quality of coyote fur from the

CRD, there was little interest by hunters and trappers in pursuing this opportunity. In 1993, these

regulations were retracted, and the harvest remains low at about 20 per year (Crowley 1999a).

The suspected relation of early nest success to

the timing of the eulachon run remains undocumented. If it proves accurate, one important implication might be that predator management

efforts could effectively be focused during an

annually variable but relatively brief period from

initiation of nesting to the beginning of the eulachon run. In a best-case scenario, simply providing food to nesting eagles on high-density goose

nesting areas until the eulachon run begins may

significantly increase nest success of geese.

Considerable thought has been given to predator

management on the breeding grounds, and the

current view of managers is that, although direct

predator control is not warranted now, experimental and operational controls are deemed necessary if the dusky population declines rapidly

from the present level. The increasingly intensive

management options planned in the event of significant population declines, as presented in the

flyway management plan (Pacific Flyway Council 1997), are designed to incorporate the results

of depredation studies presently underway.

Hunting Mortality

There is good evidence that hunting mortality

can be a limiting factor for the dusky population.

Duskys are known to be vulnerable to hunting

and may be heavily harvested (Chapman et al.

1969, Hansen 1962, Jarvis and Cornely 1988).

They frequent small fields, which provides better

access to the birds by hunters, they approach

fields at lower altitudes with less circling before

landing, and they feed with smaller numbers of

other geese than do other races of Canada geese

(Havel and Jarvis 1988); they are known to be 2.7

to 3.0 times more vulnerable to hunting than are

Taverner’s Canada geese (Jarvis and Cornely

1988, Simpson and Jarvis 1979). Kebbe (1958)

noted that the dusky population wintering in

western Oregon ranged from 3,800 to 7,500 during 1947-55, but that with reductions in bag limits and season length during the subsequent 3

years, duskys progressively increased from 8,400

the first year to 14,500 the third year. About twothirds of the annual harvest of duskys occurred in

Oregon through the mid-1980s (Chapman et al.

1969, Hansen 1962, Timm et al. 1979). After

regulations were restricted in 1985, however, the

Oregon proportion of the dusky harvest declined

to less than 40 percent (see table 7), illustrating

that a large degree of harvest control can be

achieved within one jurisdiction.

Based on 1,129 leg band recoveries from 3,943

duskys banded during 1951-60, Hansen (1962)

estimated mortality rates of 57 percent for juveniles and 29 percent for adults. Through examination of Oregon’s hunting season length, bag

limits, and midwinter population estimates during

this same period, he concluded that hunting restrictions during the mid-1950s yielded reduced

direct band recovery rates and a subsequent increase in the winter inventory. Through an analysis of age ratios in the weekly harvest, Hansen

(1962) observed that the kill of adults increased

sharply after 26 December. He suggested that by

curtailing the harvest after this date the population could be increased, providing for a larger

harvestable surplus within a few years, particularly if some winter refuge were provided.
51

Before the establishment of new federal wildlife

refuges, hunt clubs strongly influenced the distribution and harvest of wintering duskys in Oregon

(Chapman et al. 1969, Hansen 1962). Chapman

et al. (1969) report that, in the absence of a public

refuge program, the harvest could have been

much greater had the hunt clubs not provided

refuge and regulation of the take. By the late

1960s, however, refuges had assumed this role

(Chapman et al. 1969, Hansen 1968).

Chapman et al. (1969) updated and extended

Hansen’s (1962) work for 1952-66, for which

they estimated a mean annual population mortality of 45.6 percent, a rate that requires maximum

productivity to be sustainable. Chapman et al.

(1969) also concluded that neither the capacity

of the nesting grounds nor the wintering grounds

were limiting at that time. During this time,

Henny (1967) estimated that natural mortality

accounted for only 5.6 percent of annual mortality, with the remainder attributable to hunting.

Winter refuge was provided in the mid-1960s

(Chapman et al. 1969), the bag limit in Oregon

was reduced to two by 1971, and season length

was varied according to the size of the fall flight

estimate (Pacific Flyway Council 1997). The

postseason population increased from 10,000 to

17,795 during 1952-65 and to 22,000 to 25,500

during 1976-80.

Cornely et al. (1985) estimated that the adult

component of the annual harvest averaged 55.8

percent (range: 46.7 to 64.1 percent) during 1975-

84, compared to 32 percent (range: 22.3 to 38.5

percent) during 1964-66 (Chapman et al. 1969).

Simpson and Jarvis (1979) estimated a population kill rate (retrieved harvest + wounding loss)

of 38 percent in the 1977-78 season. From 1971

to 1983, winter population mortality rates were

highly variable, from 16.9 to 47.7 percent ( x =

26.1 percent) over the 13 years (Jarvis and

Cornely 1988). On examining results in detail,

these authors noted that average winter population mortality of 24 percent from 1971 to 1978

was close to average annual recruitment of 28

percent (range: 10 to 50 percent), whereas from

1979 to 1984, average winter mortality of 30 percent greatly exceeded average recruitment of 19

percent (range: 15 to 24 percent). Thus, low recruitment from 1979 through 1984, in concert

with high rates of mortality (largely from hunting), resulted in declining numbers of duskys

(Jarvis and Cornely 1988).

Beginning in 1984, hunting restrictions were applied to give extra protection to duskys in order to

arrest their decline. Seasons were delayed in

Alaska to allow the departure of duskys from the

state before the hunting season, and bag limits

and seasons were reduced in both Washington

and Oregon (Pacific Flyway Council 1997). In

1985, hunting was limited to a quota of 300

duskys, reduced to 200 in 1995, with the Canada

goose season to be closed in western Oregon and

southwestern Washington when the quota was

reached. This approach was successful, yielding

annual harvests of only 130 to 278 duskys since

1985. A quota of 250 is in effect today. Campbell

and Griese (1987) estimated annual hunting mortality of about 3.5 percent, and Sheaffer (1993)

found no difference in monthly or period survival

rates of duskys between harvest and nonharvest

periods. In conclusion, hunting can and has limited the dusky Canada goose population, but,

through the successful implementation of effective hunting regulations, it is unlikely that it is

currently limiting the population.

Breeding Habitat and Recruitment

Habitat changes on the CRD accelerated by the

uplift in 1964 have led to an increasing diversity

of predators with greater predatory effectiveness,

leading to lower nest success of geese. As reviewed earlier, studies of nest success have indicated that rates of depredation are similar in the

various types of habitat used by nesting geese;

that is, nests in each habitat type are preyed upon

in proportion to the number of nests located there

(Campbell 1990b, Crouse et al. 1997). Thus, although the predatory agents largely responsible

for nest loss have changed over time, nests seem

to be similarly susceptible to destruction regardless of the habitat type in which they are found.

In a major effort to explore the possibility of decreasing nest depredation on duskys, personnel

of the Chugach National Forest, USDA Forest

Service, experimented with different types and
52

locations of artificial nesting islands (ANI) on the

western CRD from 1983 to 1994 (Babler et al.

1998). Based on monitoring of 861 ANI, they

were able to determine the preferences of geese

in terms of size of the ANI, height above water,

aerial cover (shrubs), and distance from shore.

Further, they recommended the two best types of

ANI, considering use by geese and cost of construction and maintenance. Geese preferred ANI

that were 2 to 2.5 m2

 in diameter, with freeboard

of >15 to 20 cm, aerial shrub cover of 50 to 60

percent, and located 20 to 40 m from shore. The

two types of ANI recommended were fiberglass

floaters and sandbag islands (Babler et al. 1998).

These investigators recommended continuation

of the ANI program, with specific suggestions for

improving efficiency in the program, and they

listed appropriate actions to be taken should the

population decline below 8,000 geese.

Over the history of the ANI program from 1984

to 2000, use of ANI by nesting geese ranged from

9 to 32 percent; however, 28 percent of fiberglass

floater islands were used (Meyers et al. 2000).

These rates are much lower than rates measured

in other areas to the south (Babler et al. 1998)

and may reflect a low preference for islands by

duskys, or low survival of platform-born young

that would be predisposed to nest at these sites.

From 1984 to 2000, annual nest success of ANI

nests with known fates averaged 64 percent and

depredation averaged 27 percent, whereas nest

success averaged 29 percent and depredation 57

percent at natural sites, demonstrating that ANI

were effective at achieving reduced rates of nest

loss for geese (Meyers et al. 2000).

A current trend of particular interest is the tendency for eagles to establish new nest sites in

maturing cottonwood (Populus balsamifera L.)

and spruce trees on the nesting grounds of the

outer delta (Grand 1999). Most of the 112 nests

found during the 1990 survey were located on the

upper delta. Assuming that the cottonwoods and

spruce required for nesting habitat of eagles develop on the outer delta (MacCracken 1992,

Thilenius 1990b, Witten 1995), many more nest

sites may become available on the nesting

grounds. Given the tendency of adult eagles to

remain within 2 km of their nest sites during nesting, and a nesting chronology with egg laying in

mid to late April through early May (Bowman

1999), overlapping with duskys, these efficient

predators will become increasingly active on the

high-density nesting areas of the geese. Their

depredation on nesting female geese as well as

on goose eggs has the potential to greatly increase their effect on the dusky goose population.

Natural changes continuing on the CRD will

lead to changes in habitat that will affect the

types of depredation on nesting geese and their

eggs. Colonization of the area by beaver in the

mid-1980s caused the creation of many ponds

and extensive areas of wet habitat, perhaps deflecting mammalian predators from many dusky

nest sites (Campbell and Rothe 1989, Campbell

et al. 1988). Nevertheless, avian depredation increased concurrently with decreasing depredation

from mammals (Campbell et al. 1988), leading to

little change in the net rate of nest loss. Undoubtedly some habitat changes will occur on the CRD

that are unpredictable and will cause similarly

unpredictable chains of events to occur that may

be beneficial or detrimental to goose productivity.

Ongoing studies and monitoring activities will

help provide for early detection and adaptive

management actions to take advantage of opportunities or attempt to mitigate detrimental habitat

changes as they occur.

Summary of Ecology and Ecosystem Dynamics With Regard

to Foreseeable Environmental

Conditions

Ecology and Ecosystem Dynamics

The dusky Canada goose is an evolutionarily

young race of Pacific Flyway goose, adapted to

nest in coastal Alaska and to winter in the mild,

wet climate of the Pacific Northwest. On wintering grounds during late winter and early spring,

mature individuals feed in rich agricultural croplands to gather peak lipid reserves that subsequently play an important role in meeting energy

requirements of geese through migration, prenesting, egg laying, and incubation. Beginning in

early to mid April, they migrate about 2,600 km
53

along a route largely characterized by rugged

fjords with occasional small river deltas and

arrive in mid to late April to nest on the CRD in

south-central Alaska. The prelaying period on the

nesting grounds is at least 13 days, allowing birds

to uniquely time egg formation according to annual spring phenology. Geese time their nesting

to coincide with snowmelt and early availability

of new-growth vegetation, typically early to mid

May, although the range of nest initiation dates

has ranged from late April to early June. Annual

nest success is highly variable, affected primarily

by spring weather conditions and nest depredation. Within the nesting season, the rate of nest

loss to predators is high during laying and early

incubation, but relatively low during the late nesting period. Duskys lay a clutch of about five

eggs, incubate them 27 days, and typically fledge

young early to mid August. Adult geese begin

molt as early as the first week in July, with

most regaining flight by early to mid August. A

postmolt dispersal results in a shift in distribution

to new feeding areas on the CRD, often from the

western CRD to the eastern CRD. Fall departure

begins in early September and peaks in early

October, generally after a staging period near the

nesting grounds during September. Geese begin

arriving on wintering grounds in southwestern

Washington and western Oregon in late September, with peak arrival at the southern terminus in

the southern Willamette Valley in early to mid

November.

The summer habitat of the geese is located in a

highly dynamic region, influenced by tectonic,

glacial, riverine, and tidal forces. Before 1964,

the nesting grounds of the geese were characterized by extensive areas of salt marsh on the outer

CRD, maintained by regular tide cycles and by

storm tide surges. Although the population of

geese was fairly low before the 1964 earthquake,

perhaps 7,000 to 10,000 on average, the birds

were highly productive, with only a small percentage of eggs lost to tidal flooding and even

fewer to predators. During the 1950s and 1960s,

the population supported a large annual harvest,

mainly on their wintering grounds. Hunting mortality was the primary factor limiting the population of duskys at that time. The severe earthquake

of 1964 uplifted the CRD 1.8 to 3.4 m in an apparently long-lasting cycle of uplift and subsidence. Postquake studies have revealed that the

delta had been similarly uplifted at least four

times previously, with a frequency interval of 600

to 900 years. Buried forest horizons from dry

periods provide an indication of what can be expected on the nesting grounds, (i.e., accelerated

succession from open, graminoid marsh habitat

toward extensive shrub and closed spruce-cottonwood forest habitat). In fact, much of the succession has already transpired and is quite obviously

ongoing. There are now trees large enough to

support bald eagle nests in the midst of the nesting grounds of geese.

Associated with habitat changes, predator numbers and diversity have increased on the nesting

grounds, leading to increased rates of eggs and

nesting adults lost to predators, and thus to declining productivity. Brown bears, coyotes, and

bald eagles were present before the earthquake,

but their activity was apparently deterred by wet

(and possibly salty) habitat and extensive inundation of the nesting grounds by high spring tides.

In the absence of tidal inundation, however, and

given increasing shrub and forest habitat, these

species are currently considered effective predators on the geese and their eggs. The lowered

recruitment rate of duskys combined with a high

mortality rate of both adults and young caused

the population to decline. The population recently

may have become stabilized because of a near

cessation of harvest and a high rate of survival of

adults.

During the past 25 years, large numbers of several other races of Canada geese and increasing

numbers of island geese have begun to winter

sympatrically with duskys. Because some of

these races are similar-looking birds, it is not

feasible to specifically estimate the population

size and harvest of the CRD subpopulation of

duskys. Protection of duskys in the face of burgeoning numbers of other geese and an associated

leap in complaints of agricultural depredation has

become increasingly complex. Ongoing innovative and effective management measures are being developed to minimize the harvest of duskys

and to increase the reliability of inventories in the
54

overwhelming presence of other Canada geese.

Thus, establishment of refuges and intensive

management efforts on the wintering grounds

assure the security of duskys at that stage of their

life history.

Short-Term Outlook

The accelerated rate of succession on the outer

CRD almost certainly will continue for some

time (Boggs 2000, Thilenius 1995, Witten 1995),

increasing the extent of closed habitats that were

atypical on preearthquake nesting areas. The productivity of geese likely will remain low, although the predators responsible for nest destruction may change over time according to the

changing suitability of successional habitats for

predator species. For example, numbers of nesting bald eagles will continue to increase on the

nesting grounds of the geese as spruce and cottonwood trees mature to sizes that can support

bald eagle nests. Nesting geese and their eggs

likely will be vulnerable and potentially suffer

increasing rates of loss to eagles. Perhaps at some

point, increasing vegetative cover will begin to

protect geese from eagle depredation. The pattern

observed to date, however, is that there always

will be the possibility of another predator species

emerging as the most effective agent for that

stage of succession.

Although new habitat similar to preearthquake

conditions is developing on the outer marsh in

the previously subtidal zone, rate of development is so slow that extensive, high-quality new

nesting habitat is not expected in the short term.

Geese likely will use new habitat as it develops.

Until it is sufficiently extensive to support a dispersed nesting population, however, rates of nest

loss in new marsh likely will be similar to that of

the old marsh.

The ANI program of the USDA Forest Service

is expected to continue and may help to boost

production of geese to a small but possibly significant degree. With 17 years of experience researching and testing the preferences and

requirements of nesting geese and maintenance

requirements of different designs of ANI, the

Forest Service is in an excellent position to carry

on an effective and efficient program to enhance

nest success and production. Given the dynamic

nature of the system, an ongoing monitoring and

evaluation program will be a necessary part of

this management effort.

Given that geese will be facing the consequences

of low annual productivity from high rates of

depredation on eggs, young, and possibly nesting

adults, harvest rates will have to be maintained at

low levels. Currently low and minimal rates of

harvest are essential and must be viewed as an

ongoing management requirement into the foreseeable short-term future.

Medium-Term Outlook—

Implications of Source-Sink

Metapopulation Dynamics

The concept of metapopulations can be useful in

wildlife conservation (McCullough 1996), although it may be rare that conditions defining

them are met in the real world. Metapopulations

are systems of local populations connected actually or potentially by dispersing individuals

(Eriksson 1996, Levins 1968). More rigorously

defined, a metapopulation is spatially structured,

with small subpopulations relative to others, subpopulation dynamics are asynchronous, and dispersal is sufficient to ensure recolonization, but

not so great as to erode local asynchrony (reviewed in Wiens 1996). Although dispersal between subpopulations of duskys already may

occur, there is no direct evidence of individuals

from one subpopulation dispersing to breed in

another, and genetic differences similarly reflect

a low degree of interaction. Nevertheless, the

potential exists for exchange between CRD and

island geese, and for recolonization after local

extirpation. As discussed earlier, the dusky subpopulations have common wintering grounds and

regionally adjacent nesting grounds. Nevertheless, dispersal, the key component of metapopulations, is difficult to study and rarely known

(Gutierrez and Harrison 1996, McCullough 1996,

Wiens 1996).

As a special case of metapopulations, CRD geese

apparently now compose a sink population,

where reproduction is insufficient to maintain
55

the population because of high local mortality.

In contrast, island geese, certainly from the

Middleton Island breeding site, are more productive and may be, or may become, a source population, where emigration potentially leads to

dispersal to the CRD population (Pulliam 1988).

Pulliam (1988) has suggested that this can occur

to such an extent in some species that sink populations can be maintained by source populations

over the long term. Because strategies enhancing population parameters in the natural population seem to be most effective when directed at

healthier subpopulations (Wootton and Bell

1992), studies and management of survival, productivity, and dispersal of island geese (a potential source population) may be warranted.

As a source population, island geese eventually

may contribute sufficient numbers of individuals

to sustain the CRD subpopulation. Ultimately, the

CRD population either will persist until it again

becomes a source by adapting to the new habitat

or when sufficient new salt marsh develops, or it

will dwindle and disappear. As natural restoration

of habitat occurs through processes described

earlier, however, the CRD population may be

reestablished through dispersal from the source

population until CRD geese can once again sustain themselves or even increase. In this process,

small, seemingly meaningless changes in rates of

dispersal, reproduction, and survival may gain

importance over time, eventually having significant implications to subpopulation dynamics. Regardless of which or to what degree each scenario

occurs, management will have the opportunity to

protect and enhance these natural interactions by

using knowledge of dispersal, interbreeding of

subpopulations, and survival and reproductive

rates by location over time.

Long-Term Outlook

The long-term cycle of dramatic uplift followed

by gradual subsidence of the CRD over intervals

of 600 to 950 years has been well documented

and indicates that a new iteration began with the

1964 earthquake. Although the short-term future

habitat conditions and associated high rates of

depredation on the CRD will be a challenge for

dusky Canada geese, the gradually developing

new marsh with eventual subsidence of the old

marsh and subsequent reversion to salt marsh

promise a more rewarding long-term prognosis

for duskys, at least on a geological time scale.

Boggs (2000) suggested that eventually there may

be a net increase in marsh habitat on the CRD

because the trend in past episodes has been for a

net gain in the total extent of salt marsh with each

cycle.

To take advantage of the eventual increase in

habitat, however, duskys must survive and remain

viable as a population over the long term, viewed

from the context of a human time scale. Longterm survival seems possible for several reasons.

For example, despite a modest population of possibly 2,000 birds, until the recent irruption of the

Middleton Island population, itself now about

2,000, island Canada geese have persisted over

time, indicating a population resiliency useful

under these conditions. There are also small

pockets of duskys (e.g., Bering Glacier area) that

persist in the absence of specially directed conservation effort.

One further example is the Vancouver Canada

goose, a largely nonmigratory race (Ratti and

Timm 1979) that occupies forest habitat and tidal

areas of southeastern Alaska. Geese of this race

nest in coastal temperate rain forests of Sitka

spruce, western hemlock (Tsuga heterophylla

(Raf.) Sarg.), and lodgepole pine (Pinus contorta

Dougl. ex Loud.). Nest sites are located in

heavily forested areas at the base of trees, on tree

stumps and snags, and even on moss-covered tree

limbs (Lebeda 1980, Lebeda and Ratti 1984, Ratti

in Timm and Havens 1973). Males use roost sites

on tree limbs far above the forest floor during

incubation, and both broods and molting geese

use forest as escape terrain when disturbed

(Lebeda and Ratti 1984). The principal food for

Vancouver Canada geese is American yellow

skunk cabbage (Lysichiton americanum Hult. &

St. John), a common plant in the understory. In

summary, this race of Canada geese has become

uniquely adapted to a forested environment. Although crows, ravens, bald eagles, river otters,

and brown bears are present, they typically frequent more open areas, leading Lebeda and Ratti

(1984) to speculate that dense forest vegetation
56

characteristic of nest sites decreased the vulnerability of these nests to predators, a condition not

available in the narrow fringes of traditional,

open habitat at the forest edge.

By remaining on their traditional nesting grounds

despite dramatic and rapid plant succession with

subsequent changes in the structure of vegetation,

dusky Canada geese are being forced to use increasingly shrubby and forested nesting habitat.

There may now be generations of duskys that

have only experienced this type of habitat, and

these geese may already be increasing their nesting range on the upper CRD, moving inland into

habitat similar to what now occurs on the traditional parts of their range. This may be how

Vancouver Canada geese evolved their nesting

and brood-rearing habits, if not on the CRD, then

at some similar location and situation in the geologically dynamic region of coastal Alaska. In

their forested habitat, an environment likely similar to that toward which the CRD is headed,

Vancouver Canada geese experienced 56 percent

nest success (Lebeda and Ratti 1984). Although

measured only 1 year, this rate of success is much

higher than the rate duskys now normally experience. Thus, the persistence and viability of their

population and their unique adaptations make

Vancouvers a positive example of one possible

direction for the long-term future of duskys.

In contrast, as the nesting and brood-rearing habitat of duskys continues to become less suitable as

succession proceeds, the population may decline

gradually if they are not able to adapt. Given a

rapid invasion of Sitka spruce and cottonwoods

on the nesting grounds, and the presence of abundant potential prey during spring and summer,

bald eagles can be expected to respond by establishing a high density of nest sites. Nest success

of geese and survival of nesting adults might decline. Thus, for geese, the presently low rate of

recruitment would decline further, while population mortality rates may remain at their present

levels, or even increase, leading to a net loss to

the population. If minimal annual recruitment

consistently occurs over time, the average age of

surviving adults would increase, with an eventual

drop in reproductive potential. At some point, an

abrupt decline would likely occur. To prevent or

mitigate this scenario, efforts are warranted to

promote high adult survival rates, and to support

successful reproduction to the extent feasible.

Knowledge Gaps and Information Needs—Relationship to

Management

As indicated in the annotated bibliography of

work on dusky geese (Campbell and Cornely

1992), there is a substantial body of research and

survey information on these birds, and much of it

has been incorporated directly into management

programs. The Pacific Flyway management plan

details the current management and research procedures to be implemented at three action levels

tied to dusky goose population size estimated

from the CRD and Middleton Island (Pacific Flyway Council 1997). As a result of this biological

review, the following topics are mentioned to

supplement or underscore the planned procedures

in the flyway plan, and most are specifically directed toward the CRD subpopulation, or to sorting out subpopulations. Also, a few of the items

highlighted below are actually next-step suggestions flowing logically from progress already

achieved on initiatives listed in the plan. The

following recommendations, therefore, should

not be viewed as an exhaustive list of information

needed for the routine management of duskys; for

this, the flyway plan should be consulted.

Taxonomy and Classification

The recent progress of research in the field of

genetics has been great but has created dilemmas

for wildlife managers. Although differences between many species and subspecies are clear, in

species such as the Canada goose there are now

easily detected but often minor genetic differences between groups of breeding birds that are

only modestly separated geographically or evolutionarily. The situation with dusky Canada geese

provides a typical example. As recommended

in the flyway management plan, considerable

work has been conducted to elucidate relations

between populations of Canada geese in the

Pacific Flyway (e.g., Pearce et al. 1998, Shields

and Connor 1998), and more work is ongoing.
57

Because of the close relationships among groups

of Canada geese breeding in southern Alaska and

coastal British Columbia, and because of the

large body of new information both accumulated

and pending, a coordinated and joint review of

the current taxonomic designations of breeding

groups by both researchers and managers in the

near future will help to appropriately delineate

populations for uniquely focused management

attention.

Distribution

Despite extensive knowledge within the CRD,

western Oregon, and southwestern Washington,

little is known of the numbers and locations of

duskys wintering in British Columbia. These

geese are not currently included in annual midwinter population estimates. The degree to which

these birds represent a segment of the population

associated with a particular part of the breeding

grounds, and variation in the size of this segment

are unknown. Characteristics of migration remain

even less understood. The exact migration route

duskys take to and from their wintering grounds,

the habitats they use, and when and to what extent they use them remain poorly understood.

Breeding Population Estimates

Because of the rapidly increasing and changing

numbers of similar-looking Canada geese on the

wintering grounds, and the problems this presents

for developing reliable population estimates of

duskys, the value of a method to reliably estimate

breeding population size is greatly elevated.

Breeding population estimates currently constitute indices, rather than absolute numbers, because they are uncorrected for visibility bias. This

problem is confounded by the inconsistent results

obtained during assessment of visibility bias

when using helicopters. Possible sources of this

inconsistency are the changing nature of the environment caused by accelerated plant succession

and the relatively dense cover now occurring on

the CRD. Expansion of aerial survey estimates

with factors derived from nest densities (Stehn

1991) seems to hold the most promise. For

duskys, this method is complicated by the unknown and variable extent of annual renesting

that occurs. The degree of renesting and the

causes of renesting need to be assessed carefully

before they are incorporated into estimations of

the breeding population.

Exchange Between Copper River

Delta Geese and Island Geese

As a metapopulation, there is some chance that

the CRD subpopulation of duskys will be supported by dispersal from island geese, and that

CRD duskys will contribute, at least genetically,

to island geese. Although exchange is now apparently low, over time any dispersal phenomena

that lead to greater reproductive success and survival beyond what would have occurred without

dispersal will be magnified. Dispersal may be

occurring because CRD geese and island geese

winter sympatrically and nest in adjacent regions.

Dispersal could assist the long-term viability of

duskys, ensuring either the persistence of geese

on the CRD or the eventual recolonization of the

CRD after favorable habitat conditions are naturally restored. To enhance this potential, managers should attempt to detect and measure

dispersal between subpopulations, and be prepared to take management action to protect this

exchange and the potential for increased productivity and survival of duskys that may result. Because island geese may be an important source

population, a wise course would be to determine

monitoring and management needs for ensuring

their conservation over the long term. If numbers

of CRD geese become critically low, consideration could be given to transplanting island geese

from forested locations to the CRD.

Population Age Structure

The reproductive potential of a population is

higher with a majority of young to middle-aged

adults than with a population consisting largely of

old adult birds. Relatively low recruitment rates

have now characterized the dusky Canada goose

population for about 20 years. Adult survival has

been high for at least 15 years. To be able to predict the future prospects for the population, and

to be prepared for management needs as they

arise, the age structure of the population is an
58

important component that needs to be evaluated.

Given the active banding program that has been

conducted with the dusky population for many

years, and given the ongoing commitment to

regular banding quotas at certain intervals, data

may be already in hand to assess aging of the

population.

Depredation

Knowledge of the predators that currently are

responsible for loss of eggs, nesting adults, and

goslings on the breeding grounds is required.

Real data on this question are extremely difficult

to accumulate yet may be essential should there

be periods when management is needed to boost

nest success. Answers to related questions, such

as when and where does depredation occur and

not occur, and what conditions influence the degree of depredation, will lead to both further understanding of potential management options and

effective use of advantageous opportunities.

Depending on the successional stage on the nesting grounds, the species, effectiveness of depredation, and population status of predators will

vary. For bald eagles, knowledge of their rate of

colonization for nesting, their hunting range, and

their proclivity for duskys and eggs is needed.

Their efficiency of depredation may differ by

habitat type.

Further, the relation of the eulachon run to the

degree and timing of nest depredation, when the

spring eulachon run occurs in relation to the timing of nesting by geese, and whether the factors

influencing the timing and size of the run are the

same as those influencing spring phenology and

associated nesting chronology of geese require

elucidation. Perhaps the presence of eulachon

buffers geese from depredation, or increases depredation by attracting predators to the nesting

grounds.

Finally, evidence indicates that high nest loss

occurs early in the nesting period and declines

steeply during late nesting. Proactive, small-scale

testing of techniques to control nest depredation

during this narrow window of time deserves consideration, and should be considered during

brood-rearing if appropriate.

Adult Mortality on Nesting Grounds

Knowledge of mortality rates of breeding adults

by phase of reproduction is key to understanding

limitations to production, and for directing management initiatives. Current research includes

assessing predators responsible for adult mortality during nesting, and for determining adult and

gosling mortality during brood-rearing. However,

a quantitative assessment of mortality rates of

breeding adults before and during nesting will

help ensure effective use of management effort.

Why Is Use of Artificial Nesting

Islands So Low?

The current annual use of less than 30 percent of

artificial nest islands by duskys is much lower

than is typical of Canada geese elsewhere in

North America. Understanding whether this is

attributable to unique habits of dusky geese, characteristics of the structures, or other environmental factors is important to increase the potential

contribution of artificial islands to production, or

at least allow a thorough evaluation of the program.

Quality of Breeding Habitat Given

Accelerated Plant Succession

Duskys typically arrive on their breeding grounds

and feed vigorously to increase their nutritional

condition and to form eggs during the prelaying

and laying period. Because habitat changes have

been extreme, however, it is unknown if sufficient quantity and quality of habitat exists for

duskys to meet their energy and nutritional

requirements for reproduction at a rate similar

to that of the past. Comparison of clutch size in

recent years to data from earlier times may shed

some light here. Similarly, comparison of constancy of incubation and frequency and duration of recesses between contemporary and past

periods would be useful. At the higher survival

rates typical of adult geese in the near absence of

hunting, they may maintain sufficient reproductive potential for population maintenance. This

potential, however, may be much lower than it

was when higher quality habitat existed 10 to 30

years ago.
59

New Marsh Development and Old

Marsh Plant Succession

The rate of new marsh development has been

monitored, and this monitoring should be continued. Monitoring also should include a periodic

assessment of the use of, and productivity in, the

new marsh by duskys. To develop a predictive

capability for long-term assessment, however, the

rates of subsidence and silt deposition (and accretion) need to be determined. Knowing these rates

will improve the ability of land managers to predict rates of new marsh expansion and changes in

the rate, timing, and direction of plant succession

on the delta.

Winter Foraging Ecology

Because of the increasing numbers of other

Canada geese wintering sympatrically with

duskys, there remains a need for detailed information on the winter foraging ecology of this

race. The carrying capacity of the Willamette

Valley for Canada geese is being approached, at

least in terms of human tolerance to geese. As

crop depredation complaints and the overall density of geese increase, new pressures will be

brought to bear on duskys. These include conversion of grassland foraging habitat to pulpwood

production (Fleagle 1991) and other uses, hazing

from croplands and redistribution to other habitats, as well as proposals to expand hunting to

move or reduce goose populations. Detailed insights on foraging characteristics and needs of

duskys in this changing environment will support

the effectiveness of management efforts to meet

their requirements and ensure that they reach

ideal physiological condition before spring migration and the onset of reproduction.

Acknowledgments

This review would not have been possible without the cooperation of migratory bird personnel

of all sponsoring agencies, especially members

of the Dusky Canada Goose Subcommittee of the

Pacific Flyway Study Committee. In particular,

we thank those who permitted personal communications and provided unpublished reports, early

results, and preliminary conclusions of ongoing

studies. We have gained a special appreciation

for all of the management and research personnel,

past and present, who have dedicated their time

to understanding the dusky Canada goose and

its ever-changing ecology. Thanks to Belle

Mickelson of Cordova and Bob Jarvis of

Corvallis for their personal hospitality to RGB

during stays at their homes; Dan Logan and Don

Youkey helped RGB make his brief time on the

CRD productive. This assessment has benefited

from reviews by Robert Jarvis, Richard Malecki,

and an anonymous reviewer. We thank Terry

Shaw for facilitation of the peer review and

editorial advice through the USDA Forest

Service, Pacific Northwest Research Station in

Juneau, Alaska; David Brooks then at USDA

Forest Service, Pacific Northwest Research Station in Corvallis, Oregon, for arranging final editing; and Lynn Starr of USDA Forest Service,

Pacific Northwest Research Station, Portland,

Oregon, for diligent attention to manuscript details. Editorial services and publication of this

report were provided through generous contributions by the USDA Forest Service, Chugach National Forest and the Pacific Northwest Research

Station.

English Equivalents

When you know: Multiply by: To find:

Millimeters (mm) 0.0394 Inches

Centimeters (cm) .394 Inches

Meters (m) 3.28 Feet

Square meters (m2

) 10.76 Square feet

Kilometers (km) .6215 Miles

Hectares (ha) 2.471 Acres

Square kilometers (km2) .386 Square miles

Kilograms (kg) 2.205 Pounds
60

References

Anonymous. 1986. Summary of observations on dusky Canada geese, Willapa Bay, winter of 1985-

1986. Unpublished report. 2 p. On file with: USDI Fish and Wildlife Service, Willapa Bay National

Wildlife Refuge Complex, 3888 SR 101, Ilwaco, WA 98624.

Alaska Department of Fish and Game [ADFG]. 1999. Unpublished data on neck collar observations

and radio telemetry locations of Canada geese marked on Green and Middleton Islands and

documented in western Oregon during winter 1998-1999. On file with: Alaska Department of Fish

and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Alaska Department of Fish and Game [ADFG]. 2000. Unpublished harvest database for big game,

including brown bears. On file with: Alaska Department of Fish and Game, Division of Wildlife

Conservation, 333 Raspberry Road, Anchorage, AK 99518.

Aldrich, J.W. 1946. Speciation in white-cheeked geese. Wilson Bulletin. 58(2): 94-103.

American Ornithologists’ Union [AOU]. 1910. Check-list of North American birds. 3rd ed.

New York. 430 p.

American Ornithologists’ Union [AOU]. 1957. Check-list of North American birds. 5th ed.

Baltimore, MD: Port City Press. 691 p.

American Ornithologists’ Union [AOU]. 1983. Check-list of North American birds. 6th ed.

Lawrence, KS: Allen Press. 877 p.

Annear, J. 1976 (21 April). Letter to D.E. Timm. On file with: Alaska Department of Fish and Game,

525 West 67th Avenue, Anchorage, AK 99518.

Anthony, A.W. 1886. Field notes on the birds of Washington County, Oregon. Auk. 3: 161-172.

Atkinson, J.B. 1987. Distribution and abundance of migrating and wintering Canada geese at Willapa

Bay, Washington from September 1986 through April 1987. Unpublished report. 11 p. On file with:

USDI Fish and Wildlife Service, Willapa Bay National Wildlife Refuge Complex, 3888 SR 101,

Ilwaco, WA 98624.

Atkinson, J.B. 1988. Distribution and abundance of migrating and wintering Canada geese at Willapa

Bay, Washington from September 1987 through May 1988. Unpublished report. 8 p. On file with:

USDI Fish and Wildlife Service, Willapa Bay National Wildlife Refuge Complex, 3888 SR 101,

Ilwaco, WA 98624.

Atkinson, J.B. 1989. Distribution and abundance of migrating and wintering Canada geese at Willapa

Bay, Washington from October 1988 through April 1989. Unpublished report. 9 p. On file with:

USDI Fish and Wildlife Service, Willapa Bay National Wildlife Refuge Complex, 3888 SR 101,

Ilwaco, WA 98624.

Atkinson, J.B. 1990. Distribution and abundance of migrating and wintering Canada geese at Willapa

Bay, Washington from October 1989 through April 1990. Unpublished report. 10 p. On file with:

USDI Fish and Wildlife Service, Willapa Bay National Wildlife Refuge Complex, 3888 SR 101,

Ilwaco, WA 98624.

Atkinson, J.B. 1991. Distribution and abundance of migrating and wintering Canada geese at Willapa

Bay, Washington from October 1990 through April 1991. Unpublished report. 10 p. On file with:

USDI Fish and Wildlife Service, Willapa Bay National Wildlife Refuge Complex, 3888 SR 101,

Ilwaco, WA 98624.
61

Atkinson, J.B. 1992. Distribution and abundance of migrating and wintering Canada geese at Willapa

Bay, Washington from October 1991 through April 1992. Unpublished report. 10 p. On file with:

USDI Fish and Wildlife Service, Willapa Bay National Wildlife Refuge Complex, 3888 SR 101,

Ilwaco, WA 98624.

Babler, S. 1999. Personal communication. Wildlife biologist, USDA Forest Service, P.O. Box 280,

Cordova, AK 99574.

Babler, S.; Youkey, D.; Crouse, J.A. 1998. Eleven years of artificial nest islands for dusky Canada

geese on the Copper River Delta, Alaska. Unpublished report. 36 p. On file with: USDA Forest

Service, P.O. Box 280, Cordova, AK 99574.

Bailey, A.M. 1927. Notes on the birds of southeastern Alaska. Auk. 44: 1-23, 184-205, 351-367.

Baird, S.F. 1858. Reports of explorations and surveys to ascertain the most practical and economical

route for a railroad from the Mississippi River to the Pacific Ocean. In: Vol. IX, Birds. Washington,

DC: United States Senate Ex. Doc. No. 78. B. Tucker, printer: 765-766.

Baird, S.F.; Brewer, T.M.; Ridgeway, R. 1884. The waterbirds of North America. Vol. 1. Memoirs

of the Museum of Comparative Zoology, Harvard College. 12: 1-537.

Banks, R.C. 1992 (16 April). Memo to Chief, Office of Migratory Bird Management. Subspecies of

Canada geese. On file with: USDI Fish and Wildlife Service, 4401 North Fairfax Drive, Arlington,

VA 22203.

Bellrose, F.C. 1986. Ducks, geese, and swans of North America. Harrisburg, PA: Stackpole Books.

540 p.

Bernatowitz, J.A.; Bowman, T.D.; Schempf, P.F. [In press]. Seasonal and regional movements of

radio-tagged bald eagles from Prince William Sound, Alaska. In: Wright, B.; Schempf, P., eds. Bald

eagles in Alaska. Juneau, AK: American Bald Eagle Institute.

Bernatowitz, J.A.; Schempf, P.F.; Bowman, T.D. 1996. Bald eagle productivity in south-central

Alaska in 1989 and 1990 after the Exxon Valdez oil spill. American Fisheries Society Symposium.

18: 785-797.

Boggs, K. 2000. Classification of community types, successional sequences and landscapes of the

Copper River Delta, Alaska. Gen. Tech. Rep. PNW-GTR-469. Portland, OR: U.S. Department of

Agriculture, Forest Service, Pacific Northwest Research Station. 244 p.

Bowman, T.D. 1999. Personal communication. Wildlife biologist, USDI Fish and Wildlife Service,

Migratory Bird Management, 1011 East Tudor Road, Anchorage, AK 99503.

Bowman, T.D.; Schempf, P.F.; Bernatowitz, J.A. 1995. Bald eagle survival and population

dynamics in Alaska after the Exxon Valdez oil spill. Journal of Wildlife Management. 59(2):

317-324.

Bowman, T.D.; Schempf, P.F.; Hodges, J.I. 1997. Bald eagle population in Prince William Sound

after the Exxon Valdez oil spill. Journal of Wildlife Management. 61(3): 962-967.

Bromley, R.G.H. 1976. Nesting and habitat studies of the dusky Canada goose (Branta canadensis

occidentalis) on the Copper River Delta, Alaska. Fairbanks, AK: University of Alaska. 81 p. M.S.

thesis.
62

Bromley, R.G.H. 1979. Unpublished data on dusky Canada geese nesting on the Copper River

Delta, 1977-79. On file with: Whole Arctic Consulting, P.O. Box 1177, Yellowknife, NT, Canada

X1A 2N8.

Bromley, R.G.H. 1981. Analysis of dusky Canada goose body weights on the wintering grounds—

mid-1960s to mid-1970s. Unpublished report. 15 p. On file with: Department of Fisheries and

Wildlife, Nash Hall, Oregon State University, Corvallis, OR 97331.

Bromley, R.G.H. 1984. The energetics of migration and reproduction of dusky Canada geese (Branta

canadensis occidentalis). Corvallis, OR: Oregon State University. 116 p. Ph.D. dissertation.

Bromley, R.G.H.; Heard, D.C.; Croft, B. 1995. Visibility bias in aerial surveys relating to nest

success of Arctic geese. Journal of Wildlife Management. 59(2): 364-371.

Bromley, R.G.H; Jarvis, R.L. 1993. The energetics of migration and reproduction of dusky Canada

geese. Condor. 95(1): 193-210.

Brooks, A. 1917. Birds of the Chilliwach District, B.C. Auk. 34: 28-50.

Brooks, A. 1923. Notes on the birds of Porcher Island, B.C. Auk. 40: 217-224.

Buchholz, W.G.; Pearce, J. M.; Pierson, B.J.; Scribner, K.T. 1998. Dinucleotide repeat

polymorphisms in waterfowl (family Anatidae): characterization of a sex-linked (Z-specific) and 14

autosomal loci. Animal Genetics. 29: 1-2.

Butler, W.L. 1986. Preliminary progress report on the development of aerial survey procedures for

dusky Canada geese (DCG) nesting on the Copper River Delta for the July Pacific Flyway Study

Committee meetings. Unpublished report. 2 p. On file with: USDI Fish and Wildlife Service, 1011

East Tudor Road, Anchorage, AK 99503.

Butler, W.L. 1987. Preliminary progress report on the development of aerial survey procedures for

dusky Canada geese (DCG) nesting on the Copper River Delta for the July Pacific Flyway Study

Committee meetings. Unpublished report. 3 p. On file with: USDI Fish and Wildlife Service, 1011

East Tudor Road, Anchorage, AK 99503.

Butler, W.L. 1988. Report to Pacific Flyway Study Committee on breeding pair survey for dusky

Canada geese on the Copper River Delta. Unpublished report. 3 p. On file with: USDI Fish and

Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.

Butler, W.L. 1989. Report to Pacific Flyway Study Committee on breeding pair survey for dusky

Canada geese on the Copper River Delta. Unpublished report. 4 p. On file with: USDI Fish and

Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.

Butler, W.L. 1990. Report to Pacific Flyway Study Committee on breeding pair survey for dusky

Canada geese on the Copper River Delta. Unpublished report. 5 p. On file with: USDI Fish and

Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.

Butler, W.L. 1991. Report to Pacific Flyway Study Committee on 1986-1991 breeding ground surveys

of dusky Canada geese on the Copper River Delta. Unpublished report. 4 p. On file with: USDI Fish

and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.

Butler, W.L. 1992. Report to Pacific Flyway Study Committee on 1986-1992 breeding ground surveys

of dusky Canada geese on the Copper River Delta. Unpublished report. 6 p. On file with USDI Fish

and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.
63

Butler, W.L. 1993. Report to Pacific Flyway Study Committee on 1986-1993 breeding ground surveys

of dusky Canada geese on the Copper River Delta. Unpublished report. 4 p. On file with: USDI Fish

and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.

Butler, W.L. 1994. Report to Pacific Flyway Study Committee on 1986-1994 breeding ground surveys

of dusky Canada geese on the Copper River Delta. Unpublished report. 4 p. On file with: USDI Fish

and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.

Butler, W.L.; Crouse, J.A.; Stehn, R.; Eldridge, W.D. 1995. Nest numbers and aerial surveys:

management tools for monitoring dusky Canada geese. In: Abstracts of 8th North American Arctic

Goose Conference; 1995 January; Albuquerque, NM. 35 p. On file with: Alaska Department of Fish

and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Butler, W.L.; Eldridge, W.D. 1991. Development of an aerial breeding pair survey for dusky Canada

geese (Branta canadensis occidentalis) on the Copper River Delta, Alaska: final report.

Unpublished report. 30 p. On file with: USDI Fish and Wildlife Service, 1011 East Tudor Road,

Anchorage, AK 99503.

Campbell, B.H. 1984. Annual report of survey-inventory activities. Part V. Waterfowl. Fed. Aid

Wildl. Rest. Prog. Report. Proj. W-22-2, Job 11. Juneau, AK: Alaska Department of Fish and Game.

29 p. Vol. XIV.

Campbell, B.H. 1987. Memorandum: Middleton Island trip report, June 18, 1987, to Waterfowl

Coordinator. 3 p. + figures. On file with: Alaska Department of Fish and Game, 525 West 67th

Avenue, Anchorage, AK 99518.

Campbell, B.H. 1988. Habitat availability, utilization, and nesting success of dusky Canada geese on

the Copper River Delta, Alaska. Unpublished report. 45 p. On file with: Alaska Department of Fish

and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Campbell, B.H. 1990a. Annual waterfowl program progress report. Unpublished report. 41 p. On file

with: Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Campbell, B.H. 1990b. Factors affecting the nesting success of dusky Canada geese, Branta

canadensis occidentalis, on the Copper River Delta, Alaska. Canadian Field Naturalist.

104: 567-574.

Campbell, B.H. 1991a. Activities of brown bears on the Copper River Delta, Alaska and their impact

on nesting dusky Canada geese. Northwestern Naturalist. 72: 92-99.

Campbell, B.H. 1991b. Longevity records for the dusky Canada goose (Branta canadensis

occidentalis). Northwestern Naturalist. 72: 34-45.

Campbell, B.H. 1991c. Waterfowl program annual report. Unpublished report. 35 p. On file with:

Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Campbell, B.H. 1992a. Dusky Canada goose production, 1992. Unpublished report. 7 p. On file with:

Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Campbell, B.H. 1992b. Recent changes in production and population trends of the dusky Canada

goose. In: Abstracts of the 7th North American Arctic Goose Conference; 1992 January; Vallejo,

CA: 39. On file with: Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage,

AK 99518.
64

Campbell, B.H. 1999. Homing of translocated brown bears (Ursus arctos) in coastal south-central

Alaska. Northwestern Naturalist. 80: 22-25.

Campbell, B.H.; Becker, E.F. 1991. Neck collar retention in dusky Canada geese. Journal of Field

Ornithology. 62(4): 521-527.

Campbell, B.H.; Cornely, J.E. 1992. Dusky Canada goose: an annotated bibliography. Resource

Publication 187. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 30 p.

Campbell, B.H.; Griese, H.J. 1987. Management options for dusky Canada geese and their predators

on the Copper River Delta, Alaska. Unpublished report. 91 p. On file with: Alaska Department of

Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Campbell, B.H.; Rosenberg, D.H.; Rothe, T.C. 1987. Annual report of survey and inventory

activities—waterfowl. Part XIII. Fed. Aid Wildl. Rest. Proj. W-22-5, Job 11. Juneau, AK: Alaska

Department of Fish and Game. 55 p. Vol. XVII.

Campbell, B.H.; Rosenberg, D.H.; Rothe, T.C. 1988. Annual report of survey and inventory

activities—waterfowl. Part XIII. Fed. Aid Wildl. Rest. Proj. W-22-6, Job 11. Juneau, AK: Alaska

Department of Fish and Game. 75 p. Vol. XVIII.

Campbell, B.H.; Rosenberg, D.H.; Rothe, T.C. 1992. Waterfowl program annual report.

Unpublished report. 43 p. On file with: Alaska Department of Fish and Game, 525 West 67th

Avenue, Anchorage, AK 99518.

Campbell, B.H.; Rothe, T.C. 1985. Annual report of survey and inventory activities—waterfowl

 Part XIII. Fed. Aid Wildl. Rest. Proj. W-22-3, Job 11. Juneau, AK: Alaska Department of Fish

and Game. 31 p. Vol. XIX.

Campbell, B.H.; Rothe, T.C. 1986. Annual report of survey and inventory activities—waterfowl

 Part XIII. Fed. Aid Wildl. Rest. Proj. W-22-4, Job 11. Juneau, AK: Alaska Department of Fish

and Game. 36 p. Vol. XVI.

Campbell, B.H.; Rothe, T.C. 1989. Annual report of survey and inventory activities—waterfowl

 Part XIII. Fed. Aid Wildl. Rest. Proj. W-23-1, Study 11. Juneau, AK: Alaska Department of Fish

and Game. 42 p. Vol. XIX.

Campbell, B.H.; Rothe, T.C. 1990. Annual report of survey and inventory activities—waterfowl

 Part XIII. Fed. Aid Wildl. Rest. Proj. W-23-2, Study 11. Juneau, AK: Alaska Department of Fish

and Game. 42 p. Vol. XX.

Campbell, B.H.; Timm, D.E. 1983. Annual report of survey-inventory activities. Part V. Waterfowl.

Fed. Aid Wildl. Rest. Prog. Report. Proj. W-22-1, Job 11. Juneau, AK: Alaska Department of Fish

and Game. 45 p. Vol. XIII.

Carnes, J.C.; Van Ballenberghe, V.; Peek, J.M. 1996. Ecology of wolves on the Copper and Bering

River Deltas, Alaska. Unpublished report. 46 p. On file with: USDA Forest Service, Pacific Northwest Research Station, 3301 C Street, Suite 200, Anchorage, AK 99503.

Chapman, D.G. 1951. Some properties of the hypergeometric distribution with applications to

zoological censuses. University of California Publications in Statistics. 1: 131-160.

Chapman, J.A. 1970. Weights and measurements of dusky Canada geese wintering in Oregon.

Murrelet. 51(3): 34-37.
65

Chapman, J.A.; Henny, C.J.; Wight, H.M. 1969. The status, population dynamics, and harvest of the

dusky Canada goose. Wildlife Monographs. 18: 1-48.

Clark, S.L.; Jarvis, R.L. 1978. Effects of winter grazing by geese on yield of ryegrass seed. Wildlife

Society Bulletin. 6(2): 84-87.

Conant, B.; Dau, C.P. 1989. Dusky Canada goose breeding population survey. Unpublished report.

 4 p. On file with: USDI Fish and Wildlife Service, 3000 Vintage Boulevard, Suite 200, Juneau,

AK 99801.

Conant, B.; Dau, C.P. 1990. Dusky Canada goose breeding population survey. Unpublished report.

 4 p. On file with: USDI Fish and Wildlife Service, 3000 Vintage Boulevard, Suite 200, Juneau,

AK 99801.

Conant, B.; Hodges, J. 1986. Dusky Canada goose breeding population survey. Unpublished report.

 4 p. On file with: USDI Fish and Wildlife Service, 3000 Vintage Boulevard, Suite 200, Juneau,

AK 99801.

Cornely, J.E.; Campbell, B.H.; Jarvis, R.L. 1985. Productivity, mortality, and status of dusky

Canada geese. Transactions of the North American Wildlife and Natural Resources Conference.

50: 540-548.

Cornely, J.E.; Jarvis, R.L. 1984. Status of Canada geese wintering in western Oregon and southwestern Washington. Unpublished report. 8 p. On file with: Department of Fisheries and Wildlife,

Nash Hall, Oregon State University, Corvallis, OR 97331.

Cornely, J.E.; Jarvis, R.L. 1985. Status of Canada geese wintering in western Oregon and southwestern Washington. Unpublished report. 7 p. On file with: Department of Fisheries and Wildlife,

Nash Hall, Oregon State University, Corvallis, OR 97331.

Cornely, J.E.; Jarvis, R.L.; Hills, M.R. 1986. Status of Canada geese wintering in western Oregon

and southwestern Washington. Unpublished report. 5 p. On file with: Department of Fisheries and

Wildlife, Nash Hall, Oregon State University, Corvallis, OR 97331.

Cornely, J.E.; Naughton, M.B.; Hills, M.R.; Raftery, K.M. 1998. Distribution of wintering dusky

and cackling Canada geese in western Oregon and western Washington, 1985-1989. In: Rusch,

D.H.; Samuel, M.D.; Humburg, D.D.; Sullivan, B.D., eds. Biology and management of Canada

geese: Proceedings of the International Canada Goose Symposium. Middleton, WI: Marler

Graphics: 221-229.

Crouse, J. 1994a. The distribution of migrating Canada geese on the Copper and Bering River Deltas

during the spring and fall of 1992. Unpublished report. 5 p. On file with: USDA Forest Service,

P.O. Box 280, Cordova, AK 99574.

Crouse, J. 1994b. Dusky Canada goose nest distribution and abundance on the Copper River Delta,

Alaska (1993). Unpublished report. 9 p. On file with: USDA Forest Service, P.O. Box 280,

Cordova, AK 99574.

Crouse, J. 1995. Dusky Canada goose nest distribution and abundance on the Copper River Delta,

Alaska (1994). Unpublished report. 11 p. On file with: USDA Forest Service, P.O. Box 280,

Cordova, AK 99574.

Crouse, J.; Youkey, D.; Babler, S. 1995. Dusky Canada goose nest distribution and abundance on the

Copper River Delta, Alaska (progress report 1995). Unpublished report. 11 p. On file with: USDA

Forest Service, P.O. Box 280, Cordova, AK 99574.
66

Crouse, J.; Youkey, D.; Babler, S. 1997. Dusky Canada goose nest distribution and abundance on

the Copper River Delta, Alaska (1993-1995). Unpublished report. 23 p. On file with: USDA Forest

Service, P.O. Box 280, Cordova, AK 99574.

Crow, J.H. 1968. Some effects of the March 27, 1964 earthquake on the ecology of the Copper River

Delta, Alaska. In: Shepherd, P.E.K; Hilliker, B.; Crow, J.H. Waterfowl report. Fed. Aid Wildl. Rest.

Prog. Report. Proj. W-13-R-2 and 3, Work Plan C. Juneau, AK: Alaska Department of Fish and

Game: 24-34. Vol. IX.

Crow, J.H. 1971. Earthquake-initiated changes in the nesting habitat of the dusky Canada goose. In:

The great Alaska earthquake of 1964: biology. Washington, DC: National Academy of Sciences:

30-136.

Crowley, D. 1998. Status of the urban population of Canada geese in Anchorage, Alaska—1998.

Unpublished report. 11 p. On file with: Alaska Department of Fish and Game, 525 West 67th

Avenue, Anchorage, AK 99518.

Crowley, D. 1999a. Personal communication. Area wildlife biologist, Alaska Department of Fish

and Game, P.O. Box 669, Cordova, AK 99574.

Crowley, D. 1999b. Unit 6 Prince William Sound and North Gulf Coast. In: Hicks, M.V., ed.

Management report of survey—inventory activities: brown bear. Fed. Aid Wildl. Rest. Grants

W-24-5 and W-27-1. Juneau, AK: Alaska Department of Fish and Game: 36-54.

Crowley, D.; Petrula, M. 1998. Unpublished data from Canada goose nest surveys of Green and

Middleton Islands. On file with: Alaska Department of Fish and Game, 525 West 67th Avenue,

Anchorage, AK 99518.

Crowley, D.; Petrula, M.; Rothe, T.C. [et al.]. 1998. Marking Canada geese on the North Gulf Coast

of Alaska—1998. Unpublished report. 5 p. On file with: Alaska Department of Fish and Game, 525

West 67th Avenue, Anchorage, AK 99518.

Crowley, D.; Rosenberg, D.H.; Petrula, M.; Rothe, T.C. 1997. Middleton Island Canada geese: a

status report. Unpublished report. 8 p. On file with: Alaska Department of Fish and Game, 525 West

67th Avenue, Anchorage, AK 99518.

Darrow, R. 1938. Possibilities of recognizing the evidence of depredation and the species involved in

the remains of grouse and grouse nests found destroyed. Transactions of the North American Wildlife Conference. 3: 834-838.

Dawson, W.L. 1909. The birds of Washington. Seattle, WA: Occidental Publication Co. 997 p.

Delacour, J. 1951. Preliminary note on the taxonomy of Canada geese, Branta canadensis. American

Museum Novitiates. 1537: 1-10.

Delacour, J. 1954. The waterfowl of the world. London: Country Life Limited. 284 p. Vol. 1.

Dickinson, J.C. 1953. Report on the McCabe collection of British Columbia birds. Bulletin of the

Museum of Comparative Zoology, Harvard College. 109: 123-209.

Dixon, J. 1908. Field notes from Alaska. Condor. 10: 139-143.

Drent, R.H. 1973. The natural history of incubation. In: Farner, D.S., ed. Breeding biology of birds.

Washington, DC: National Academy of Sciences: 262-311.

Drut, M.S.; Trost, R.E. 1999. Estimated number of dusky Canada geese, January 1999. Unpublished

report. 3 p. On file with: USDI Fish and Wildlife Service, 911 NE 11th Avenue, Portland, OR 97232.
67

Drut, M.S.; Trost, R.E. 2003. Estimated number of dusky Canada geese, January 2003. Unpublished

report. 4 p. On file with: USDI Fish and Wildlife Service, 911 NE 11th Avenue, Portland, OR 97232.

Drut, M.S.; Trost, R.E.; Naughton, M. 1997. Estimated number of dusky Canada geese, January

1997. Unpublished report. 4 p. On file with: USDI Fish and Wildlife Service, 911 NE 11th Avenue,

Portland, OR 97232.

Drut, M.S.; Trost, R.E.; Naughton, M. 1998. Estimated number of dusky Canada geese, January

1998. Unpublished report. 3 p. On file with: USDI Fish and Wildlife Service, 911 NE 11th Avenue,

Portland, OR 97232.

Eldridge, W.D.; Dau, C.P. 2002. Report to the Pacific Flyway Study Committee on 1986-2002

breeding ground survey preliminary results for dusky Canada geese on the Copper River Delta,

Alaska. Unpublished report. 6 p. On file with: USDI Fish and Wildlife Service, 1011 East Tudor

Road, Anchorage, AK 99503.

Eldridge, W.D.; Platte, R. 1995. Report to the Pacific Flyway Study Committee on 1986-1995

breeding ground surveys of dusky Canada geese on the Copper River Delta. Unpublished report.

9 p. On file with: USDI Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.

Eldridge, W.D.; Platte, R. 1996. Report to the Pacific Flyway Study Committee on 1986-1996

breeding ground surveys of dusky Canada geese on the Copper River Delta. Unpublished report.

6 p. On file with: USDI Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.

Eldridge, W.D.; Platte, R.; Dau, C.P.; Larned, W. 1998. Report to the Pacific Flyway Study

Committee on 1986-1998 breeding ground surveys of dusky Canada geese on the Copper River

Delta. Unpublished report. 6 p. On file with: USDI Fish and Wildlife Service, 1011 East Tudor

Road, Anchorage, AK 99503.

Eldridge, W.D.; Platte, R.; Larned, W. 1997. Report to the Pacific Flyway Study Committee on

1986-1997 breeding ground surveys of dusky Canada geese on the Copper River Delta. Unpublished report. 11 p. On file with: USDI Fish and Wildlife Service, 1011 East Tudor Road,

Anchorage, AK 99503.

Elkins, W.A. 1952. Alaska Pacific Flyway report. In: Pacific Flyway Waterfowl Report, No. 20.

Juneau, AK: Bureau of Sport Fisheries and Wildlife: A-7.

Ely, C.R.; Scribner, K.T. 1994. Genetic diversity in arctic-nesting geese: implications for management and conservation. Transactions of the North American Wildlife and Natural Resources

Conference. 59: 91-110.

Eriksson, O. 1996. Regional dynamics of plants: a review of evidence for remnant, source-sink and

metapopulations. Oikos. 77: 248-258.

Fleagle, M. 1991. Cottonwood harvest. Seattle, WA: Horizon Air Magazine. March: 5.

Frair, J.; Liska, K. 1998. Dusky Canada goose observations and nest search results—Bering Glacier

Islands, 26-29 May 1998. Unpublished report. 7 p. On file with: USDI Bureau of Land Management, 222 West 7th Avenue, Anchorage, AK 99513.

Fredrickson, L.H.; Taylor, T.S. 1982. Management of seasonally flooded impoundments for wildlife. Resource Publication 148. Washington, DC: U.S. Department of the Interior, Fish and Wildlife

Service: 1-29.

Gabrielson, I.N.; Jewett, S.G. 1940. Birds of Oregon. Corvallis, OR: Oregon State College. 650 p.
68

Gabrielson, I.N.; Lincoln, F.C. 1959. Birds of Alaska. Harrisburg, PA: Stackpole Co.; Washington,

DC: Wildlife Management Institute. 922 p.

Gould, P.J.; Zabloudil, A.E. 1981. Reproductive ecology of seabirds at Middleton Island, Alaska,

14-26 June 1981. Unpublished report. 15 p. On file with: U.S. Geological Survey, Alaska Biological

Sciences Center, 1011 East Tudor Road, Anchorage, AK 99503.

Grand, J.B. 1997. Personal communication. Unit leader, U.S. Geological Survey, Alabama Cooperative Research Unit, 108 White Smith Hall, Auburn University, Auburn, AL 36849.

Grand, J.B. 1999. Personal communication. Unit leader, U.S. Geological Survey, Alabama Cooperative Research Unit, 108 White Smith Hall, Auburn University, Auburn, AL 36849.

Grand, J.B.; Anthony, R.M. 1997. Re-nesting, nest depredation, and survival of dusky Canada geese

on the Copper River Delta, Alaska. Unpublished report. 11 p. On file with: U.S. Geological Survey,

Alaska Biological Sciences Center, 1011 East Tudor Road, Anchorage, AK 99503.

Grand, J.B.; Anthony, R.M.; Fondell, T.F. 1998. Renesting, nest depredation, and gosling survival

of dusky Canada geese on the Copper River Delta, Alaska. Unpublished report. 15 p. On file with:

U.S. Geological Survey, Alaska Biological Sciences Center, 1011 East Tudor Road, Anchorage, AK

99503.

Grinnell, J. 1910. Birds of the 1908 Alexander Alaska expedition. University of California Publications in Zoology. 5: 361-428.

Gullion, G.W. 1951. Birds of the southern Willamette Valley, Oregon. Condor. 53: 129-149.

Gutierrez, R.J.; Harrison, S. 1996. Applying metapopulation theory to spotted owl management: a

history and critique. In: McCullough, D.R., ed. Metapopulations and wildlife conservation. Covelo,

CA: Island Press: 167-186.

Hansen, H.A. 1960. Annual waterfowl report, Alaska. Unpublished report. On file with: USDI Fish

and Wildlife Service, 3000 Vintage Boulevard, Suite 200, Juneau, AK 99801.

Hansen, H.A. 1961. Loss of waterfowl production to tide floods. Journal of Wildlife Management.

25(3): 242-248.

Hansen, H.A. 1962. Canada geese of coastal Alaska. Transactions of the North American Wildlife

Conference. 27: 301-329.

Hansen, H.A. 1968. Pacific Flyway Canada goose management—federal and state cooperation. In:

Hine, R.L.; Schoenfeld, C., eds. Canada goose management: current continental problems and

programs. Madison, WI: Dembar Educational Resources Service: 47-49.

Hansen, H.A.; Nelson, H.K. 1964. Honkers large and small. In: Linduska, J.P., ed. Waterfowl

tomorrow. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service: 109-124.

Hansen, W.R.; Eckel, E.B. 1971. Setting and effects of the earthquake. In: The great Alaska earthquake of 1964: geology. Washington, DC: National Academy of Sciences: 5-43.

Havel, L.H.; Jarvis, R.L. 1988. Formation of feeding flocks during winter by dusky and Taverner’s

Canada geese in Oregon. In: Weller, M.W., ed. Waterfowl in winter. Minneapolis, MN: University

of Minnesota Press: 91-101.

Hawkings, J.S. 1982. Migration and habitat relationships of geese on the eastern Copper River Delta,

Alaska. Fairbanks, AK: University of Alaska. 113 p. M.S. thesis.
69

Hearne, M. 1999. Personal communication. Observer at Delkatla Wildlife Sanctuary, Queen Charlotte

Islands, BC. P.O. Box 246, Masset, BC, Canada V0T 1M0.

Henny, C.J. 1967. Estimating band-reporting rates from banding and crippling loss data. Journal of

Wildlife Management. 31(3): 533-538.

Isleib, M.E. 1977. The Canada goose (Branta canadensis) in Prince William Sound, Alaska: a

summary. Unpublished report. 18 p. On file with: Alaska Department of Fish and Game, 525 West

67th Avenue, Anchorage, AK 99518.

Isleib, M.E. 1986. Middleton Island bird survey, 5-12 November, 1986. Unpublished report. 13 p. On

file with: University of Alaska Museum, 907 Yukon Drive, Fairbanks, AK 99775.

Isleib, M.E. 1986. Personal communication. Recognized Alaska bird expert (deceased). Cordova, AK.

Isleib, M.E.; Kessel, B. 1973. Birds of the North Gulf Coast—Prince William Sound region, Alaska.

Biological Papers 14. Fairbanks, AK: University of Alaska. 149 p.

Jarvis, R.L. 1978. The dusky Canada goose—an entrenched minority. Unpublished report. 15 p. On

file with: Department of Fisheries and Wildlife, Nash Hall, Oregon State University, Corvallis, OR

97331.

Jarvis, R.L. 1980. Status of dusky and Taverner’s Canada geese in the Willamette Valley.

Unpublished report. 10 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon

State University, Corvallis, OR 97331.

Jarvis, R.L. 1982. Status of Canada geese wintering in western Oregon-southwestern Washington.

Unpublished report. 9 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon

State University, Corvallis, OR 97331.

Jarvis, R.L. 1989. Estimated mid-winter population of dusky Canada geese, 1988-89. Unpublished

report. 4 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon State University,

Corvallis, OR 97331.

Jarvis, R.L. 1990. Estimated winter population of dusky Canada geese, 1989-90. Unpublished report.

5 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon State University,

Corvallis, OR 97331.

Jarvis, R.L. 1992. Estimated mid-winter population of dusky Canada geese—1992. Unpublished

report. 5 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon State University,

Corvallis, OR 97331.

Jarvis, R.L. 1993. Estimated mid-winter population of dusky Canada geese—1993. Unpublished

report. 4 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon State University,

Corvallis, OR 97331.

Jarvis, R.L. 1994. Estimated mid-winter population of dusky Canada geese—1994. Unpublished

report. 6 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon State University,

Corvallis, OR 97331.

Jarvis, R.L. 1995. Estimated mid-winter population of dusky Canada geese—1995. Unpublished

report. 6 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon State University,

Corvallis, OR 97331.
70

Jarvis, R.L. 1997. Estimated mid-winter population of dusky Canada geese—1997. Unpublished

report. 6 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon State University,

Corvallis, OR 97331.

Jarvis, R.L.; Bromley, R.G. 1998. Managing racially mixed flocks of Canada geese. In: Rusch,

D.H.; Samuel, M.D.; Humburg, D.D.; Sullivan, B.D., eds. Biology and management of Canada

geese: Proceedings of the International Canada Goose Symposium. Middleton, WI: Marler

Graphics: 413-423.

Jarvis, R.L.; Cornely, J. 1983. Status of Canada geese wintering in western Oregon-southwestern

Washington. Unpublished report. 10 p. On file with: Department of Fisheries and Wildlife, Nash

Hall, Oregon State University, Corvallis, OR 97331.

Jarvis, R.L.; Cornely, J. 1988. Recent changes in wintering populations of Canada geese in western

Oregon and southwestern Washington. In: Weller, M.W., ed. Waterfowl in winter. Minneapolis,

MN: University of Minnesota Press: 517-528.

Jarvis, R.L.; Rodgers, R.S. 1976. The dusky Canada goose—a new minority? Unpublished report.

18 p. On file with: Department of Fisheries and Wildlife, Nash Hall, Oregon State University,

Corvallis, OR 97331.

Jarvis, R.L.; Sekora, P. 1981. Status of Canada geese wintering in western Oregon-southwestern

Washington. Unpublished report. 8 p. On file with: Department of Fisheries and Wildlife, Nash

Hall, Oregon State University, Corvallis, OR 97331.

Jewett, S.G. 1932. The white-cheeked geese in Oregon. Condor. 34: 136.

Jewett, S.G. 1953. Branta canadensis occidentalis in the Willamette Valley, Oregon. Murrelet.

34(1): 10.

Jewett, S.G.; Taylor, W.P.; Shaw, W.T.; Aldrich, J.W. 1953. Birds of Washington state. Seattle,

WA: University of Washington Press. 767 p.

Johnson, D.H.; Timm, D.E.; Springer, P.F. 1979. Morphological characteristics of Canada geese in

the Pacific Flyway. In: Jarvis, R.L.; Bartonek, J.C., eds. Management and biology of Pacific Flyway

geese. Corvallis, OR: Oregon State University Book Stores, Inc.: 56-80.

Johnson, O.B. 1880. List of the birds of the Willamette Valley, Oregon. American Naturalist.

14: 485-491, 635-641.

Kebbe, C. 1958. Preliminary report on the western Canada goose. Unpublished report. 4 p. On file

with: USDI Fish and Wildlife Service, 911 NE 11th Avenue, Portland, OR 97232.

Kempka, R.G.; Maurizi, B.S.; Logan, D.W. [et al.]. 1995. Utilizing SPOT multispectral imagery to

assess wetland vegetation succession in the Copper River Delta, Alaska. In: Proceedings 8th North

American Arctic Goose Conference; 1995 January; Albuquerque, NM: 49. On file with: Alaska

Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Kimerling, A.J.; Jackson, P.L., eds. 1985. Atlas of the Pacific Northwest. Corvallis, OR: Oregon

State University. 136 p.

Klein, D.R. 1955. Copper River Delta banding and reproduction studies. Unpublished report. 4 p. On

file with: USDI Fish and Wildlife Service, 3000 Vintage Boulevard, Suite 200, Juneau, AK 99801.
71

Kraege, D. 1995 (15 March). Memorandum to L. Harb, biologist, USDI Fish and Wildlife Service,

Portland, OR. 2 p. On file with: Washington Department of Fish and Wildlife, 600 Capitol Way,

Olympia, WA 98504.

Kruger, L.E.; Tyler, C.B. 1995. Management needs assessment for the Copper River Delta, Alaska.

Gen. Tech. Rep. PNW-GTR-356. Portland, OR: U.S. Department of Agriculture, Forest Service,

Pacific Northwest Research Station. 45 p.

Kurhajec, D.J. 1977. Breeding Canada geese of the Port Etches area Hinchinbrook Island, Alaska.

Unpublished report. 12 p. On file with: USDI Fish and Wildlife Service, 1011 East Tudor Road,

Anchorage, AK 99503.

Lebeda, C.S. 1980. Nesting and brood rearing ecology of the Vancouver Canada goose on Admiralty

Island in southeast Alaska. Brookings, SD: South Dakota State University. 72 p. M.S. thesis.

Lebeda, C.S.; Ratti, J.T. 1984. Reproductive biology of Vancouver Canada geese on Admiralty

Island, Alaska. Journal of Wildlife Management. 47(2): 297-306.

Le Cren, E.D. 1965. A note on the history of mark-recapture population estimates. Journal of Animal

Ecology. 34: 453-454.

Levins, R. 1968. Evolution in changing environments: some theoretical explorations. Monograph in

Population Biology. Princeton, NJ: Princeton University Press.

Lowe, R. 1987. Coastal Canada geese: a preliminary report. Oregon Birds. 13(2): 143-146.

Lowe, R. 1999. Personal communication. Refuge manager, USDI Fish and Wildlife Service, Oregon

Coastal Wildlife Refuge Complex, 2127 SE OSU Drive, Newport, OR 97365.

MacCracken, J.D. 1992. Ecology of moose on the Copper River Delta, Alaska. Moscow, ID:

University of Idaho. 320 p. Ph.D. dissertation.

Macgregor, W. 1993. Collared dusky Canada geese. Victoria Naturalist. 49(4): 5.

Mayfield, H.F. 1975. Suggestions for calculating nest success. Wilson Bulletin. 87(4): 456-466.

McCullough, D.R. 1996. Metapopulation management: What patch are we in and which corridor

should we take? In: McCullough, D.R., ed. Metapopulations and wildlife conservation. Covelo, CA:

Island Press: 405-410.

McKnight, D.E. 1971. Report of survey and inventory activities—waterfowl and small game. Fed.

Aid Wildl. Rest. Prog. Report. Proj. W-17-3, Jobs 10 and 11. Juneau, AK: Alaska Department of

Fish and Game. 76 p. Vol. II.

Mech, L.D. 1970. The wolf: ecology and behavior of an endangered species. New York: The Natural

History Press. 384 p.

Meyers, P.; Cooper, E.; Fode, J. [et al.]. 2000. Artificial nest island program for dusky Canada geese

on the Copper River Delta, Alaska. Unpublished report. 10 p. On file with: USDA Forest Service,

Cordova Ranger District, P.O. Box 280, Cordova, AK 99574.

Mickelson, P.G. 1984. Brown bear, coyote, and avian predation on the dusky Canada geese of the

Copper River Delta, Alaska. Unpublished report. 32 p. University of Alaska, Fairbanks. On file

with: Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.
72

Mickelson, P.G; Hawkings, J.S.; Herter, D.R.; Murphy, S.M. 1980. Habitat use by birds and other

wildlife on the Eastern Copper River Delta, Alaska. Unpublished report. 189 p. On file with: Alaska

Cooperative Wildlife Research Unit, University of Alaska, Fairbanks, AK 99701.

Miller, S.D. 1990. Population management of bears in North America. International Conference on

Bear Research and Management. 8: 357-373.

Miller, S.D. 1997. Impacts of heavy hunting pressure on the density and demographics of brown bear

populations in southcentral Alaska. Fed. Aid Wildl. Rest. Research Final Rep. Study 4.26, Grants

W-24-2, W-24-3, W-24-4. Juneau, AK: Alaska Department of Fish and Game. 97 p.

Moffitt, J. 1937. The white-cheeked goose in California. Condor. 39: 149-159.

Morgan, R.P.; Sulkin, S.T.; Henny, C.J. 1977. Serum proteins of Canada goose (Branta canadensis)

subspecies. Condor. 79: 275-278.

Morgan, S., ed. 1989. Brown/grizzly bear, Part V. Fed. Aid Wildl. Restor. Prog. Rep. Proj W-23-1,

Study 4.0. Juneau, AK: Alaska Department of Fish and Game. 189 p. Vol. XIX.

Murphie, B.L. 1993. Distribution and abundance of migrating and wintering Canada geese at Willapa

Bay, Washington, from October 1992 through April 1993. Unpublished report. 9 p. On file with:

USDI Fish and Wildlife Service, Willapa Bay National Wildlife Refuge Complex, 3888 SR 101,

Ilwaco, WA 98624.

Naughton, M. 1992. Unpublished data and map of winter distribution of dusky Canada geese based

on sightings of CRD geese with unique neck collar codes, 1985-1991. On file with: USDI Fish and

Wildlife Service, Willamette Valley National Wildlife Refuge Complex, 26208 Finley Refuge

Road, Corvallis, OR 97333.

Naughton, M. 1993. Relations between the distribution of Canada geese and the quantity and quality

of forage at W.L. Finley National Wildlife Refuge, 1984–1987. Corvallis, OR: Oregon State

University. 85 p. M.S. thesis.

Nelson, U.C. 1953. Alaska Pacific Flyway Report. In: Pacific Flyway waterfowl report, No. 23.

Juneau, AK: U.S. Department of the Interior, Fish and Wildlife Service: A-13.

Nowlin, R. 1995. Unit 6 Prince William Sound and North Gulf Coast. In: Hicks, M.V., ed. Management report of survey—inventory activities: brown bear. Fed. Aid Wildl. Rest. Grants W-24-1 and

W-24-2. Juneau, AK: Alaska Department of Fish and Game: 35-57.

Nysewander, D.; Knudtson, P. 1977. The population ecology and migration of seabirds, shorebirds,

and waterfowl associated with Constantine Harbor, Hinchinbrook Island, Prince William Sound,

1976. In: Bartonek, J.C; Lensink, C.J.; Gould, R.G. [et al.], co-principal investigators. Population

dynamics and trophic relationships of marine birds in the Gulf of Alaska and southern Bering Sea.

Anchorage, AK: U.S. Department of the Interior, Fish and Wildlife Service: 500-575.

Ogilvie, M.A. 1978. Wild geese. Vermillion, SD: Buteo Books. 350 p.

Olson, S.T. 1953. Copper River Delta banding operations. Fed. Aid Wildl. Rest. Proj. 3-R-8, Alaska.

Juneau, AK: U.S. Bureau of Sport Fisheries and Wildlife: 34-42. On file with: USDI Fish and

Wildlife Service, 3000 Vintage Boulevard, Suite 200, Juneau, AK 99801.

Olson, S.T. 1954a. Breeding ground survey for 1954—Copper River Delta. Unpublished report. 9 p.

On file with: USDI Fish and Wildlife Service, 3000 Vintage Boulevard, Suite 200, Juneau, AK

99801.
73

Olson, S.T. 1954b. Copper River Delta banding operations. Unpublished report. On file with: USDI

Fish and Wildlife Service, 3000 Vintage Boulevard, Suite 200, Juneau, AK 99801.

Olson, S.T. 1954c. Report on Copper River banding and production studies for 1954. Migratory

waterfowl studies: banding and production studies. Fed. Aid Wildl. Rest. Proj. 3-R-8, Work Plan C.

Juneau, AK: U.S. Bureau Sport Fisheries and Wildlife. 14 p. On file with: USDI Fish and Wildlife

Service, 3000 Vintage Boulevard, Suite 200, Juneau, AK 99801.

Oregon Department of Fish and Wildlife. [N.d.]. Sauvie Island Wildlife Area—a wildlife treasure

[Brochure]. Portland, OR.

Oregon Department of Fish and Wildlife; Washington Department of Fish and Wildlife. [N.d.].

Pacific Northwest goose management: pamphlet for Canada goose hunters. Portland, OR.

Pacific Flyway Council. 1973. Guidelines for management of the dusky Canada goose. 12 p. On file

with: USDI Fish and Wildlife Service, 911 NE 11th Avenue, Portland, OR 97232.

Pacific Flyway Council. 1985. Pacific Flyway management plan for the dusky Canada goose. 23 p.

On file with: USDI Fish and Wildlife Service, 911 NE 11th Avenue, Portland, OR 97232.

Pacific Flyway Council. 1992. Pacific Flyway management plan for the dusky Canada goose. 25 p.

On file with: USDI Fish and Wildlife Service, 911 NE 11th Avenue, Portland, OR 97232.

Pacific Flyway Council. 1997. Pacific Flyway management plan for the dusky Canada goose. 46 p.

On file with: USDI Fish and Wildlife Service, 911 NE 11th Avenue, Portland, OR 97232.

Pacific Flyway Council. 1998. Pacific Flyway management plan for northwest Oregon-southwest

Washington Canada goose agricultural depredation control. Unpublished report. 33 p. On file with:

USDI Fish and Wildlife Service, 911 NE 11th Avenue, Portland, OR 97232.

Palmer, R.S., ed. 1976. Handbook of North American birds: waterfowl Part 1. New Haven, CT: Yale

University Press. 520 p. Vol. 2.

Patten, S.M., Jr. 1980. Interbreeding and evolution in the Larus glaucescens x Larus argentatus

complex on the south coast of Alaska. Baltimore, MD: Johns Hopkins University. 219 p. Ph.D.

dissertation.

Patten, S.M., Jr.; Patten, L. 1979. Evolution, pathobiology and breeding ecology of large gulls

(Larus) in the northeast Gulf of Alaska and effects of exposure of gulls and kittiwakes to petroleum.

Boulder, CO: Research Unit 99, U.S. Department of Commerce, NOAA Environmental Research

Laboratory. 315 p.

Pearce, J. 1999. Personal communication. Wildlife biologist, U.S. Geological Survey, Alaska

Biological Science Center, 1011 East Tudor Road, Anchorage, AK.

Pearce, J.B.; Bollinger, K.S. 1997. Analyses of morphological characteristics of Canada goose

subspecies parvipes and occidentalis. Unpublished report. 7 p. On file with: U.S. Geological

Survey, Alaska Biological Sciences Center, 1011 East Tudor Road, Anchorage, AK 99503.

Pearce, J.B.; Pierson, B.J.; Talbot, S.L. [et al.]. 1998. Population genetic analysis of Pacific Flyway

Canada geese and analysis of hunter check station geese. Unpublished report. 14 p. On file with:

U.S. Geological Survey, Alaska Biological Sciences Center, 1011 East Tudor Road, Anchorage,

AK 99503.

Pearce, J.B.; Pierson, B.J.; Talbot, S.L. [et al.]. 2000. A genetic evaluation of morphology used to

identify harvested Canada geese. Journal of Wildlife Management. 64: 863-874.
74

Petersen, M.P.; Greilich, J.C.; Harrison, N.M. 1981. Spring and fall migration, and habitat use

by water birds in the Yakutat forelands, Alaska—1980. Unpublished report. 106 p. On file with:

U.S. Geological Survey, Alaska Biological Sciences Center, 1011 East Tudor Road, Anchorage,

AK 99503.

Petrula, M. 2000. Dusky Canada goose survey on Middleton Island—2000. Unpublished report. 2 p.

On file with: Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Petrula, M. 2001. Dusky Canada goose production survey—2001. Unpublished report. 8 p. On file

with: Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Petrula, M. 2002. Dusky Canada goose production survey—2002. Unpublished report. 6 p. On file

with: Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Petrula, M.; Rothe, T.C.; Rosenberg, D.H.; Bethune, S. 2002. Canada goose survey on Middleton

Island—2002. Unpublished report. 5 p. On file with: Alaska Department of Fish and Game, 525

West 67th Avenue, Anchorage, AK 99518.

Pewe, T.L. 1975. Quaternary geology of Alaska. Prof. Pap. 835. Washington, DC: U.S. Geological

Survey. 145 p.

Plafker, G. 1990. Regional vertical tectonic displacement of shorelines in south-central Alaska during

and between great earthquakes. Northwest Science. 64(5): 250-258.

Plafker, T.L.; Lajoie, K.R.; Rubin, M. 1992. Determining the recurrence intervals of great subduction zone earthquakes in southern Alaska by radiocarbon dating. In: Taylor, R.E.; Long, A.; Kra, R.,

eds. Radiocarbon after four decades. New York: Springer-Verlag: 436-453.

Ploeger, P.L. 1968. Geographical differentiation in arctic Anatidae as a result of isolation during the

last glacial. Ardea. (56): 1-159.

Potyondy, J.P.; Meyer, M.P.; Mase, A.C., Jr. 1975. Hydrologic response of the Copper River DeltaController Bay Area, Alaska, to land emergence and uplift. St. Paul, MN: University of Minnesota.

81 p.

Pulliam, H.R. 1988. Sources, sinks, and population regulation. American Naturalist. 132 (5): 652-661.

Ratti, J.T.; Robards, F.C. 1977. Weights and measurements of Vancouver Canada geese. BirdBanding. 48(4): 354-357.

Ratti, J.T.; Timm, D.E. 1979. Migratory behavior of Vancouver Canada geese: recovery rate bias. In:

Jarvis, R.L.; Bartonek, J.C., eds. Management and biology of Pacific Flyway geese. Corvallis, OR:

Oregon State University Book Stores: 208-212.

Ratti, J.T.; Timm, D.E.; Anderson, D.R. 1978. Reevaluation of survival estimates for Vancouver

Canada geese: application of modern methods. Wildlife Society Bulletin. 6(3): 146-148.

Rausch, R. 1958. The occurrence and distribution of birds on Middleton Island, Alaska. Condor.

60: 227-242.

Raveling, D.G. 1978. The timing of egg laying by northern geese. Auk. 95(2): 294-303.

Rearden, J.D. 1951. Identification of waterfowl nest predators. Journal of Wildlife Management.

15: 386-395.

Reimnitz, E. 1972. Effects in the Copper River Delta. In: The great Alaska earthquake of 1964:

oceanography and coastal engineering. Washington, DC: National Academy of Sciences: 290-302.
75

Reimnitz, E.; Marshall, N.F. 1971. Effects of the earthquake and tsunami on recent deltaic sediments: tectonics. In: The great Alaska earthquake of 1964: geology. Washington, DC: National

Academy of Sciences: 265-278.

Riewe, M.E.; Mondart, C.L., Jr. 1985. The ryegrasses. In: Heath, M.E.; Barnes, R.F.; Metcalfe, D.S.,

eds. Forages: the science of grassland agriculture. 4th ed. Ames, IA: Iowa State University Press:

241-246.

Rodgers, R.S. 1973 (29 January). Letter to D.E. Timm, Waterfowl Coordinator, Alaska Department

of Fish and Game, regarding mid-winter waterfowl count on William L. Finley National Wildlife

Refuge. 5 p. On file with: Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage,

AK 99518.

Rodgers, R.S. 1974 (18 January). Letter to Regional Director, U.S. Fish and Wildlife Service,

Portland, Oregon, regarding mid-winter waterfowl count on William L. Finley National Wildlife

Refuge. 2 p. On file with: USDI Fish and Wildlife Service, Willamette Valley National Wildlife

Refuge Complex, 26208 Finley Refuge Road, Corvallis, OR 97333.

Rodgers, R.S. 1975 (28 April). Letter to D.E. Timm, Waterfowl Coordinator, Alaska Department of

Fish and Game. 1 p. On file with: Alaska Department of Fish and Game, 525 West 67th Avenue,

Anchorage, AK 99518.

Rosenberg, D.H.; Crowley, D.; Petrula, M.; Rothe, T.C. 1996. Middleton Island Canada geese: a

status report. Unpublished report. 8 p. On file with: Alaska Department of Fish and Game, 525 West

67th Avenue, Anchorage, AK 99518.

Rothe, T.C. 1993. 1993 dusky Canada goose production survey. Unpublished report. 1 p. On file with:

Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Rothe, T.C. 1994. 1994 dusky Canada goose production survey. Unpublished report. 1 p. On file with:

Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Rothe, T.C. 1995. 1995 dusky Canada goose production survey. Unpublished report. 1 p. On file with:

Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Rothe, T.C. 1996. 1996 dusky Canada goose production survey. Unpublished report. 1 p. On file with:

Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Rothe, T.C. 1997. 1997 dusky Canada goose production survey. Unpublished report. 1 p. On file with:

Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Rothe, T.C. 1998. 1998 dusky Canada goose production survey. Unpublished report. 1 p. On file with:

Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Rothe, T.C. 1999. 1999 dusky Canada goose production survey. Unpublished report. 1 p. On file with:

Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Rothe, T.C.; Petrula, M.J. 2000. Dusky Canada goose production surveys—2000. Unpublished

report. 3 p. On file with: Alaska Department of Fish and Game, 525 West 67th Avenue, Anchorage,

AK 99518.

Sargeant, A.B.; Allen, S.H.; Eberhardt, R.T. 1984. Red fox predation on breeding ducks in

midcontinent North America. Wildlife Monographs. 89: 1-41.
76

Sargeant, A.B.; Sovada, M.A.; Greenwood, R.J. 1998. Interpreting evidence of depredation of duck

nests in the prairie pothole region. Jamestown, ND: U.S. Geological Survey, Northern Prairie Wildlife Research Center; Memphis, TN: Ducks Unlimited, Inc. 72 p.

Schempf, P.F. 1999. Personal communication. Wildlife biologist, USDI, Fish and Wildlife Service,

3000 Vintage Boulevard, Suite 240, Juneau, AK 99801.

Scribner, K.; Pearce, J.; Pierson, B. [et al.]. 1997. Preliminary analyses of spatial population genetic

structuring of Canada geese from the Pacific Flyway with particular emphasis on dusky Canada

geese. Unpublished report. 11 p. On file with: U.S. Geological Survey, Alaska Biological Sciences

Center, 1011 East Tudor Road, Anchorage, AK 99503.

Scribner, K.; Talbot, S.L.; Pearce, J.M. [et al.]. [In press]. Phylogeography of Canada geese

(Branta canadensis) in western North America. The Auk. 120.

Searby, H.W. 1969. Coastal weather and marine data summary for Gulf of Alaska, Cape Spencer

westward to Kodiak Island. ESSA Technical Memorandum EDSTM 8. Silver Springs, MD: U.S.

Department of Commerce.

Seber, G.A.F. 1972. Estimating survival rates from bird-band returns. Journal of Wildlife Management. 36(2): 405-413.

Seber, G.A.F. 1973. Estimation of animal abundance and related parameters. London: Charles Griffin.

506 p.

Sellers, D. 1980 (5 June). Letter to R.G. Bromley, Oregon State University. 3 p. On file with: Alaska

Department of Fish and Game, 525 West 67th Avenue, Anchorage, AK 99518.

Sheaffer, S.E. 1993. Population ecology of the dusky Canada goose. Corvallis, OR: Oregon State

University. Ph.D. dissertation.

Sheaffer, S.E.; Jarvis, R.L. 1995. Bias in Canada goose population size estimates from sighting data.

Journal of Wildlife Management. 59(3): 464-473.

Shepherd, P.E.K. 1961. Mortality studies of western Canada geese—Copper River Delta. Annual

report of progress. Alaska Wildlife Investigations. Fed. Aid to Wildl. Rest. Rep. Proj. W-6-R-2, Job

3-A. Juneau, AK: Alaska Department of Fish and Game. 77 p. Vol. II.

Shepherd, P.E.K. 1965. Waterfowl report. Fed. Aid Wildl. Rest. Prog. Report. Proj. W-6-R-5, Work

Plan H, Jobs 1, 2 and 3. Juneau, AK: Alaska Department of Fish and Game. 16 p. Vol. VII.

Shepherd, P.E.K. 1966. Waterfowl report. Fed. Aid Wildl. Rest. Prog. Report. Proj. W-6-R-6

Work Plan H and W-13-R-1, Work Plan C. Juneau, AK: Alaska Department of Fish and Game.

26 p. Vol. VII.

Shepherd, P.E.K. 1967 (2 March). Letter to J.A. Chapman, graduate student at Oregon State

University, concerning dusky goose production and surveys during 1964-1966. 1 p. On file with:

Alaska Department of Fish and Game, 1255 West 8th Street, Juneau, AK 99802.

Shepherd, P.E.K.; Hilliker, B.L.; Crow, J.H. 1968. Waterfowl report. Fed. Aid Wildl. Rest. Prog.

Report. Proj. W-13-R-2 and 3, Work Plan C. Juneau, AK: Alaska Department of Fish and Game.

39 p. Vol. IX.

Shepherd, P.E.K.; Hilliker, B.L.; Somerville, R.J. 1967. Waterfowl report. Fed. Aid Wildl. Rest.

Prog. Report. Proj. W-13-R-1 and 2, Work Plan C. Juneau, AK: Alaska Department of Fish and

Game. 27 p. Vol. IX.
77

Shields, G.F.; Connor, J.P. 1998. Phylogenies of North American geese: the mitochondrial DNA

record. In: Rusch, D.H.; Samuel, M.D.; Humburg, D.D.; Sullivan, B.D., eds. Biology and

management of Canada geese: Proceedings of the International Canada Goose Symposium.

Middleton, WI: Marler Graphics: 405-411.

Shields, G.F.; Wilson, A.C. 1987a. Calibration of mitochondrial DNA evolution in geese. Journal of

Molecular Evolution. 24: 212-217.

Shields, G.F.; Wilson, A.C. 1987b. Sub-species of the Canada goose (Branta canadensis) have

distinct types of mitochondrial DNA. Evolution. 41: 662-666.

Sibley, C.G.; Monroe, B.L. 1990. Distribution and taxonomy of birds of the world. New Haven, CT:

Yale University Press.

Simpson, S.G.; Jarvis, R.L. 1979. Comparative ecology of several subspecies of Canada geese during

winter in western Oregon. In: Jarvis, R.L.; Bartonek, J.C., eds. Management and biology of Pacific

Flyway geese. Corvallis, OR: Oregon State University Book Stores: 223-241.

Smith, J.L. 1971. Subspecies composition of wintering Canada geese in the mid-Willamette Valley of

Oregon. Unpublished report. 22 p. On file with: USDI Fish and Wildlife Service, William L. Finley

National Wildlife Refuge, 26208 Finley Refuge Road, Corvallis, OR 97333.

Sooter, C.A. 1946. Habits of coyotes in destroying nests and eggs of waterfowl. Journal of Wildlife

Management. 10: 33-38.

Stehn, R. 1991. Nesting populations and production of geese on the Yukon-Kuskokwim Delta.

Unpublished report. 99 p. On file with: U.S. Geological Survey, Alaska Biological Sciences Center,

1011 East Tudor Road, Anchorage, AK 99503.

Stehn, R. 1992. Analysis of dusky Canada goose aerial survey data on breeding pairs and production,

1978-1991. Unpublished report. 5 p. On file with: U.S. Geological Survey, Alaska Biological

Sciences Center, 1011 East Tudor Road, Anchorage, AK 99503.

Stehn, R. 1999. Personal communication. Wildlife biologist, USDI, Fish and Wildlife Service,

Migratory Bird Management, 1011 East Tudor Road, Anchorage, AK 99503.

Stephenson, T.R.; Van Ballenberghe, V. 1995. Wolf, Canis lupus, predation on dusky Canada geese,

Branta canadensis occidentalis. Canadian Field-Naturalist. 109: 253-255.

Stephenson, T.R.; Van Ballenberghe, V.; Peek, J.M. 1993. Ecology of wolves on the north Gulf

Coast of Alaska. Unpublished report. 32 p. On file with: USDA Forest Service, Pacific Northwest

Research Station, 3301 C Street, Suite 200, Anchorage, AK 99503.

Swarth, H.S. 1911. Birds and mammals of the 1909 Alexander Alaska expedition. University of

California Publications in Zoology. 7: 9-172.

Taylor, M.K.; Bunnell, F.; Schweinsburg, R. 1987. Modeling the sustainable harvest of female polar

bears. Journal of Wildlife Management. 51(4): 811-820.

Thilenius, J.F. 1990a. Plant succession on earthquake uplifted coastal wetlands, Copper River Delta,

Alaska. Northwest Science 64(5): 259-262.

Thilenius, J.F. 1990b. Woody plant succession on earthquake-uplifted coastal wetlands of the Copper

River Delta, Alaska. Forest Ecology and Management. 33/34: 439-462.
78

Thilenius, J.F. 1995. Phytosociology and succession on earthquake-uplifted coastal wetlands, Copper

River Delta, Alaska. Gen. Tech. Rep. PNW-GTR-346. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 58 p.

Timm, D.E. 1972a. Personal communication. Waterfowl coordinator (retired), Alaska Department of

Fish and Game, Anchorage, AK.

Timm, D.E. 1972b. Report of survey and inventory activities—waterfowl. Fed. Aid Wildl. Rest. Prog.

Report. Proj. W-17-4, Job 10. Juneau, AK: Alaska Department of Fish and Game. 46 p. Vol. IV.

Timm, D.E. 1974. Report of survey and inventory activities—waterfowl. Fed. Aid Wildl. Rest. Prog.

Report. Proj. W-17-6, Job Nos. 11 and 22. Juneau, AK: Alaska Department of Fish and Game. 53 p.

Vol. V.

Timm, D.E. 1975. Report of survey and inventory activities—waterfowl. Fed. Aid Wildl. Rest. Prog.

Report. Proj. W-17-7, Jobs 11 and 22. Juneau, AK: Alaska Department of Fish and Game. 53 p.

Vol. VI.

Timm, D.E. 1976. Report of survey and inventory activities—waterfowl. Fed. Aid Wildl. Rest. Prog.

Report. Proj. W-17-8, Job 11. Juneau, AK: Alaska Department of Fish and Game. 61 p. Vol. VII.

Timm, D.E. 1977. Report of survey and inventory activities—waterfowl. Fed. Aid Wildl. Rest. Prog.

Report. Proj. W-17-9, Jobs 11 and 22. Juneau, AK: Alaska Department of Fish and Game. 37 p.

Vol. VIII.

Timm, D.E. 1978. Report of survey and inventory activities—waterfowl. Fed. Aid Wildl. Rest. Prog.

Report. Proj. W-17-10, Job No. 10. Juneau, AK: Alaska Department of Fish and Game. 27 p.

Vol. IX.

Timm, D.E. 1980. Report of survey and inventory activities—waterfowl. Fed. Aid Wildl. Rest. Prog.

Report. Proj. W-19-1, Job No. 10. Juneau, AK: Alaska Department of Fish and Game. 35 p. Vol. IX.

Timm, D.E. 1982. Annual report of survey and inventory activities—waterfowl. Fed. Aid Wildl. Rest.

Prog. Report. Proj. W-19-2, Job No. 11. Juneau, AK: Alaska Department of Fish and Game. 48 p.

Vol. X.

Timm, D.E.; Bromley, R.G.; McKnight, D.; Rodgers, R.S. 1979. Management evolution of dusky

Canada geese. In: Jarvis, R.L.; Bartonek, J.C., eds. Management and biology of Pacific Flyway

geese. Corvallis, OR: Oregon State Univ. Book Stores: 322-330.

Timm, D.E.; Havens, P. 1973. Report of survey and inventory activities—waterfowl. Fed. Aid Wildl.

Rest. Prog. Report. Proj. W-17-5, Jobs 10 and 22. Juneau, AK: Alaska Department of Fish and

Game. 64 p. Vol. IV.

Timm, D.E.; Sellers, R. 1979. Annual report of survey and inventory activities—waterfowl. Fed. Aid

Wildl. Rest. Prog. Report. Proj. W-17-11, Jobs 10. Juneau, AK: Alaska Department of Fish and

Game. 29 p. Vol. X.

Townsend, J.K. 1839. Narrative of a journey across the Rocky Mountains to the Columbia River and

a visit to the Sandwich Islands, Chili [sic], etc. [with scientific appendix]. Philadelphia, PA: Henry

Perkins. 352 p.

Trainer, C.E. 1959. The 1959 western Canada goose (Branta canadensis occidentalis) study on the

Copper River Delta, Alaska. 11 p. On file with: USDI Fish and Wildlife Service, 3000 Vintage

Boulevard, Suite 200, Juneau, AK 99801.
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