Forest

Service

United States

Department of

Agriculture

Pacific Northwest

Research Station

PNW-GTR-542

May 2002 (Revised August 2002)

	

	

		

Ellen Weintraub Lance
Ellen Weintraub Lance was a wildlife biologist, Tongass National Forest, Thorne Bay Ranger District, P.O. Box

19001, Thorne Bay, AK 99919. She is now with the U.S. Fish and Wildlife Service, Ecological Services, 605 W. 4th

Avenue, Room G61, Anchorage, AK 99501.

Author
Abstract

Lance, Ellen Weintraub. 2002. Montague Island vole: a conservation assessment. Gen. Tech. Rep.

PNW-GTR-542. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest

Research Station. 14 p.

Montague Island tundra voles were first described in the early 1900s. Based on their large size and dark

coloration relative to other island and mainland populations, tundra voles from Montague Island were

classified as a distinct subspecies. Research conducted in the 1990s revealed significant differences in

the size and shape of Montague Island voles, but not significant genetic differentiation. Montague

Island voles appeared abundant in the 1990s, although there was no attempt to estimate population size.

Montague Island voles may be reproductively and genetically isolated. More sensitive genetic

techniques now can be used to test genetic distinctiveness across populations. A conservation concern

exists owing to the unknown population status and still questionable taxonomy of this island endemic

subspecies, because it is unknown if land management practices affect this isolated population.

Keywords: Tundra vole, island endemics, Microtus oeconomus elymocetes, Montague Island, Montague

Island vole, taxonomy.

Montague Island Vole
Contents

1 Background

1 A Brief History of the Taxonomic

Classification of Montague Island Voles

1 A Brief Description of Montague Island

2 A Brief History of Human Use of Montague

Island

3 Current Status of the Montague Island Vole

3 Review of Technical Knowledge

3 Distribution

4 Systematics

4 Age Structure and Sex Ratio

4 Reproductive Potential

4 Litter Size

5 Breeding Biology

5 Movements

5 Dispersal

5 Habitat Use

5 Food Habits

5 Habitat Availability

6 Home Ranges

6 Seasonal Differences

6 Movement Patterns

6 Relation to Spatial Scale

6 Relation to Food Sources

6 Conservation Concerns

6 Population Density

6 Mortality

7 Effects of Land Management Activities

7 Managment Issues

7 Relation to Human Activities and Management

Actions

8 Landscape Structure

8 Montague Island Vole Response to

Management Actions

8 Risk Assessment

8 Approaches to Montague Island Vole

Conservation

8 Information Needs

9 English Equivalents

10 References
1

Background

A Brief History of the Taxonomic

Classification of Montague Island

Voles

Montague Island voles were first collected from

Montague Island, Prince William Sound, Alaska,

by Osgood in 1906. He described Microtus

elymocetes as a new species based on their very

large size and dark pelage. In 1910, Heller published an account of the Montague Island vole

based on 30 specimens he collected during the

Alexander expedition of 1908. He claimed “this

species is easily distinguishable from any other

member of the genus inhabiting the region by its

larger size and much darker coloration” (Heller

1910).

Zimmermann (1942) grouped M. elymocetes with

M. oeconomus based on the overall variability in

skulls and uniformity in coloration of all tundra

voles sampled, but assigned the island form subspecific status because of its relatively large size.

Paradiso and Manville (1961) concurred with

Zimmermann’s revision of Montague Island vole

after examining seven specimens from the type

locality.

A Brief Description of Montague

Island

Montague Island has been shaped by periods of

glaciation and tectonic activity resulting from the

collision of the Pacific and North American plates

(Gehrels and Saleeby 1987, Lahr and Plafker 1980).

Deep ocean channels, created by past glacial

retreats, surround and isolate the island. It is the

largest island (850 km2

) in Prince William Sound

(fig. 1) (USDA Forest Service 1993). A long

mountain range, extending north to south, divides

the island, which ranges in elevation from sea

level to more than 1000 m at its highest peak. The

eastern coast is exposed to the Gulf of Alaska and

is characterized by steep cliffs that abut the

shoreline. One large drainage, the Nellie Martin

Figure 1—Montague Island is a large island, isolated by the deep, saltwater channels

of Prince William Sound, south-central Alaska.
2

River, flows to the east. The western coast has

many rivers and bays, which are protected from

the violent storms and southeasterly winds from

the Gulf of Alaska.

Current evidence suggests the climate of the

region has remained relatively constant during the

last 5,000 years (Heusser 1985). Anticyclone

storms circulate over the Pacific Ocean most of

the year. Cyclonic storms affect the Alaska coastline in autumn and winter producing semipermanent, low-pressure systems characterized by

strong southerly or southeasterly winds and heavy

precipitation (Mobley and others 1990).

The Prince William Sound region has generally

heavy annual precipitation and cool mean annual

temperatures. During a year of extremely high

rainfall, 840 cm of precipitation was recorded

from southeastern Montague Island, and mean

annual precipitation in the Montague Island vicinity

ranged from 236 cm at Latouche Island to 216 cm

at Hinchinbrook Island (Brower and others 1988).

In addition, mean annual maximum temperatures

ranged from 7.3 o

C at Latouche Island to 9.6 oC

at Hinchinbrook Island, and mean annual minimum

temperatures ranged from 3.1 o

C at Latouche

Island to 4.1 o

C at Hinchinbrook Island (Brower

and others 1988).

Vegetation was described following Viereck and

others (1992), and varies by altitude (Lance and

Cook 1995, Weintraub and Cook 1991). Beachrye (Elymus arenarius Linnaeus) dominates the

shorelines and Sitka spruce (Picea sitchensis

(Bongard) Carriere) and alder (Alnus spp. Mill)

on alluvial deposits; sedge-moss bog meadows,

sweetgale (Myrica gale Linnaeus) -graminoid

bogs, and willow (Salix spp. Linnaeus) -graminoid

shrub bogs are interspersed among Sitka spruce

and western hemlock (Tsuga heterophylla

(Rafinesque-Schmaltz) Sargent) forests at midelevation; and mountain hemlock (Tsuga

mertensiana (Bongard) Sargent) and mountainheath (Phyllodoce aleutica (Sprengel) Heller)

tundra dominates high-elevation community types.

(Species names are according to Hulten 1968.)

Where previous timber harvest has occurred, forest

stands regenerate naturally and currently contain

even-aged stands of western hemlock and Sitka

spruce (USDA Forest Service 1989, Weintraub

and Cook 1991).

A Brief History of Human Use of

Montague Island

Historically, Montague Island supported small

populations of humans from as early as 2000 years

BP (Yarborough 1999). Local Eskimos used the

southeastern coast of Montague Island as a hunting

ground for sea otters. The Eskimos referred to

Montague Island as Sukluk, which translates to the

terrible island (Johnson 1999), presumably because

of its violent eastern shoreline. Although a village at

Zaikof Bay persisted for some unknown length of

time (Johnson 1984), currently there are no human

inhabitants on Montague Island.

Montague Island is largely federally owned (787

km2

) (USDA Forest Service 1993); however, 63

km2 were conveyed to the Chugach Alaska Corporation, under the authority of the Alaska Native

Claims Settlement Act (ANCSA 1971). A 56-kmlong road constructed in 1993, which linked the

deep-water port at McLeod Harbor to Chugach

Alaska Corporation land at Patton Bay, was

obliterated in 1997 (USDA Forest Service 1989).

Public lands on Montague Island are managed by

the USDA Forest Service, Chugach National

Forest, Cordova Ranger District. Private lands

are managed by the Chugach Alaska Corporation,

Anchorage, Alaska.

Between 1947 and 1973, about 12 km2

 of highvolume timber was harvested along the western

coast of Montague Island (USDA Forest Service

1989). Those stands regenerated naturally and

currently contain uniform stands of western

hemlock and Sitka spruce that are densely

vegetated by salmonberry (Rubus spectabilis

Pursh) (USDA Forest Service 1989, Weintraub

and Cook 1991). In 1992, 55.5 km of road was

constructed across public land to access about

48.5 km2

 of privately owned forest near Patton

Bay. Within the 48.5 km2

, about 16 km2 containing

merchantable timber was clearcut during a 6-year

period. Additionally, 3 million board feet of timber

was harvested from the McLeod Harbor area in

1998 (Jandro 1999). Recreational cabins, maintained by the USDA Forest Service, are located
3

at Port Chalmers, San Juan Bay, and Nellie

Martin River.

Sitka black-tailed deer (Odocoileus hemionus

Rafinesque), introduced to Prince William Sound

in the early 1950s (Burris and McKnight 1973),

b/and brown bear (Ursus arctos Linnaeus) have

been hunted heavily on Montague Island. As a

result, bear populations were seriously depleted.

In 1990, the Alaska Department of Fish and

Game closed the fall bear hunting season (Alaska

Board of Game 1990) and in 1994 completely

closed Montague Island to bear hunting by

emergency order followed by an Alaska Board of

Game ruling (Alaska Board of Game 1994). Bear

hunting on Montague Island remains closed at this

writing (Crowley 1999). Additionally, mink

(Mustela vison Schreber) were introduced to

Montague Island in the early 1950s and are

present today at an unknown density (Burris and

McKnight 1973).

Current Status of the Montague

Island Vole

Population status—Currently, the Montague

Island vole is designated a Sensitive Species

(USDA Forest Service 1990) and Management

Indicator Species for the Chugach National Forest

(USDA Forest Service 1989), a population for

which there is insufficient knowledge (IK) for the

International Union for the Conservation of Nature

(IUCN) (Lance and Cook 1998a), and G5T2/S2,

a population of high ecological concern both in

Alaska and nationally (West 1991). Additionally,

the Montague Island vole was previously a U.S.

Fish and Wildlife Service, Category II Candidate

(58 FR 51144) for listing under the Endangered

Species Act of 1973, as amended (U.S. Fish and

Wildlife Service 1991).

Population concerns—Species of Microtus

tend to dominate their small mammal communities,

both behaviorally and numerically (Cameron 1964,

Pruitt 1968). They can potentially alter a plant

community through selective harvest or plant

growth stimulation through grazing (Rose and

Birney 1985). In addition, they play an important

role as prey to an array of carnivores, and in their

ability to influence predator populations (Magoun

and Johnson 1991).

Researchers have long been intrigued with annual

fluctuations and multiannual cycles in Microtus

population abundance (see Batzli 1992 for review).

More populations of species of Microtus exhibit

annual fluctuations than multiannual cycles, yet

change in population abundance owing to

multiannual cycles is more dramatic (Taitt and

Krebs 1985).

Currently, there are no data available on population

estimation for the Montague Island vole. Moreover,

the U.S. Fish and Wildlife Service recommends

further investigation of population trends before

adopting further land use practices on Montague

Island (Lance and Cook 1995).

Review of Technical

Knowledge

Distribution

The tundra vole, Microtus oeconomus (Pallas)

has a Holarctic distribution (Musser and Carleton

1993). Its Old World range extends from

Scandinavia, the Netherlands, and Hungary,

eastward and south to China and Mongolia, and

throughout Siberia (Hoffmann and Koeppl 1985).

Its New World range extends from St. Lawrence

Island in the Bering Sea, throughout Alaska, and

east to the Yukon and Northwest Territories

(Musser and Carleton 1993). Although it was

once believed that the Nearctic and Palearctic

tundra voles were distinct groups, they now are

considered conspecific based on morphologic and

biochemical similarities (Lance 1995, Nadler and

others 1978, Zimmermann 1942). Currently, there

are 10 subspecies of tundra vole recognized in the

New World (Hall 1981, Paradiso and Manville

1961).

Montague Island voles (M. o. elymocetes) are an

endemic population to Montague Island in Prince

William Sound, south-central Alaska. These voles

occur throughout the island, and have been

recorded from shoreline to alpine (Heller 1910,

Lance 1995, Lance and Cook 1995).
4

Systematics

Large size and dark color, relative to other tundra

voles, make the Montague Island vole population

unique. In general, tundra voles are stocky mouselike rodents with small ears and short tails. The

body is dull brown with a grayish belly and the tail

is bicolored (Burt and Grossenheider 1976).

Montague Island voles were reported by Osgood

(1906) as darker than other populations, with

“upperparts cinnamon to clay color.” Coat color

comparisons of tundra vole collections housed at

the University of Alaska Museum confirm this

observation (Lance and Cook 1995). Coat color

polymorphisms are well documented in species of

Microtus; however, the mechanisms for their

maintenance are poorly understood (Gaines

1985). This coat color difference may be an

example of Gloger’s Rule (Allaby 1994): animals

living in warmer, humid areas generally exhibit

darker pigmentation than those occurring in cool,

dry areas. In addition, the large body size of adult

Montague Island voles is conspicuous; total length

ranges up to 225 mm, which is 35 mm larger than

tundra voles from other populations (Lance and

Cook 1995). This trend toward large body size is

consistent with Foster’s Rule, which states that

insular rodents exhibit larger body size than their

mainland relatives (Foster 1963).

Current analyses, of size and shape variation, substantiates findings previously described (Lance

1995). After removal of variation owing to size

(age) alone, significant variation between Montague

Island voles and other tundra voles remains

(Lance 1995). These data suggest the differences

distinguishing Montague Island voles from other

tundra voles were related to both size and shape.

However, body size and shape may have a strong

nongenetic basis in rodents (Smith and Patton

1988), and chromosomal and biochemical evidence

(Lance 1995; Lance and Cook 1995, 1998b)

indicates there is no genetic differentiation between

M. o. elymocetes and other subspecies of tundra

vole.

Age Structure and Sex Ratio

Age ratio (adult to subadult), as determined by the

shape of the skull and suture closure (Choate and

Williams 1978, Lance 1995, Lance and Cook 1995)

was reportedly 65:24. Sex ratio (male to female)

was 36:53 (Lance and Cook 1995).

Reproductive Potential

Age at sexual maturity and length of the breeding

season may be highly variable in microtine rodents

(Keller 1985). Sexual maturity is determined by

weight, which is regulated by environmental

conditions (that is, weather, forage availability, and

quality) and not necessarily by age (Kaikusalo and

Tast 1984, Nadeau 1985, Tast 1984). During the

summer months of 1991 and 1992 on Montague

Island, 66 percent of adult females and no subadult

female tundra voles were reproductive (Lance

and Cook 1995). Additionally, 58 percent of adult

males were reproductive, compared with 31 percent

of subadult males.

Breeding spans from May through September, but

can be highly variable based on environmental

cues (Keller 1985, Tast and Kaikusalo 1976,

Whitney 1976). Additionally, breeding may occur

year-round if environmental conditions are good

(Kaikusalo and Tast 1984, Tast 1984). Mean

gestation period is 20.5 days (Dieterich and

Preston 1977, Morrison and others 1976).

Tundra voles potentially can breed three times

annually, twice during the warm summer months

and once in winter (Kaikusalo and Tast 1984).

This ecological strategy of high productivity is

attributable to existence in uncertain environments

(MacArthur and Wilson 1967).

Litter Size

Environmental factors cue the onset and duration

of breeding and the age of the female may affect

litter size. Reproductive data for 89 individuals,

collected June through August 1991 and 1992,

from Prince William Sound indicate that mean

number of embryos is 6.5 (s.d. 1.29, N=18; Lance

and Cook 1995). Additionally, the following data

on litter size (number of embryos) were collected

from other subspecies of tundra vole: 7.8 in late

June to 5.0 in late August (Bee and Hall 1956),

6.1 in July to 5.2 in August (Youngman 1975), 7.1

in summer to 3.5 in winter (Kaikusalo and Tast

1984), and a mean of 6.9 for all months combined

(Whitney 1977).
5

Breeding Biology

Multiannual cycles in abundance are known to

occur in tundra voles (Whitney 1976). Tundra vole

populations, studied on the Kenai Peninsula between

1968 and 1971, were reportedly cyclic, peaking at

70 to 80 animals per hectare (Whitney 1976).

Typically, there is no spring decline in population

density during years of cyclic peak densities (Taitt

and Krebs 1985). Spacing behavior, operating

through differential dispersal and territory size, may

play an important role in adjustment of densities.

These phenomena may be controlled both

phenotypically and genotypically, that is, determined

partly by genetic predisposition and partly by

behavioral adjustments (Taitt and Krebs 1985).

Movements

Tundra voles disperse from their home range when

(1) the habitat is saturated and essential resources

are limited and (2) low density areas occur. Tast

(1966) reports that tundra voles seasonally reinvade flooded areas, not suitable for habitation at

certain times of the year. Some species of Microtus

are known to “wander,” that is, leave their home

range but return thereafter, and others are nomads,

never establishing a home range (Lidicker 1985).

Dispersal

Dispersal among Microtus is positively correlated

with population density (Gaines and McClenaghan

1980) and has an impact on the population’s age

structure, natality and mortality rates, and sex

ratios (Lidicker 1985). Saturation dispersal tends

to be unbiased in the sex of the disperser. Moreover,

increases in vole population numbers could prompt

dispersal and occupation of suboptimal habitats

(Tast 1984).

Seasonal dispersal at the onset of breeding season

tends to be favored by subadult males (Lidicker

1985). Colonizing dispersal, in which animals

establish home ranges in areas of lower density,

has been reported in tundra voles (Buchalczyk

and Pucek 1978, Tast 1966), and reproductive

females seem to be most successful at this type

of dispersal (Lidicker 1985).

Habitat Use

High populations of Microtus typically are

associated with early stages of plant succession

(Rose and Birney 1985), when grasses and woody

perennials dominate the plant community (Wetzel

1958). Montague Island voles have been found

most frequently in beach fringe zones consisting

of beach rye and beach pea (Lathyrus maritimus

Linnaeus), and often are found in association with

riparian vegetation, such as skunk cabbage

(Lysichiton americanum Schott) (Weintraub and

Cook 1992). They build extensive runway systems

in moss and sand under thick, matted layers of

dead stalks of beach rye. They also have been

captured in wet muskeg and subalpine meadows.

Historically, they have been reported in every

vegetation type from shoreline to alpine, including

forest (Heller 1910).

Food Habits

The gastrointestinal tracts of Microtus appear to

be adapted for high-fiber, low-protein, and lowmineral diets (Batzli 1985). Microtine rodents are

primarily vegetarians, and the genus Microtus has

adapted to a highly fibrous and siliceous diet by

evolving rootless molars that continue to grow

through their life (Batzli 1985). In some species of

Microtus, diet during breeding season consists of

mostly fresh stems and leaves, gradually shifting

to seeds, stem bases, and roots as the aboveground parts of the plants age and die (Batzli

1985). Summer diets of tundra voles in Alaska

may consist of sedges (Carex) and cottongrass

(Eriophorum angustifolium Honckeny) (Cornely

1999). Provisioning of high-quality food can

maintain breeding during winter (Cole and Batzli

1978). Indeed persistence of reproduction, litter

size, body growth, and survival rates must depend

on nutrient content of forage (Batzi 1985).

Habitat Availability

Beach fringe habitat, as described by Weintraub

and Cook (1991, 1992), is commonly encountered

along Montague Island’s extensive coastline and

appears to be the main plant community used by

Montague Island voles. However, during peak

periods of population cycles, “surplus” animals may

be pushed into less preferred habitat (Getz 1985).
6

Home Ranges

Territory size and spacing behavior may be

dependent on sex and age, genetic predisposition,

and behavioral adjustments to local population

densities (Taitt and Krebs 1985). They are

polygynous (Heske and Ostfeld 1990, Lambin

and others 1992); males hold mutually exclusive

breeding territories containing the home ranges

of one to several females. The relation between

density and home range of tundra voles is

parabolic and is expressed as:

S = 0.11 + (3.55/d) ,

where S = the home range size in hectare and d is

the density in voles per hectare (Madison 1985).

Seasonal Differences

During the winter months, Montague Island voles

may move to higher elevations where snow conditions are more conducive to subnivean living.

However, little is known about then habitats used

by Montague Island voles during winter. Microtine

rodents use subnivean environments in winter,

when snow cover is deep. In June 1991, a vole

nest was found buried in snow in an alpine meadow

above Port Chalmers (150 m) (Weintraub and

Cook 1991). Snow conditions along the beach

vary annually (Youkey 1999) and may be unsuitable for subnivean living owing to wet conditions or

lack of snow in some winter months. Alternatively,

voles preferentially may use forests in the winter

months, where they may be more protected from

winter elements; the forest canopy intercepts snow

(Hanley and Rose 1987), and dead and down

timber or root wads may provide natural shelter.

In general, snow depth on Montague Island

increases as elevation increases, and decreases

with increased timber volume (Youkey 1992).

Movement Patterns

Male tundra voles move farther and more often

than females during the reproductive period, and

move similarly to females during winter (Madison

1985, Whitney 1976). During winter, tundra voles

are social (Kaikusalo and Tast 1984, Tast 1966).

There are no data about the seasonal movements

of Montague Island voles.

Relation to Spatial Scale

Male tundra voles may range 7300 m2, and

females 3000 m2

 in summer (Karulin and others

1976). Tundra voles can swim, but it is unknown

how far a wandering or dispersing individual will

travel (Lidicker 1985).

Relation to Food Sources

Increased body size of Montague Island voles

may be related to differences in nutrition, as

demonstrated for pocket gophers (Thomomys

bottae Huey) (Patton and Brylski 1987), or a

result of increased resource availability owing to

decreased predation or competition (Case 1978).

However, Lance (1995) found that competitive

release did not explain large body size in

Montague Island voles.

Conservation Concerns

Population Density

No data are currently available about population

vigor or density. Heller (1910) describes Montague

Island voles as abundant wherever he landed on

the island, and in all vegetation types. In 1991, 70

Montague Island voles were trapped, by using

Sherman live traps and museum special snap traps,

in 7,314 trap nights (Weintraub and Cook 1991). In

1992, 25 Montague Island voles were trapped in

304 trap nights (Weintraub and Cook 1992). Trap

success between the two years are not comparable,

however, because trap effort was distributed

among all habitat types on the island in 1991 and

concentrated in beach fringe habitat in 1992.

Mortality

Naturally occurring predators on Montague Island

include raptors, brown bears, river otters (Lontra

canadensis Schreber), mink, and dusky shrews

(Sorex monticolus Merriam). Bald eagles

(Haliaeetus leucocephalus Linnaeus) are

common on Montague Island, and great horned

owls (Bubo virginianus Gmelin) are known to be

present (Lance and Cook 1995). Other raptor

species that may be present include peregrine

falcon (Falco peregrinus Tunstall), goshawk

(Accipiter gentilis Linnaeus), sharp-shinned
7

hawk (Accipiter striatus Vieillot), short-eared

owl (Asio flammeus Pontoppidan), boreal owl

(Aegolius funereus Linnaeus), screech owl

(Otus kennicottii Elliot), and saw-whet owl

(Aegolius acadicus Gmelin). Of these species, the

boreal owl and saw-whet owl specialize in yearround capture of mice (Snyder and Wiley 1976).

Brown bears from mainland Alaska are not known

to feed on voles as a primary food source (Pearson

1985). Likewise, brown bears found on Montague

Island are not likely to rely on tundra voles as a

primary food source, because they feed heavily

on the salmon (Oncorhynchus spp. Walbaum)

that return to their natal freshwater streams.

However, predation on tundra voles may occur in

spring before the first salmon runs. This protein

source may be vital to bear survival when they

arise from winter denning.

Other species that may affect survival of Montague

Island voles include mink and river otter that are

known for killing, stockpiling, and eating tundra

voles (Pearson 1985). Moreover, because of their

small size, shrews are able to follow voles through

their runways into their nest. Although there is

little information about how effective shrews are

at preying on voles in the wild, Sorex monticolus

probably eat newborn tundra voles (Pearson 1985).

Parasites and diseases also may play an important

role in the life cycle of Montague Island voles

(Lance 1995, Lance and Cook 1995). Spleen

enlargement was noted in 93 percent (N=44) of

Montague Island voles examined (Lance and

Cook 1995). Splenic weights averaged 5.4 percent

of the total body weight of adult females and

males. Previous work noted similar symptoms in

microtines, including M. oeconomus, and identified

a protozoan blood-parasite (Babesia spp.) as the

cause of the disease (Fay and Rausch 1969,

Ristic 1988, Ristic and Kreier 1981). The usual

vector of babesias in nondomesticated animals is

the Ixodid tick (Ristic 1988), and, perhaps noncoincidentally, the occurrence of Babesia microti

in Alaska microtines parallels the geographic

distribution of Ixodes angustus (Fay and Rausch

1969). The parasitemia, known as babesiosis, is

not known to be lethal to its natural hosts, but

persists in the chronic stage for the duration of the

life of the animal (Fay and Rausch 1969).

However, it is unknown how it affects individual

host fitness. Reproductive output data suggest the

number of embryos per breeding female was

lower when splenomegaly was present; average

number of embryos produced by animals exhibiting

the splenomegaly was 5.75 (s.d. 0.975, N=4)

compared to an average of 7.25 (s.d. 0.975, N=4)

embryos produced by adult females that did not

exhibit spleen enlargement (Lance and Cook 1995).

Tundra voles are known to survive and even

breed in cold temperatures, above and below

snow cover, as long as food conditions are good

(Tast 1984). No mortality from direct human

influences is known.

Effects of Land Management

Activities

Species of Microtus that occur in forest areas

generally are restricted to grassy clearings or sites

where understory grasses or sedges proliferate;

however, island populations of Microtus have

been found in wooded habitats (Cameron 1958,

Grant 1971). Habitat reduction for microtine

rodents has resulted primarily from conversion of

grasslands for farming and grazing (Getz 1985).

Wet areas, drained and filled for farming, have

been left unavailable to some populations of

Microtus. Conversely, grassy edges along roadsides have provided extensive habitats for some

species of Microtus. Moreover, Microtus

oregoni often is found in early successional

stages of clearcut forest sites (Getz 1985).

Management Issues

Relation to Human Activities and

Management Actions

Depletion of forest habitat on Montague Island is

of concern because of the lack of knowledge

about seasonal habitat use and habitat use during

high population densities by the Montague Island

vole. Other plant communities on Montague

Island are relatively unmodified by humans.
8

Landscape Structure

There are no data to address the landscape

features that might impede a dispersing or

traveling tundra vole.

Montague Island Vole Response to

Management Actions

Because seasonal movements and dispersal

patterns have not been investigated, Montague

Island vole response to timber harvest, road

building, and hunting regulations cannot be assessed

at this time. Currently, there is little evidence to

suggest that Montague Island voles have been

adversely affected by deforestation or road construction. If, however, voles depend on closedcanopy forests for protection from winter elements

or expand into forest habitats during high population

densities, depletion of forest habitat could affect

the health of the population.

Introduction of mink to Montague Island may affect

vole populations through predation pressure. It is

unclear, however, that a sustainable population of

mink still exists on Montague Island (Crowley 1999).

Risk Assessment

Predators could have a negative impact following

a “crash” in the tundra vole population. Heavy

predation pressures on waning population densities

could result in population extirpation (Rose and

Birney 1985); however, given the current distribution and availability of good habitat for voles on

Montague Island, this seems a remote possibility.

It is unknown if the Montague Island vole population is cyclic, or what constitutes the boundaries

of a population.

Approaches to Montague Island

Vole Conservation

The taxonomic evidence regarding the subspecific

validity of Montague Island vole is equivocal, and

the potential effects that disease, predation, and

management practices may have on the population

is unknown at this time. Because beach fringe

habitats may be necessary to maintain population

viability of the tundra vole populations on Montague

Island, the habitat relation should be more clearly

understood. Moreover, the distribution of populations should be mapped so that critical habitat

can be identified.

Information Needs

Information about population trends, seasonal

habitat use, and effects of the disease, babesiosis,

on Montague Island voles and tundra voles from

adjacent islands and the mainland is lacking. Indexing is a cost-effective technique for monitoring the

health of a population through time. Small-mammal

population trends can be assessed relatively easily

through removal trapping along lines or arrays set

in specific vegetation types. In addition, data carefully collected through this type of sampling would

be useful in identifying and assessing causes and

progression of disease, such as babesiosis.

A large series of tissue and skeletal samples from

Montague Island voles and tundra voles from other

island and mainland populations in south coastal

Alaska currently is housed at the University of

Alaska Museum. Sensitive genetic techniques,

such as nuclear DNA sequencing, could be used

to further assess the potential differentiation of the

Montague Island vole.
9

When you

know: Multiply by: To find:

Centimeters (cm) 0.39 Inches

Meters (m) 3.28 Feet

Kilometers (km) 0.62 Miles

Square

 kilometers (km2

) 0.38 Square miles

Hectares (ha) 2.47 Acres

Square

 meters (m2

) 10.76 Square feet

Celsius (o

C) 1.8 and

 add 32 Fahrenheit

Investigation into the extent of infection and effects

of babesiosis on the demography of Montague

Island voles is necessary to effectively assess

their population status. Moreover, because the

squirrel tick (Ixodes angustus), which carries the

Babesia microti blood parasite, can use numerous

animals to complete its life cycle, other mammals

should be surveyed for the presence of this tick

and blood parasite. This can be accomplished

through coordination with the Alaska Department

of Fish and Game in Cordova, Alaska, during

hunting and trapping seasons.

Factors that may negatively affect the beach

fringe, which supports most of the tundra vole

population on Montague Island, should be identified.

Critical tundra vole habitat on Montague Island

should be mapped. Snowfall data should be

collected concurrent with population index data to

reduce the risk of misinterpretation of population

trends.

English Equivalents
10

References

Alaska Board of Game. 1990. Alaska State hunting regulations No. 31. Juneau, AK: Alaska Department of Fish and Game. 47 p.

Alaska Board of Game. 1994. Alaska State hunting regulations No. 35. Juneau, AK: Alaska Department of Fish and Game. 112 p.

Alaska Native Claim Settlement Act [ANCSA] of 1971; 85 stat. 688; U.S.C. 1601 et seq.

Allaby, M., ed. 1994. The concise Oxford dictionary of ecology. Oxford: Oxford University Press.

415 p.

Batzli, G.O. 1985. Nutrition. In: Tamarin, R.J., ed. Biology of New World Microtus. Special Publication No. 8. Shippensburg, PA: The American Society of Mammalogists: 779-811.

Batzli, G.O. 1992. Dynamics of small mammal populations: a review. In: McCullough, D.R.; Barrett,

R.H., ed. Wildlife 2001: populations. London: Elsevier Applied Science: 831-850.

Bee, J.W.; Hall, E.R. 1956. Mammals of northern Alaska. Misc. Publ., Lawrence, KS: Museum of

Natural History, University of Kansas. 309 p.

Brower, W.A.; Baldwin, R.G.; Williams, C.N. [and others]. 1988. Climate atlas of the outer

continental shelf waters and coastal regions of Alaska. Gulf of Alaska. Revision. Anchorage, AK:

University of Alaska, Arctic Environmental Information and Data Center. 544 p. Vol. 1.

Buchalczyk, T.; Pucek, Z. 1978. The succession of small mammals in a drained peat-bog. In:

Abstracts Papers. Brno, Czechoslovakia: Second Congress Theriological International: 193.

Burris, O.E.; McKnight, D.E. 1973. Game transplants in Alaska. Tech. Bull. 4. Juneau, AK: Alaska

Department of Fish and Game. 57 p.

Burt, W.H.; Grossenheider, R.P. 1976. A field guide to the mammals. Boston: Houghton Mifflin Co.

289 p.

Cameron, A.W. 1958. Mammals of the islands in the Gulf of St. Lawrence. Bulletin of the National

Museum Canada. 154: 1-165.

Cameron, A.W. 1964. Competitive exclusion between the rodent genera Microtus and Clethrionomys.

Evolution. 18: 630-634.

Case, T.J. 1978. A general explanation for insular body size trends in terrestrial vertebrates. Ecology.

59: 1-18.

Choate, J.R.; Williams, S.L. 1978. Biogeographic interpretation of variation within and among

populations of the prairie vole, Microtus ochrogaster. Occasional Pap. 49. Lubbock, TX: Museum,

Texas Tech University.

Cole, F.R.; Batzli, G.O. 1978. The influence of supplemental feeding on a population of the prairie

vole Microtus ochrogaster. Journal of Mammalogy. 59: 809-819.

Cornely, J.E. 1999. Tundra vole. In: Wilson, D.E.; Ruff, S., eds. The Smithsonian book of North

American mammals. Singapore: The Smithsonian Institution Press: [Pages unknown].

Crowely, D. 1999. Personal communication. Area biologist, Alaska Department of Fish and Game, P.O.

Box 669, Cordova, AK 99664.
11

Dieterich, R.A.; Preston, D.J. 1977. The tundra vole (Microtus oeconomus) as a laboratory animal.

Laboratory Animal Science. 27: 500-506.

Fay, F.H.; Rausch, R.L. 1969. Parasitic organisms in the blood of arvicoline rodents in Alaska. The

Journal of Parasitology. 55: 1258-1265.

Foster, J.B. 1963. The evolution of the native land mammals of the Queen Charlotte Islands and the

problem of insularity. Vancouver, BC: University of British Columbia. 210 p. Ph.D. dissertation.

Gaines, M.S. 1985. Genetics. In: Tamarin, R.H., ed. Biology of New World Microtus. Special Publication No. 8. Shippensburg, PA: The American Society of Mammalogists: 845-883.

Gaines, M.S.; McClenaghan, L.R., Jr. 1980. Dispersal in small mammals. Annual Review Ecological Systematics. 11: 163-196.

Gehrels, G.E.; Saleeby, J.B. 1987. Geologic framework, tectonic evolution, and displacement history

of the Alexander terrane. Tectonics. 6: 151-173.

Getz, L.L. 1985. Habitats. In: Tamarin, R.H., ed. Biology of New World Microtus. Special Publication

No. 8. Shippensburg, PA: The American Society of Mammalogists: 286-309.

Grant, P.R. 1971. The habitat preference of Microtus pennsylvanicus, and its relevance to the distribution of this species on islands. Journal of Mammalogy. 52: 351-361.

Hall, E.R. 1981. The mammals of North America. 2nd ed. New York: John Wiley: 792-802.

Hanley, T.A.; Rose, C.L. 1987. Influence of overstory on snowdepth and density in hemlock-spruce

stands: Implications for management of deer habitat in southeastern Alaska. Res. Note PNW-RN-459.

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

11 p.

Heller, E. 1910. Mammals of the 1908 Alexander expedition, with descriptions of the localities visited

and notes on the flora of the Prince William Sound region. University of California Publications in

Zoology. 5: 321-360.

Heske, E.J.; Ostfeld, R.S. 1990. Sexual dimorphism in size, relative size of testes, and mating systems

in North American voles. Journal of Mammalogy. 71: 510-519.

Heusser, C.J. 1985. Quaternary pollen records from the Pacific Northwest coast: Aleutians to the

Oregon-California boundary. In: Bryan, V.M., Jr.; Holloway, R.G., ed. Pollen records of LateQuaternary North American sediments. Dallas, TX: American Association of Stratigraphic Palynologists: 141-165.

Hoffmann, R.S.; Koeppl, J.W. 1985. Zoogeography. In: Tamarin, R.H., ed. Biology of New World

Microtus. Special Publication No. 8. Shippensburg, PA: The American Society of Mammalogists: 84-115.

Hulten, E. 1968. Flora of Alaska and neighboring territories. Stanford, CA: Stanford University Press.

[Pages unknown].

Jandro, R. 1999. Personal communication. Concor Forest Products, 3501 Denali Street, Suite 202,

Anchorage, AK 99503.

Johnson, J.F.C. 1984. Chugach legends: stories and photographs of the Chugach region. Anchorage,

AK: Chugach Alaska Corporation. [Pages unknown].

Johnson, J. 1999. Personal communication. Chugach Alaska Corporation, 560 East 34th st., Suite 300,

Anchorage, AK 99503.
Kaikusalo, A.; Tast, J. 1984. Winter breeding of microtine rodents at Kilpisjarvi, Finnish Lapland. In:

Merritt, J.F., ed. Winter ecology of small mammals. Special Publication No. 10. Pittsburgh, PA:

Carnegie Museum of Natural History: 243-252.

Karulin, B.E.; Litvin, V.Y.; Nikitina, N.A. [and others]. 1976. A study of activity, mobility and

diurnal range in Microtus oeconomus on the Yamal Penninsula by means of marking with radioactive

cobalt. Zoologicheskii Zhurnal. 55: 1052-1060.

Keller, B.L. 1985. Reproductive patterns. In: Tamarin, R.H., ed. Biology of New World Microtus.

Special Publication No. 8. Shippensburg, PA: The American Society of Mammalogists: 725-778.

Lahr, J.C.; Plafker, G. 1980. Holocene Pacific-North American plate interaction in southern Alaska:

implications for the Yakataga seismic gap. Geology. 8: 483-486.

Lambin, X.; Krebs, C.J.; Scott, B. 1992. Spacing system of the tundra vole (Microtus oeconomus)

during the breeding season in Canada’s western Arctic. Canadian Journal of Zoology. 70: 2068-2072.

Lance, E.W. 1995. Phylogeographic variation and the island syndrome in Holarctic Microtus

oeconomus. Fairbanks, AK: University of Alaska. 83 p. M.S. thesis.

Lance, E.W.; Cook, J.A. 1995. Status report on the Montague Island tundra vole (Microtus

oeconomus elymocetes), a Category II species. Anchorage, AK: U.S. Fish and Wildlife Service,

Ecological Services. [Pages unknown].

Lance, E.W.; Cook, J.A. I998a. Microtus oeconomus (Pallas 1776) Tundra vole. In: Hafner, D.;

Yensen, E.; Kirkland, G.L., Jr., eds. North American rodents. Status survey and conservation action

plan. Gland, Switzerland and Cambridge, UK: International Union for Conservation of Nature and

Natural Resources: 97-99.

Lance, E.W.; Cook, J.A. 1998b. Phylogeography of tundra voles: Beringian region and southcoastal

Alaska. Journal of Mammalogy. 79: 53-65.

Lidicker, W.Z., Jr. 1985. Dispersal. In: Tamarin, R.H., ed. Biology of New World Microtus. Special

Publication No. 8. Shippensburg, PA: The American Society of Mammalogists: 420-454.

MacArthur, R.H.; Wilson, E.O. 1967. The theory of island biogeography. Princeton, NJ: Princeton

University Press. 203 p.

Madison, D.M. 1985. Activity rhythms and spacing. In: Tamarin, R.H., ed. Biology of New World

Microtus. Special Publication No. 8. Shippensburg, PA: The American Society of Mammalogists:

373-419.

Magoun, A.J.; Johnson, W.N. 1991. Wildlife and furbearers in the boreal forest with emphasis on

marten, lynx, and their prey: an annotated bibliography. Galena, AK: U.S. Fish and Wildlife Service.

305 p.

Mobley, C.M.; Haggarty, C.J.; Utermohle, J.C. [and others]. 1990. The 1989 Exxon Valdez

cultural resource program. Anchorage, AK: Exxon Shipping Co. and Exxon Co. USA. 300 p.

Morrison, P.R.; Dieterich, R.; Preston, D. 1976. Breeding and reproduction of fifteen wild rodents

maintained as laboratory colonies. Laboratory Animal Care. 26: 237-243.

Musser, G.G.; Carleton, M.D. 1993. Family Muridae. In: Wilson, D.E.; Reeder, D.M., eds. Mammal

species of the world; a taxonomic and geographic reference. Washington, DC: Smithsonian Institution

Press: 501-527.

12
Nadeau, J.H. 1985. Ontogeny. In: Tamarin, R.H., ed. Biology of New World Microtus. Special

Publication No. 8. Shippensburg, PA: The American Society of Mammalogists: 254-285.

Nadler, C.F.; Zhurkevich, N.M.; Hoffmann, R.S. [and others]. 1978. Biochemical relationships of

the Holarctic vole genera (Clethrionomys, Microtus, and Arvicola (Rodentia:Arvicolinae)). Canadian Journal of Zoology. 56: 1564-1575.

Osgood, W.H. 1906. A new vole from Montague Island, Alaska. Proceedings of the Biological Society

of Washington. 19: 71-72.

Paradiso, J.L.; Manville, R.H. 1961. Taxonomic notes on the tundra vole (Microtus oeconomus) in

Alaska. Proceedings of the Biological Society of Washington. 74: 77-92.

Patton, J.L.; Brylski, P.V. 1987. Pocket gophers in alfalfa fields: causes and consequences of habitat

related body size variation. American Naturalist. 130: 493-506.

Pearson, O.P. 1985. Predation. In: Tamarin, R.H., ed. Biology of New World Microtus. Special

Publication No. 8. Shippensburg, PA: The American Society of Mammalogists: 535-566.

Pruitt, W.O., Jr. 1968. Synchronous biomass fluctuations of some northern mammals. Mammalia.

32: 172-191.

Ristic, M. 1988. In: Babesiosis of domestic animals and man. Boca Raton, FL: CRC Press,

Inc.: 39-40, 217.

Ristic, M.; Kreier, J.P. 1981. Babesiosis. New York: Academic Press. [Pages unknown].

Rose, R.K.; Birney, E.C. 1985. Community ecology. In: Tamarin, R.H., ed. Biology of New World

Microtus. Special Publication No. 8. Shippensburg, PA: The American Society of Mammalogists:

310-339.

Smith, M.F.; Patton, J.L. 1988. Subspecies of pocket gophers: causal bases for geographic differentiation in Thomomys bottae. Systematic Zoology. 37: 163-178.

Snyder, N.F.R.; Wiley, J.W. 1976. Sexual size dimorphism in hawks and owls in North America.

North American Ornithological Monograph. 20: 1-96.

Taitt, M.J.; Krebs, J.C. 1985. Population dynamics and cycles. In: Tamarin, R.H., ed. Biology of

New World Microtus. Special Publication No. 8. Shippensburg, PA: The American Society of Mammalogists: 567-620.

Tast, J. 1966. The root vole, Microtus oeconomus, as an inhabitant of seasonally flooded land.

Annales Zoologici Fennici. 3: 127-171.

Tast, J. 1984. Winter success of root voles, Microtus oeconomus, in relation to population density and

food conditions at Kilpisjarvi, Finnish Lapland. In: Merritt, J.F., ed. Winter ecology of small mammals.

Special Publication No. 10. Pittsburgh, PA: Carnegie Museum of Natural History: 59-66.

Tast, J.; Kaikusalo, A. 1976. Winter breeding of the root vole, Microtus oeconomus, in 1972/1973 at

Kilpisjarvi, Finnish Lapland. Annals Zoological Fennica. 13: 174-178.

U.S. Department of Agriculture, Forest Service. 1989. Big Island Management Area, final environmental impact statement. R10-MB-76. Anchorage, AK: Chugach National Forest. [Pages unknown].

U.S. Department of Agriculture, Forest Service. 1990. Regional Forester’s sensitive species list.

Unpublished document. On file with: Alaska Regional Office, P.O. Box 21628, Juneau, AK 99802-1628.

13
U.S. Department of Agriculture Forest Service. 1993. Unpublished data. On file with: U.S.

Department of Agriculture, Forest Service, Chugach National Forest, Management of Resource

Information Group, 3301 “C” St., Suite 300, Anchorage, AK 99503-3998.

U.S. Fish and Wildlife Service. 1991. Animal candidate review. Federal Register (58 FR 51144).

Viereck, L.A.; Dyrness, C.T.; Batten, A.R.; Wenzlick, K.J. 1992. The Alaskan vegetation classification. Gen. Tech. Rep. PNW-GTR-286. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 278 p.

Weintraub, E.; Cook, J.A. 1991. Taxonomic status and ecology of the Montague Island tundra vole

(Microtus oeconomus elymocetes). Report on file with: Cordova Ranger District, Chugach National

Forest, Cordova, AK 99574.

Weintraub, E.; Cook, J.A. 1992. Taxonomic status and ecology of the Montague Island vole (Microtus

oeconomus elymocetes). Cordova, AK: Chugach National Forest, Cordova Ranger District.

West, E. 1991. Personal communication. Zoologist, The Nature Conservancy, Alaska Natural Heritage

Program, 707 “A” Street, Anchorage, AK 99501.

Wetzel, R.M. 1958. Mammalian succession in midwestern floodplains. Ecology. 39: 262-271.

Whitney, P. 1976. Population ecology of two sympatric species of subarctic microtine rodents. Ecological Monographs. 46: 85-104.

Whitney, P. 1977. Seasonal maintenance and net production in two sympatric species of subarctic

microtine rodents. Ecology. 58: 314-325.

Yarborough, L.F. 1999. Personal communication. Archeologist, Chugach National Forest, 3301 “C”

Street, Suite 300, Anchorage, AK 99503.

Youkey, D.E. 1992. Snow surveys on the Copper River Delta. Report on file with: Cordova Ranger

District, Chugach National Forest, Cordova, AK 99574. [Pages unknown].

Youkey, D.E. 1999. Personal communication. Wildlife biologist, Juneau Ranger District, 8465 Old

Dairy Rd., Juneau, AK 99801-8041.

Youngman, P.M. 1975. Mammals of the Yukon Territory. National Museum of Natural Science

(Ottawa), Publication in Zoology. 10: 1-189.

Zimmermann, K. 1942. Zurkenntnis von Microtus oeconomus (Pallus). Archiv fur Natururgesch,

Bd11, Heft. 2: 175-189.

14
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