United States

Department of

Agriculture

Forest Service

Pacific Northwest

Research Station

General Technical

Report

PNW-GTR-384

November 1996

The Alexander Archipelago

Wolf: A Conservation

Assessment

David K. Person, Matthew Kirchhoff,

Victor Van Ballenberghe, George C. Iverson,

and Edward Grossman
Authors DAVID K. PERSON is a graduate fellow, Alaska Cooperative Fish and Wildlife

Research Unit at the University of Alaska Fairbanks, Fairbanks, AK 99775;

MATTHEW KIRCHHOFF is a research wildlife biologist, Alaska Department of Fish

and Game, P.O. Box 240020 Douglas, AK 99824; VICTOR VAN BALLENBERGHE is

a research wildlife biologist, U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station, Forestry Sciences Laboratory, 3301 C Street, Suite 200,

Anchorage, AK 99503-3954; GEORGE C. IVERSON is the regional ecology program

leader, U.S. Department of Agriculture, Forest Service, Alaska Region, P.O. Box

21628, Juneau, AK 99801; and EDWARD GROSSMAN is a wildlife biologist with the

U.S. Department of the Interior, Ecological Services, 3000 Vintage Boulevard Suite

205, Juneau, AK 99801.
Conservation and Resource

Assessments for the Tongass Land

Management Plan Revision

Charles G. Shaw III

Technical Coordinator

The Alexander Archipelago Wolf:

A Conservation Assessment

David K. Person

Matthew Kirchhoff

Victor Van Ballenberghe

George C. Iverson

Edward Grossman

Published by:

U.S. Department of Agriculture

Forest Service

Pacific Northwest Research Station

Portland, Oregon

General Technical Report PNW-GTR-384

November 1996

In cooperation with:

U.S. Fish and Wildlife Service

Alaska Department of Fish and Game
Abstract Person, David K.; Kirchhoff, Matthew; Van Ballenberghe, Victor; Iverson,

George C.; Grossman, Edward. 1996. The Alexander Archipelago wolf: a

conservation assessment. Gen. Tech. Rep. PNW-GTR-384. Portland, OR: U.S.

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

42 p. (Shaw, Charles G., III, tech. coord.; Conservation and resource assessments

for the Tongass land management plan revision).

We summarized the scientific information available for the Alexander Archipelago

wolf (Canis lupus ligoni) in the Tongass National Forest of southeast Alaska. Information concerning the morphology, distribution, taxonomy, genetics, and ecology

of wolves are presented. Three issues for the conservation of wolves in southeast

Alaska are discussed: loss of long-term carrying capacity for deer due primarily to

extensive timber harvesting, increased mortality of wolves associated with improved

human access from roads, and continued high levels of harvest of wolves by humans.

Continued timber harvesting at current levels and by current methods will likely have

adverse consequences for some segments of the wolf population. Although some

short-term regulatory changes and the management of road access may need to be

considered to keep wolf harvest at a sustainable level, the most important consideration is to maintain long-term carrying capacity for deer, the principal prey for most of

the wolf population. A series of old-growth forest reserves may provide an effective

strategy to increase the likelihood that wolves will persist where extensive timber

harvesting has occurred, or is planned.

Keywords: Alexander Archipelago wolf, Canis lupus ligoni, effects of logging on

wildlife, population dynamics of wolves, predator-prey dynamics, roads and wolf

mortality, Tongass National Forest, southeast Alaska.

Summary The Alexander Archipelago wolf (Canis lupus ligoni) occupies most of southeast

Alaska from Yakutat Bay to Dixon Entrance except for Admiralty, Baranof, and

Chichagof Islands. Based on common cranial characteristics, the Alexander

Archipelago wolf was considered by early taxonomists to be a distinct subspecies.

Recent taxonomic work suggests that these wolves may have originated from a

larger subspecific group (C. l. nubilus) that at one time inhabited most of the

contiguous Western United States. Wolves probably entered southeast Alaska

sometime after the Wisconsin glaciation, following the northward expansion of

black-tailed deer (Odocoileus hemionus) along the coast. The hypothesis of a

southern origin is supported by recent genetic research showing that wolves in

southeast Alaska share a common allele not found in a sample of wolves from

interior Alaska or the Yukon. The population is relatively isolated from other wolf

populations by water and mountain barriers.

A study of the ecology of wolves in southeast Alaska was conducted on Prince

of Wales and Kosciusko Islands from 1992 to 1995. Average home-range size of

radio-telemetered wolves was 280 square kilometers (109 mi2

), with 75 percent of

the radio locations for each pack within “core areas” averaging 124 square kilometers

(48 mi2

). Pack sizes ranged from 2 to 12, with 7 to 9 typical in early autumn. Annual

rates of dispersal averaged 39 percent; 71 percent of dispersers were adults ≥2 years

old. Dispersal distances were relatively short (13 to 182 kilometers [5 to 71 mi]) presumably due to inter-island water barriers. Wolf movements were more restricted

during the denning and pup-rearing season (mid-April through August), when home

ranges were 50 percent smaller than in winter. Of the 14 dens located in this study,

all were in old-growth forest within 100 meters (328 feet) of fresh water. One den

was under a large log; all others were in cavities beneath the roots of large trees.
Sitka black-tailed deer (O. h. sitkensis) were the primary prey of wolves. Deer remains

occurred in 90 percent of wolf feces (scats) examined from Prince of Wales Island.

Deer occurred exclusively in 45 percent of the scats. The only other prey occurring

with >10 percent frequency was beaver (Castor canadensis). Other prey consumed

in small quantities included black bears (Ursus americanus), mustelids, other small

mammals, birds, and salmon (Oncorhynchus spp.). Using information on diet composition, consumption rates, and body size of prey, we estimated that wolves on

islands in southern southeast Alaska consumed an average of 26 deer per wolf per

year (SE = 4.1).

Most of the wolves in southeast Alaska occur on the large islands south of Frederick

Sound. These islands (game management units 2 and 3) support approximately 60

to 70 percent of the total population. By extrapolating from empirical population estimates for Prince of Wales Island, we estimated the autumn 1994 population of wolves

in southeast Alaska at slightly over 900 animals (SE = 216). Hunting, trapping, and

illegal killing accounts for a high percentage of the mortality in wolves. Based on

analysis of trapping and hunting mortality by wildlife analysis area (WAA), we determined that mortality was correlated with the linear kilometers of road within WAAs.

Indeed, reported wolf harvest increased twofold when the length of road below 370

meters (1200 ft) elevation exceeded 95 kilometers (59 mi), regardless of the size

of the WAA. This corresponded to an approximate road density of 0.4 kilometer per

square kilometer (≈0.7 mi/mi2

), most of which were open to human access. Between

1993 and 1995, the average annual mortality in a total sample of 24 radio-collared

wolves on Prince of Wales Island was 50 percent (SE = 13 percent). If applied to the

overall wolf population on Prince of Wales Island, this rate of mortality would not be

sustainable.

Wolf populations are closely tied to population levels of their ungulate prey. For

southeast Alaska, we predicted the number of deer required per wolf to attain

equilibrium between deer and wolves by using a Monte Carlo simulation of a model

that calculated equilibrium ratios for wolves and their ungulate prey. We assumed a

high average finite rate of increase for deer (1.3), a mean predation rate of 26 deer

per wolf per year, and a human harvest of deer equal to 21 percent of the annual

increment. Our results suggest that 170 to 180 deer per wolf are needed for a

95-percent probability of equilibrium, provided that mortality of deer due to predation is primarily additive. We cannot suggest a minimum deer population because we

do not know what would constitute a minimum viable wolf population either demographically or genetically. Nevertheless, if we expect to sustain the current postdenning population of 250 to 300 wolves on Prince of Wales Island (along with subsistence and sport harvests of deer) with a high probability of attaining equilibria, then

sufficient habitat is needed to support 42,500 to 54,000 deer.

Our review raises a number of issues concerning the long-term sustainability of

wolves in southeast Alaska. Many more data are needed on wolf population structure,

genetic structure, and predator-prey relations to fully address these issues and the

overall question of viability. The Alexander Archipelago wolf exists in small numbers

in a rapidly changing insular environment. Projected growth in human population,

increasing road access, and the continuing loss and fragmentation of high-quality

deer habitat will increase the risk of not maintaining a viable, well-distributed population of wolves in southeast Alaska. The area of most immediate concern is game

management unit 2, including Prince of Wales and Kosciusko Islands.
Management actions that address risks to wolf populations include modifying hunting

and trapping regulations as necessary, limiting construction of new roads and effectively closing some existing ones, and modifying timber harvest strategies to minimize

fragmentation and loss of critical deer winter range. Habitat to support a minimum

density of 5 deer per square kilometer (13 deer/mi2

), where deer are the primary prey

for wolves, would provide for current levels of deer harvest by hunters, trappers, and

wolves. In areas less productive for deer, maintaining current densities of deer is

particularly important. Setting aside contiguous blocks of habitat within each biogeographic province that are large enough to encompass at least one wolf pack core

home range (200 square kilometers [76 mi2

]) would markedly increase the likely

persistence of wolves, especially if the reserves contain high-quality deer habitat

sufficient to support an average density of deer equal to 7 deer per square kilometer

(18 deer/mi2

). The objective of maintaining undisturbed blocks of habitat within each

biogeographic province is to assure the persistence of several wolf packs that will

serve as source populations capable of replacing wolves that periodically disappear

from adjacent disturbed lands.

Purpose and Need In 1990, wolves in southeast Alaska were identified by a USDA Forest Servicesponsored interagency committee as a species for which there may be concerns

about viability or distribution as a result of extensive timber harvesting in the Tongass

National Forest.1 In December 1993, the Biodiversity Legal Foundation (Boulder,

CO) and an independent biologist from Haines, AK, filed a petition with the U.S. Fish

and Wildlife Service (FWS) requesting that wolves in southeast Alaska be listed as

a threatened subspecies pursuant to the Endangered Species Act of 1973, as

amended. The FWS ruled that listing was not warranted at this time, but added:

“However, it is clear by our analysis that without significant changes to the existing

Tongass Land Management Plan, the long-term viability of the Alexander Archipelago

wolf is seriously imperiled.”2 Following that notice, this assessment was prepared

under the auspices of the memorandum of understanding among the Forest Service,

Alaska Department of Fish and Game, and the Fish and Wildlife Service. They, along

with the Regional Forester, Alaska Region, requested that a conservation assessment be prepared to summarize available scientific information on the status and

ecology of wolves in southeast Alaska, and to identify issues regarding their longterm viability and distribution.

1 Suring, L.; Crocker-Bedford, D.C.; Flynn, R.W. [and others].

1993. A proposed strategy for maintaining well-distributed,

viable populations of wildlife associated with old-growth

forests in southeast Alaska. Review draft. 278 p. On file

with: U.S. Department of Agriculture, Forest Service, Alaska

Region, P.O. Box 21628, Juneau, AK 99802-1628.

2 U.S. Fish and Wildlife Service. 1994. Report on petition

to list the Alexander Archipelago wolf under provision of

the Endangered Species Act, 12 month finding; under

signature of Mollie Beattie, Director. 25 p. (p. 19). On

file with: Alaska Department of Fish and Game, Douglas,

AK 99824.
This conservation assessment was chartered under the Tongass [National Forest]

Land Management Plan revision and the interagency memorandum of understanding

(MOU) among the Alaska Region of the Forest Service, the Alaska Region of the

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

conserve species tending toward listing.3 Our report summarizes the most current

information available on the taxonomy, genetics, distribution, ecology, and population

dynamics of wolves in southeast Alaska. Much of the information has not been published. In particular, we have drawn heavily from ongoing studies on wolves in southeast Alaska that is cosponsored by the USDA Forest Service, the Alaska Department

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

Fairbanks. Results from that work are preliminary.

Contents

3 The primary objective of the MOU was to foster interagency cooperation for the conservation of candidate and

sensitive species to avoid the need for listing and protection

under the Endangered Species Act. The wolf, in addition to

the marbled murrelet (Branchyramphus mamoratus) and

northern goshawk (Accipter gentilis), was identified as

a priority species for conducting a conservation assessment to achieve MOU objectives.

1 Background

1 A Brief Description of Southeast Alaska

1 Description and Distribution of Alexander Archipelago Wolves

4 Taxonomy

5 Genetics

7 Ecology

20 Wolf Conservation

21 Prey Populations

22 Roads

26 Exploitation

27 Conclusions

31 Acknowledgments

31 References

39 Appendix 1

40 Appendix 2

42 Appendix 3
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Document continues on next page.
Background

A Brief Description of

Southeast Alaska

Southeast Alaska comprises a narrow strip of mainland and a chain of islands known

as the Alexander Archipelago wedged between the Pacific Ocean and the Coast

Mountains of Canada (fig 1). The archipelago includes hundreds of islands ranging in

size from less than 1 hectare (2.4 acres) to over 6,000 square kilometers (2,340 mi2

)

that extend over 500 kilometers (310 mi) in a line parallel to the mainland. Elevations

less than 800 meters (≈2,500 ft) are covered by temperate rain forests of Sitka spruce

(Picea sitchensis (Bong.) Carr.), western hemlock (Tsuga heterophylla (Raf.) Sarg.),

western redcedar (Thuja plicata Donn ex D. Don), and Alaska-cedar (Chamaecyparis

nootkatensis (D. Don) Spach.) interspersed with muskegs. Subalpine and alpine

zones of vegetation exist above 800 meters (≈2,600 ft), with the highest elevations

covered by rock and ice. Several river drainages connect the region to interior British

Columbia and the Yukon. Weather conditions are highly variable, with annual precipitation ranging between 130 and 400 centimeters (≈50 to 160 in). Accumulation of

snow is greatest on the mainland and northernmost islands and becomes intermittent

in the southern portion of the archipelago. About 80 percent of the land in southeast

Alaska is contained within the Tongass National Forest, the largest National Forest

in the United States.

Description and

Distribution of

Alexander Archipelago

Wolves

Based on a sample of 37 wolves representing most of the Alexander Archipelago

and the adjacent mainland, taxonomist E.A. Goldman described the Alexander

Archipelago wolf (Canis lupus ligoni) as smaller, shorter haired, and darker in normal

coloration than wolves in northern and interior areas of Alaska (Goldman 1944).

Wood (1990) also described the Alexander Archipelago wolf as smaller with shorter

and coarser hair than interior Canadian or Alaskan wolves. On islands in the southern

portion of the archipelago, a black color phase constitutes about 20 percent of the

population, gray or brown about 80 percent, and white or nearly white wolves less

than 1 percent (Wood 1990). On the northern mainland, the black color phase is

more common, accounting for about 50 percent of the wolves in the harvest (Morgan

1990). Adult wolves in southeast Alaska weigh an average of 39.5 kilograms (87 lb),

with females weighing about 6.8 kilograms (15 lb) less than males (Alaska Department of Fish and Game [ADFG] 1960, Wood 1990). Wolves from some of the major

island groups in the archipelago may be somewhat smaller than the average for

the region. For example, adults from a sample of 24 radio-collared wolves from

Kosciusko and Prince of Wales Islands averaged 34 kilograms (75 lb) (n =11,

SE = 4.5 kilograms [10 lb]), with females weighing about 1 kilogram (2.2 lb) less

than males (Person and Ingle 1995).

Wolves occur on the mainland and all larger islands in southeast Alaska except

Admiralty, Baranof, and Chichagof Islands (fig. 2). Klein (1965) hypothesized that

wolves colonized the region from the south following the postglacial northward

expansion of black-tailed deer (Odocoileus hemionus). Carbon-14 dates of fossil

bones from deer found on Prince of Wales Island suggest that deer arrived at least

8,000 years B.P. (Jull 1993). Although most of the islands in the southern half of the

archipelago are used by wolves, only the largest, including Prince of Wales, Kuiu,

Kupreanof, Mitkof, Etolin, Revillagigedo, Kosciusko, and Dall Islands, likely support

packs of wolves that persist longer than a few years. For example, Prince of Wales

and the islands immediately adjacent to it (including Kosciusko and Dall Islands)

1
Figure 1—Southeast Alaska and the Tongass National Forest (USDA Forest Service 1991).

2
constitute game management unit 2 (GMU 2, fig. 2), so-designated by the ADFG.

Within GMU 2, only the three largest islands—Prince of Wales, Kosciusko, and

Dall—are known to have been continuously occupied by wolves for more than

20 years (Person and Ingle 1995). Wolf packs may include several smaller islands

(e.g., Baker, Lulu, Noyes, Tuxekan, Marble, Thorne) in their home ranges or may

exclusively inhabit smaller islands for a few years, but they are unable to persist

permanently (Klein 1996, Person and Ingle 1995).

From a continental perspective, wolf populations in southeast Alaska are relatively

isolated. The Coast Mountains to the east are glaciated or snow-covered year-round,

and only six rivers or passes penetrate the 800 kilometers-long (500-mi) cordillera.

The most significant of these are the Stikine, Taku, Whiting, and Unuk Rivers.

Although no direct evidence exists regarding the dispersal of wolves through these

passes or river valleys, wolves do occur in the valleys, and some level of interchange between interior Canada and the coast may occur. Nevertheless, the significant morphological differences between southeast Alaskan wolves and wolves

from interior Canada and Alaska (Friis 1985, Nowak 1983, Pedersen 1982) suggest

that the level of interchange is small or admixture has occurred only recently.

Figure 2—Distribution of Alexander Archipelago wolves in southeast Alaska. Wolves occupy areas shown

in black. Map also shows game management units (GMUs) in southeast Alaska.

3
Within the Alexander Archipelago, dispersal of wolves among individual islands (or

island groups) probably is restricted by water barriers. The absence of wolves (or

wolf fossils) on the northern islands of the archipelago attests to the effectiveness

of Frederick Sound, Stephen’s Passage, and Icy Strait as barriers to movement by

wolves. Dense populations of brown bears (Ursus arctos) on Admiralty and Chichagof

Islands also may contribute to the lack of successful colonization by wolves. Clarence

Strait, which runs north-south along the eastern shore of Prince of Wales Island,

restricts movement from the mainland and from Revillagigedo Island to GMU 2.

Although wolves may reach Prince of Wales Island from the mainland via a chain

of stepping-stone islands at the north end of Clarence Strait, at least eight directed

swims (some 1.6 to 3.2 kilometers [1 to 2 mi] long) would be needed to complete

such a crossing. Evidence exists suggesting that wolves are capable of swimming

up to 4 kilometers (2.5 mi; Person and Ingle 1995), but the shapes and distribution

of land masses, currents, and the high frequency of storms combine with distance

to impede dispersal among the major island groups in the archipelago. Exchange

between mainland and island populations is probably greatest in the vicinity of Mitkof

Island and the Stikine River Delta, where the swimming distance is short at low tide.

Water barriers between some major island groups and the mainland also could limit

interchange between these island wolves and wolves immigrating from interior Alaska

or Canada.

Wolves in southeast Alaska are legally hunted and trapped. A maximum of five

wolves per hunter may be shot from 1 August to 30 April. Trappers may harvest

wolves from 10 November to 30 April with no bag limit. The annual reported harvest

in southeast Alaska from 1990 to 1995 has averaged about 194 wolves (SE = 35,

GMUs 1 to 5). Hunting and trapping seasons are regulated and administered by the

ADFG through the Board of Game. Subsistence hunting and trapping on Federal

public lands are regulated and administered by the Federal Subsistence Board.

State and Federal regulations regarding wolf harvest currently are identical.

Taxonomy Early taxonomists recognized 24 subspecies of gray wolves (Canis lupus) in North

America (Goldman 1944, Hall 1981) based on morphometric analyses of skull characteristics. Wolves from southeast Alaska were included in this classification as a

subspecies, C. l. ligoni, unique to the Alexander Archipelago; their range extended

from Dixon Entrance north to Yakutat Bay including the coastal mainland and all

islands south of Frederick Sound. Pedersen (1982) performed an extensive

morphometric analysis of wolves in Alaska by using a transect sampling strategy

to determine if the four Alaskan subspecies (C. l. pambasileus, C. l. tundrarum,

C. l. alces, and C. l. ligoni) described by Goldman constituted gradual clinal variations or distinct, geographically correlated populations. Pedersen (1982) reported

that the three subspecies from interior Alaska (C. l. pambasileus, C. l. tundrarum,

and C. l. alces) are indistinguishable from each other and probably represented clinal

variation within a single population, but concluded that the abrupt morphometric differences between C. l. ligoni and interior Alaskan wolves suggest that wolves from

4
southeast Alaska are a distinct population, possibly warranting subspecific classification. Nowak (1983) and Friis (1985) also concluded that C. l. ligoni is morphometrically distinct from interior Alaskan and Canadian wolves; nevertheless, both authors

suggested that the Alexander Archipelago wolf is related to wolves that historically

occupied coastal British Columbia, Vancouver Island, and the contiguous Western

United States. Nowak (1996) recently proposed a revised taxonomy for extant populations of wolves in which C. l. ligoni is considered an isolated population of C. l.

nubilus (fig. 3), a subspecies including wolves in central Canada and Minnesota.

This latest taxonomic revision is likely to be the most widely accepted system among

biologists and taxonomists. Regardless of the subspecific status of C. l. ligoni, morphological data strongly suggest a southern affinity, supporting the hypothesis that

wolves colonized southeast Alaska from the south. As taxonomist Ronald Nowak

(1994) pointed out in his letter:

The original wolf populations of the entire western United States, and probably of coastal

British Columbia, have been extinct for many years. Wolves of another subspecies have

recently expanded into much of southwestern Canada and the northwestern United

States. Essentially, the wolf population of Southeast Alaska is surrounded on one side

by the sea and on the land side by wolves of another subspecies. It is probably isolated

from its nearest living relatives (Minnesota to central Canada) by about 2,000 miles.

The Southeast Alaska wolf population also can be viewed as a remnant U.S. population....It is as distinctive a population segment as can be found among North

American wolves.

Genetics Studies incorporating allozyme electrophoresis of nuclear DNA (Kennedy et al. 1991)

and restriction fragment analysis of mitochondrial DNA (mtDNA; Wayne et al. 1992)

concluded that wolf populations in North America show little genetic differentiation

among geographic regions. Wayne et al. (1992) identified 13 mtDNA genotypes in

a sample of wolves representing most of their current range in North America and

estimated sequence divergence to be small, ranging from 0.10 percent to 0.83 percent. Indeed, one genotype was virtually ubiquitous and occurred in wolves from

Manitoba, northern Alaska, Yukon, Alberta, Montana, and Vancouver Island.

These data from mtDNA contrast with the current taxonomic system that recognizes

24 distinct subspecies of wolves in North America. At the very least, they support the

revised taxonomic system proposed by Nowak (1996) that identifies only five distinct

groups, and may suggest that wolves in North America are a single large population

(Wayne et al. 1992). Nonetheless, genetic data are based primarily on results from

restriction fragment analysis of mtDNA, which is informative only above the level of

0.5 percent genetic divergence (Shields 1995) and may have insufficient resolution

to detect recent divergence in wolf populations. Further, none of the genetic studies

included C. l. ligoni in the samples.

5
Results from a preliminary genetic analysis of mtDNA from C. l. ligoni identified a

fixed allelic substitution in wolves from southeast Alaska distinct from those surveyed

in northern Alaska and the Yukon (Shields 1995). In addition, genetic variation at

eight other nucleotides within the mtDNA genomes of northern Alaska and Yukon

wolves was not observed in any of the samples from southeast Alaskan wolves.

This study used direct sequencing of a 310-base pair portion of the control region

of PCR-amplified mtDNA, which is capable of detecting any genetic variation existing

within the segment of the mtDNA genome surveyed. These data are significant

because only a small portion of the mtDNA genome (<2 percent) was analyzed,

thereby suggesting that additional genetic variation may exist within the entire

genome. Nonetheless, sample sizes were small. Only 38 samples (29 from southeast

Alaska, 9 from northern Alaska and the Yukon) from a total of 50 yielded amplified

DNA adequate for analysis. A larger sample of wolves from outside southeast Alaska

may reveal a closer affinity between C. l. ligoni and other Alaskan and Canadian

wolves; nonetheless, data currently available suggest that the Alexander Archipelago

wolf is distinct from wolves in northern Alaska and the Yukon (Shields 1995). The

genetic relations between C. l. ligoni and wolves from coastal and interior British

Columbia, Montana, and Minnesota have not been investigated. Shields (1995)

speculates, based on the revised wolf taxonomy of Nowak (1996), that the Alexander

Archipelago wolf may show genetic affinity with historic wolf populations from coastal

British Columbia and Vancouver Island.

Figure 3—Current distribution of gray wolf subspecies in North

America reflecting the revised taxonomy proposed by Nowak

(1996): (1) Canis lupus arctos, (2) C. l. baileyi, (3) C. l. lycaon,

(4) C. l. nubilus, and (5) C. l. occidentalis. Map is adapted from

Nowak (1996) and range boundaries are approximate.

6
Shields (1995) observed no evidence that genetically unique subpopulations of

wolves occur on individual islands within the Alexander Archipelago. One DNA

cytotype occurred on six different islands, thereby suggesting that some gene flow

exists across water barriers. Alternatively, 12 DNA cytotypes occurred among Alexander Archipelago wolves, indicating that genetic diversity was not being reduced by

bottlenecking (Shields 1995). These data are limited because of small sample sizes,

and no analysis of allelic frequency was possible. In addition, analyses of nuclear

DNA, rather than mtDNA, may be necessary to resolve questions about gene flow

and rates of migration within the Alexander Archipelago wolf population. Data suggest that migration events have occurred in the past, but are uninformative about

the frequency of migration because mtDNA genotypes are transmitted intact through

the female germ line and may proliferate in a population through a small number of

matriarchal lines (Lehman et al. 1991).

Ecology Home range and pack size—Wolves are social animals that travel in packs and

actively defend territories from encroachment by other individuals or packs (Mech

1970). In southeast Alaska, minimum convex polygon (MCP) home ranges for wolf

packs on Revillagigedo Island averaged 279 square kilometers (108 mi2

; range 79 to

447 square kilometers [30 to 170 mi2

], n = 7; Smith et al. 1987). On Prince of Wales

and Kosciusko Islands, pack home ranges (average of 95-percent adaptive kernel

[Worton 1989] and 95-percent MCP home ranges) based on a minimum of 40 independent radio locations averaged 280 square kilometers (109 mi2

; range 101 to 419

square kilometers [39 to 163 mi2

], n = 7; Person, in prep.). Core areas where wolf

activity was concentrated, were estimated to be 124 square kilometers (48 mi2)

and were 55 to 60 percent smaller than total home ranges (based on the average

of 75 percent adaptive kernel and 75 percent MCP home ranges).

MCP home ranges of packs (based on a minimum of 40 independent radio locations)

during the denning and pup-rearing period (15 April-1 August) were about 50 percent

smaller than during other times of the year (Person and Ingle 1995). This result contrasts with other studies that note wolf home ranges during summer and winter to be

similar in size (Fritts and Mech 1981, Fuller 1989, Potvin 1988, Van Ballenberghe et

al. 1975). Summer home ranges reported for wolves on Prince of Wales Island were

not unusually small when compared with summer home ranges reported elsewhere

for well-established wolf packs that primarily preyed on deer; however, winter home

ranges were substantially larger than those reported in other studies. For example,

Fuller (1989) reports average winter and summer home ranges of 116 and 110

square kilometers (45 and 43 mi2

), respectively, for wolves in a portion of Minnesota

where deer density was high. On Prince of Wales Island, summer home ranges for

five wolf packs averaged about 100 square kilometers (39 mi2

) whereas winter home

ranges for the same packs averaged about 240 square kilometers (93 mi2

; Person,

in prep.).

Pack sizes on Revillagigedo Island averaged 5.4 wolves (range 2 to 12, n = 8; Smith

et al. 1987). Pack sizes on Prince of Wales and Kosciusko Islands were larger,

averaging 7 to 9 wolves (range = 2 to 12, n = 8; Person and Ingle 1995) in early

autumn before the trapping season. Pack size and composition can change over

time, with individuals or small groups of wolves occasionally splitting from the main

pack, only to rejoin it days or weeks later (Person, in prep.). Indeed, all members of

a wolf pack rarely are observed together, except during winter. Pack sizes are difficult

to estimate unless repeated, direct observations are made.

7
Food habits—Wolves prey on large ungulates such as deer, mountain goats

(Oreamnos americanus), moose (Alces alces), caribou (Rangifer tarandus), and elk

(Cervus elaphus) (Mech 1970). In southeast Alaska, deer are the primary prey on the

islands and portions of the mainland (Garceau 1960, Kohira 1995, Smith et al. 1987).

In areas of the mainland where deer are scarce, important prey include beaver

(Castor canadensis), mountain goat, and moose (Smith et al. 1986a, Wood 1990).

Wolves in southeast Alaska have access to spawning salmon during late summer

and early autumn (Kohira 1995, Smith et al. 1986b, Wood 1990). Wolves also feed

opportunistically on harbor seals (Phoca vitulina), mustelids, small mammals, birds,

and marine invertebrates (Garceau 1960; Kohira 1995; Merriam 1966, 1968; Smith

et al. 1986b).

Data from 182 microscopically examined wolf scats collected between autumn 1992

and autumn 1994 on Prince of Wales Island showed deer remains in 90 percent of

the scats (Kohira 1995). Deer occurred exclusively in 45 percent of the scats, but

often were found in conjunction with beaver (30 percent of the scats). The remains

of beaver, the only other prey species that occurred with >10 percent frequency,

were found in 31 percent of the scats, with the highest incidence occurring during

late spring. Only one scat contained exclusively beaver remains. Other prey consumed in small quantities included black bear (Ursus americanus), mink (Mustela

vison), marten (Martes americana), river otter (Lutra canadensis), small mammals,

birds, and fish (Kohira 1995).

In a sample of 363 scats from Revillagigedo Island, 74 percent and 20 percent of

the scats contained deer and beaver remains, respectively (Smith et al. 1987). About

30 percent of the scats collected in summer contained remains of fawns, accounting

for 41 percent of all scats containing deer.

We combined the data from Prince of Wales and Revillagigedo Islands (n = 545

scats) and estimated the percentage of prey species by volume in the diet by using

a regression model described by Floyd et al. (1978) and later modified by Weaver

(1993). Results of a Monte Carlo simulation (n = 1,000) of the regression function

indicated that 77 percent (SE = 10 percent) of the diet was composed of deer. Beaver

composed only 13.7 percent (SE = 9 percent) of the diet, and all other species

contributed <10 percent. These data strongly suggest that wolves occurring on the

islands of southeast Alaska depend on the availability of deer and raise questions

about the ability of alternative prey to sustain wolves in the absence of deer.

Population dynamics—

Reproduction and denning—Age of first breeding is about 22 to 34 months, and

litters of 3 to 7 young usually are produced (Mech 1970, Stephenson 1989). Most

packs include a pair of breeding adults plus adults that may or may not breed.

Mean litter sizes in Alaska, as indicated by counts of blastocysts, range from

4.6 to 7.2, depending on prey availability per wolf (Boertje and Stephenson 1992,

Gasaway et al. 1992). The reproductive potential of wolves is high, and natural or

human-caused mortality, rather than the failure of a pack to breed or produce pups,

often is the major factor limiting the growth of wolf populations (Fuller 1989, Rausch

1967).

Wolves in southeast Alaska use dens, or areas near dens, from mid-April through

early July. Activity peaks around den sites from early May to the third week in June.

Of 14 den sites examined between October 1992 and October 1995, all were in

8
old-growth forest within 100 meters (330 ft) of fresh water (Person and Ingle 1995).

One den was under a large log; all others were in cavities beneath the roots of large

trees (mean diameter at breast height >90 centimeters [35 in]). Eight of 11 dens

visited during the year they were used were adjacent to ponds or streams with

active beaver colonies.

Litter sizes estimated from direct observations at dens on Prince of Wales Island

ranged from one to six pups ( = 3.7, SE = 1.8, n = 6) during the 1995 denning

period (Person, in prep.). Direct observations made during early autumn revealed

that only one pup from the total number seen at the dens had disappeared, suggesting high pup survivorship during summer. This outcome may be a consequence

of the availability of salmon at the time pups are weaned, enabling them to exploit an

additional food supply at a time when they are inexperienced hunters and occupy

a low position in the dominance hierarchy of the pack.

Mortality—Humans account for a high percentage of mortality in both protected and

heavily exploited wolf populations (Ballard et al. 1987, Fuller 1989, Peterson et al.

1984). In southeast Alaska, 1,163 wolves were reported killed by hunters and trappers

from 1990 to 1995. About 60 percent of the mortality was from trapping (including

snaring) and 40 percent from hunting (i.e., ground shooting).1 The highest reported

mortality occurred in December and January during the peak of the trapping season.

In exploited populations, mortality from natural causes (e.g., starvation, accidents,

disease, and fighting) is small, typically averaging 5 to 10 percent per year (Fuller

1989). A more substantial cause of mortality results from unreported or illegal killing

of wolves by people. Of 17 radio-collared wolves on Prince of Wales Island that died

during a 3-year study, nine (53 percent) were legally killed by humans, five (29 percent) were killed by humans, but not reported, and three (18 percent) died from

natural causes (Person, in prep.). Considering the additive effects of natural and

unreported mortality, total mortality could be 35 to 50 percent higher than that

reported. Some bias may exist against reporting legally killed wolves with radio

collars; therefore, the actual unreported mortality from hunting or trapping may be

less than that suffered by radio-collared wolves. Nevertheless, reported mortality

may substantially underestimate total mortality.

The highest annual harvest of wolves in southeast Alaska is in GMU 2. To estimate

mortality we pooled sex and age classes and used a staggered-entry Kaplan Meir

survival rate estimation method (Pollock et al. 1989) with 2-week intervals. Total

mortality (natural, legal, and illegal harvest) in a sample of 19 radio-collared wolves

from autumn 1993 to spring 1994 was 61 percent (SE = 11 percent); mortality in a

sample of 13 radio-collared wolves from autumn 1994 to spring 1995 was 38 percent

(SE = 13 percent) (Person and Ingle 1995; Person, in prep.). Lower mortality in the

second year reflected a shift in trapping effort to the southern half of GMU 2, away

from the study area. From these estimates, the most probable average annual

mortality in the study area on Prince of Wales and Kosciusko Islands for June 1993

to June 1995 was 50 percent (SE = 13 percent, total sample for both years was 24

individual wolves).

1 Alaska Department of Fish and Game. Unpublished data.

On file with: Division of Wildlife Conservation, Douglas, AK

99824.

x

9



Table 1—Number of wolves per 1000 square kilometers (390 mi2

) reported

during fall and winter in various areas of North America where deer are the

primary prey

Location Years Wolves Source

Number

Northeast Minnesota 1970-71 42 Van Ballenberghe et al. 1975

Northeast Minnesota 1967-69 40 Nelson and Mech 1986a

North-central Minnesota 1980-86 39 Fuller 1989

East-central Ontario 1969 36 Pimlott et al. 1969

Central Ontario 1958-65 38 Pimlott et al. 1969

Southern Quebec 1980-84 28 Potvin 1988

Vancouver Island 1983 44 Hatter and Janz 1994

Vancouver Island 1976 70 Hebert et al. 1982

Prince of Wales Island 1994 39 Person, in prep.

Figure 4—Distribution of wolf numbers in southeast Alaska by game

management units (GMUs) as predicted by habitat capability for deer

(USDA Forest Service 1991).

13
The variance of this model can be approximated by the following equation:

(3)

assuming that s and b are not significantly correlated and are density independent

(see appendix 2 for the derivation of these models). The model also represents a

point estimate in time and assumes the wolf population is closed (a reasonable

assumption for Prince of Wales and Kosciusko Islands). Survival rate is the most

important factor influencing λ, with birth rates of secondary importance. Substituting

0.5 (SE = 0.13) for s and 0.52 (SE = 0.50) for b (see appendix 2 for how these

values were estimated), we estimated λ to be 0.69 (SE = 0.23). Comparing this

estimate with a simulated population with λ = 1 and SE = 0.23, the results are different (t = 16.3, df = 14, P < 0.001), thereby indicating that the population declined

between June 1993 and June 1995. We caution that because of the limitations of the

data, λ should be interpreted only with respect to the significance of the difference

from one and not as a precise estimate of the actual value. These results are consistent with observations made in the field by biologists and trappers who believe that

wolves on Prince of Wales and Kosciusko Islands were at a population peak during

winter 1992-93 and have declined since, owing primarily to trapping and hunting (in

GMU 2, 86, 105, 103, 85, and 99 wolves were reported killed during the 1991-92,

1992-93, 1993-94, 1994-95, and 1995-96 trapping seasons, respectively4). We

cannot extrapolate from these results to assess population trends for wolves outside

of GMU 2. Trapping records indicate that harvest intensity is probably greatest in

GMU 2, but wolf numbers could be increasing or remaining stationary in other areas

while declining in GMU 2.

Wolf-deer interactions—Much emphasis has been placed on the role of wolf

predation in limiting or regulating ungulate populations (Gasaway et al. 1983,

1992; Mech 1970; Messier 1994; Peterson and Page 1988; Theberge 1990; Van

Ballenberghe and Ballard 1994). The focus has been primarily on the effects of

predation on moose and caribou. Most authors have concluded that wolf predation

can limit moose and caribou populations under some circumstances, particularly

when multiple predators, multiple prey species, or severe weather are involved

(Gasaway et al. 1992, Van Ballenberghe and Ballard 1994).

Much less attention has been directed toward the quantitative analysis of predatorprey dynamics with respect to wolves and deer (Fuller 1989, Hatter and Janz 1994,

Lewis and Murray 1993), although much is known qualitatively about the effects of

wolf predation on deer (Fuller 1991; Hoskinson and Mech 1976; Nelson and Mech

1981, 1986b). In Minnesota, severe winter weather caused a decline in numbers of

white-tailed deer (Odocoileus virginianus) in some areas (Mech and Karns 1977).

Wolves delayed the recovery of these deer populations, but they did not cause the

original decline (Mech and Karns 1977). Van Ballenberghe and Hanley (1984) hypothesized that three things tend to increase the probability of wolves suppressing deer

populations in southeast Alaska: (1) periodic winters of deep snow that result in

increased killing, (2) the patchiness of winter habitat for deer that reduces the time

4 Alaska Department of Fish and Game. Unpublished data.

On file with: Division of Wildlife Conservation, Douglas, AK

99824.

Var Var Var () () () , λ = F ++ +

H

G I

K

J +

+

F

H

G I

K

J s

b b b S

b

12 4 1

2 41

2 2 2

14
wolves spend searching for prey, and (3) the availability of marine food resources

that buffer wolves from cyclic fluctuations in their terrestrial prey. Mech and Karns

(1977) report that in a declining deer herd, surviving deer inhabit overlapping edges

of wolf-pack territories and wolves tend not to hunt in these areas, or buffer zones, to

avoid potentially fatal encounters with their neighbors. Klein (1981) suggests that in

southeast Alaska, where the boundaries of many pack home ranges are shorelines,

the potential for wolves to reduce deer numbers is increased because there are

fewer buffer zones among territories.

In the early 1960s, four wolves were transplanted to Coronation Island in an experiment to observe the effects of wolf predation on Sitka black-tailed deer (Klein 1996).

The wolves reached a peak population of 13 after 4 years and apparently reduced

deer numbers dramatically. As their food supply dwindled, the wolves declined in

number. The last wolf on Coronation Island was shot in the late 1960s, ending the

experiment (Merriam et al. 1994), and the deer population has since rebounded.

Coronation Island is too small (78 square kilometers [30 mi2

]) and supports insufficient alternative prey to sustain wolves in the absence of deer. The experiment

suggests that islands in southeast Alaska comparable in size to Coronation Island

are unlikely to support wolves permanently unless they are near other land masses,

thus enabling wolves to periodically emigrate or immigrate. Further, deer density

probably was near carrying capacity when wolves were introduced (Klein 1996).

Consequently, the resiliency of the deer population to wolf predation (i.e., its ability

to offset mortality from predation by increasing reproduction) probably was limited

because of lower reproductive rates in deer resulting from the overbrowsed and

degraded condition of the habitat (Klein 1996). The results from Coronation Island

suggest that if wolves and deer are confined to small islands of habitat, then predatorprey disequilibria may result.

The stability of deer and wolf populations depends on several factors, including the

rate of predation by wolves, the number of deer killed by hunters and other predators,

and the ratio of deer to wolves. The most important determinants, however, are the

rate of growth of the deer population and the frequency of stochastic events such

as severe winters. These latter factors are related to habitat quantity and quality.

For example, as deer or other ungulate populations approach carrying capacity,

intraspecific competition for food will reduce successful reproduction and increase

chronic mortality (Caughley and Sinclair 1994; McCullough 1979, 1987) and thus

reduce the fraction of the deer population that can be exploited by wolves and other

predators without causing the prey population to decline. A predator-prey equilibrium

(McCullough 1979) may result, in which predation reduces deer density sufficiently

to stimulate greater reproduction in deer, thereby making more deer available to the

predators. The stability of such an equilibrium is contingent on the availability of

suitable habitat for deer, such that the deer population can maintain a rate of growth

sufficient to offset losses to predation. Stochastic events, such as severe winters or

reductions in the abundance and quality of suitable habitat, may perturb the conditions

of equilibria and result in widely fluctuating wolf and deer populations. By limiting

immigration and emigration of both deer and wolves, the insular conditions commonly

encountered in southeast Alaska increase the probability that population fluctuations

may end in local crashes of deer populations. The fluctuations exhibited by the

population trajectories of wolves and moose on Isle Royale, MI, certainly illustrate the

consequences of insularity with respect to a mammalian predator-prey community

(Peterson and Page 1988).

15
The recovery of deer populations depends on the reproductive potential of the survivors, immigration from other areas, and the numerical response of wolves and other

predators (including humans) to declining deer density. If alternative species of prey

exist so that wolf numbers do not decline sufficiently to permit deer to increase (or if

mortality of deer from hunting or other predators remains high), or if the reproductive

potential of the deer population is reduced because of habitat loss, then recovery of

deer populations after a crash could take a long time (Van Ballenberghe and Hanley

1984). For example, deer populations in GMU 3 (including Kuiu, Kupreanof, and

Mitkof Islands) crashed during the early 1970s as a result of a series of hard winters

(Olson 1979). In 1975, deer hunting in GMU 3 was halted completely and remained

closed throughout most of the GMU for 18 years. Today, deer are still at levels far

below carrying capacity over most of the GMU (Kirchhoff 1994). The persistently low

deer numbers illustrate that interactions of deer and their predators (in this instance,

wolves and black bears) may, under some circumstances, retard recovery of the deer

population. Although deer also declined in GMU 2 following the same hard winters,

snowfall on the more southern islands was not as heavy, and more of the landscape

in GMU 2 was sheltered by productive old-growth forest. In marked contrast to the

result in GMU 3, deer in GMU 2 did not decline as far and rebounded much more

quickly after the hard winters.

The rate at which wolves kill large mammals ranges widely given the availability,

size, and vulnerability of prey. Direct estimates of predation rates on Sitka blacktailed deer are not available. We therefore estimated predation rate by deriving a

series of equations incorporating average weights of deer, proportion consumed by

wolves, average weights of wolves, and their daily requirements for food intake. We

calculated the weight of edible meat from each deer carcass:

(4)

where

wcons = weight in kilograms of meat consumed per deer carcass,

wad = average weight in kilograms of adult deer,

= proportion of adult deer carcass consumed,

= proportion of adults in the deer population,

wf = average weight in kilograms of fawns,

= proportion of fawn carcass consumed, and

= proportion of fawns in the deer population.

Next we estimated the weight of deer meat consumed per wolf per year:

(5)

where

Cwolf = weight of deer meat in kilograms consumed per wolf per year,

wwolf = average weight in kilograms of wolves,

ww w cons ad ad ad f f f = + ( )( )( ) ( )( )( ) , φ ψ φψ

φad

ψad

φf

ψf

C wd wolf wolf wolf wolf = ( )( )( )( , Φ 365)

16
dwolf = daily per capita food requirement in kilograms of food per kilogram of wolf,

and

= proportion of deer in the diet.

Finally, an estimate of the number of deer killed per wolf per year (PR) was

calculated:

(6)

and its variance:

(7)

(for the parameter estimates used, see appendix 3). From inputting of parameter

values appropriate for wolves and Sitka black-tailed deer in southeast Alaska, we

estimated predation rate to be 26 deer per wolf per year (SE = 4.1). This calculation

assumed that wolves exhibit a type I functional response (Holling 1966) resulting in

the rate of predation remaining constant despite changes in the density of prey.

To evaluate the potential for equilibria between wolves and deer given our estimate

of predation rate, we used a model proposed by Keith (1983) that combines predation rate, rate of growth of the prey population, and the fraction of the recruitment

to the prey population removed by hunting or other predators to calculate the number

of ungulate prey per wolf (equilibrium ratio) necessary for equilibrium to occur:

(8)

where

N = number of deer per wolf necessary for equilibrium prior to parturition,

PR = number of deer killed per wolf per year,

= finite rate of increase of deer in the absence of predation measured prior to

parturition, and

H = fraction of annual recruitment to the deer population removed by hunting or

other predators.

Van Ballenberghe and Hanley (1984) used this model, or equilibrium function, to

explore the influence of changes in λ on equilibrium ratios brought about by habitat

changes. They concluded that reductions in λ dramatically increase the number of

deer per wolf needed for equilibrium and reduces the probability that stability between

deer and wolves will occur. Unfortunately, the equilibrium function (eq. 8) is deterministic and does not reflect the uncertainty associated with the input parameters.

We altered the model to correct for this attribute by replacing the input variables

with random samples drawn from the probability density function (pdf) of each

parameter as defined by their sampling distributions or some appropriate hypothetical distribution:

Φwolf

P C

w R

wolf

cons

= ,

Var Var Var ( ( ) () , P w C

w

C

w R cons

wolf

cons

wolf

cons

= −F

H

G I

K

J + F

H

G I

K 2 J

2 2

1

N P

H

H R = − − > <

λ

λ

1 1

1 1 b ga f, for and

λ

17
(9)

where

= vector of equilibrium solutions for the number of deer per wolf necessary

for equilibrium prior to parturition,

= vector of random samples from the pdf of PR with μ = a and σ = b,

= vector of random samples from the pdf of λ with μ = a and σ = b, and

= vector of random samples from the pdf of H with μ = a and σ = b.

The model assumes that predation by wolves and other predators is a source of

additive mortality, that λ encompasses all reproduction, immigration, emigration,

and compensatory mortality, and that each input parameter is an independent random variable. The variance of may be approximated by the following equation:

(10)

A Monte Carlo simulation was conducted to estimate the equilibrium ratio for deer

and wolves in GMU 2 using the following parameter estimates:

—Connolly’s (1981) review suggests finite rates of increase as high as 1.4 for

established populations of mule and black-tailed deer. For these model simulations,

we assumed a relatively high λ (μ = 1.3, SE = 0.05) because deer seem to be

well below carrying capacity in GMU 2, based on browse and pellet group surveys

(Kirchhoff 1993). About 95 percent of the values fell between 1.2 and 1.4.

—The analysis in this report suggests a predation rate of 26 deer per wolf per

year in areas where deer are the primary prey species (>75 percent of the diet).

Actual rates of killing attained will be higher or lower in any given year depending on

availability of alternate prey, fawn-to-adult ratios in the kill, and snow conditions that

make deer more or less vulnerable to wolves. Our estimate is higher than predation

rates reported for wolf predation on white-tailed deer (Fuller 1989) because Sitka

black-tailed deer are about 25 to 30 percent smaller. For these model simulations,

we estimated the standard error for predation rate to be 4.1. Thus, 95 percent of the

values fell between 18 and 34 deer per wolf per year.

N

P

H

R ab

ab ab

' , ,

'

,

'

,

' =

− −

a f

e je j af af λ 1 1

N'

PR ab,

'

a f

λ a b,

'

a f

H a b,

'

a f

N'

λ'

PR

'

Var Var Var

Var

N P

H

P

H

H P

H

R

R

R

' '

'

' a f e j b ga f b g b g a f

a f b ga f

= − −

L

N

M O

Q

P + − − −

L

N

M

M

O

Q

P

P

+ − −

L

N

M

M

O

Q

P

P

1

1 1 1 1

1 1

2

2

2

2

2

λ

λ

λ

λ

18
—We assumed that the only other significant predation on deer in GMU 2 was

from hunting. Although black bears do prey on fawns, the extent of this predation is

unknown and no estimate is possible. Consequently, equilibrium ratios predicted by

the simulation may underestimate the true values if bear predation is significant. In

our simulation, the value H refers to the proportion of the annual increment (population increase) of deer removed each year by hunting. To obtain this value, we estimated the current deer population on Prince of Wales Island from surveys of deer

pellet groups on winter range (productive old-growth forest below 450 meters [≈1,500

ft]) (Kirchhoff 1993, Kirchhoff and Pitcher 1988). From a standard conversion factor

(Kirchhoff 1990), mean pellet-group density was converted to an equivalent deer

density of 14.6 deer per square kilometer (38/mi2

; n = 11 watersheds). Assuming

deer winter range is approximately equal to productive forest land, the current population of deer on Prince of Wales Island may be close to 42,000 deer (14.6 deer per

square kilometer 2895 square kilometer of winter range). Because this population

estimate is lower than the habitat capability of 55,000 deer based on the USDA

Forest Service (1996) model, we assumed a high finite rate of increase in the population (1.3). With the population growing at this rate, the annual increment is 12,600

deer (0.3 42,000). The average deer harvest from 1993 to 1995 on Prince of

Wales Island was about 2,700 deer, which represented 21 percent of the annual

increment.5 In the model, we assumed the proportion of the annual increment

removed by hunting each year was 0.21 (SE = 0.05). The large standard error

(25 percent of the mean) reflects the uncertainty associated with this parameter

estimate. Population estimates based on pellet groups generally have low precision,

and the error associated with the habitat suitability model for deer is compounded

within its structural and functional components. In addition, hunting effort and success may differ widely owing to weather conditions.

The results of 10,000 simulations predicted a mean equilibrium ratio of 113 deer per

wolf (SE = 29) (fig. 5a). A cumulative frequency plot of the results (fig. 5b) shows that

there would be a 95-percent probability of equilibrium occurring if the ratio was 170

to 180 deer per wolf. Thus, if the objective is to maintain adequate prey to sustain

250 to 300 wolves on Prince of Wales and Kosciusko Islands (the current estimated

population) with a 95-percent chance of equilibrium and still support subsistence and

sport deer harvesting and current levels of wolf harvest, then sufficient habitat for

42,500 to 54,000 deer is needed. For comparative purposes, the habitat suitability

model for deer (USDA Forest Service 1996) predicts the current habitat capability of

Prince of Wales and Kosciusko Islands (on Federal lands) to be about 55,000 deer

(margin of error unknown).

We caution that equilibrium does not necessarily imply stability, which is a measure

of the tendency for a system to return to a condition of equilibrium after being perturbed (May 1974). Nonetheless, a large equilibrium ratio, particularly for wolves and

deer confined to small geographic or habitat islands, would suggest a low probability

of stability between predator and prey. The potential for equilibrium, and consequently

stability, is diminished if habitat loss causes residual deer populations to exist at a

5 Alaska Department of Fish and Game. Unpublished data.

On file with: Division of Wildlife Conservation, Douglas, AK

99824.

H'

×

×

19
lower density that is also closer to carrying capacity. Increased intraspecific competition for food within the remaining deer habitat will likely lower reproduction. For

example, if λ were reduced to 1.15 and all other parameters remained the same,

then the mean equilibrium ratio predicted by equation (9) is 219 deer per wolf

(SE = 82). Over 380 deer per wolf would be needed for a 95-percent probability

of equilibrium. The implication of this example is that equilibrium, and therefore

stability, would be difficult to achieve and tenuous at best if carrying-capacity for

deer declines.

Wolf Conservation Our review raises a number of questions about the long-term viability and distribution

of wolves in southeast Alaska. The Alexander Archipelago wolf exists in limited

numbers in an insular environment undergoing rapid change. Issues focus on three

general areas: (1) a decline in carrying capacity for deer; (2) the effect of road use by

humans on mortality and displacement of wolves; and (3) continued exploitation of

wolves. These changes are related to past and planned timber harvesting on Federal

and private lands.

Figure 5—(A) Frequency plot of the number of deer per wolf

(equilibrium ratio) predicted by Monte Carlo simulation of the

equilibrium function. (B) Cumulative probability plot showing the

number of deer per wolf needed for 80- and 95-percent probability

of equilibrium.

A

B

20
Prey Populations Deer carrying capacity—Maintaining viable, well-distributed wolf populations ultimately will depend on maintaining habitat to support a relatively abundant, welldistributed, and stable population of deer. Short-rotation clearcut logging of oldgrowth forests in southeast Alaska will reduce habitat capability for Sitka blacktailed deer (USDA Forest Service 1991, 1996). This conclusion is supported by an

extensive body of research spanning 30 years on forest succession following logging

(Alaback 1982, Alaback and Herman 1988, Alaback and Juday 1989), silvicultural

practices (Alaback and Tappeiner 1984, DellaSala et al. 1994, Doerr and Sandburg

1986, Nyberg et al. 1989), deer habitat relations (Bloom 1978, Kirchhoff and Schoen

1987, Klein 1964, Klein and Olson 1960, Schoen and Kirchhoff 1985, Schoen et al.

1988, Van Ballenberghe and Hanley 1984, Wallmo and Schoen 1980, Yeo and Peek

1992), and nutritional ecology of deer (Hanley 1984, 1987; Hanley and McKendrick

1985; Hanley et al. 1987, 1989; McArthur et al. 1993; Parker et al. 1993) in southeast

Alaska. Short-rotation clearcut logging replaces productive old-growth forest, which is

important deer winter habitat, with even-aged, second-growth stands of much lower

habitat value for deer (Wallmo and Schoen 1980). Although young clearcuts may

temporarily produce abundant forage, typically it is of poorer nutritional quality than

forage available in old-growth forest stands (Hanley et al. 1989), and some understory plant species may never reappear on sites under short-rotation, even-aged

management (Alaback 1982). Moreover, what forage is present is not available to

deer during periods of deep snow.

Within 30 years of clearcutting, regenerating conifers shade out most understory

vegetation (Alaback 1982), creating poor habitat conditions for deer (Wallmo and

Schoen 1980). These stands represent a serious problem for deer because the

habitat is poor in all seasons, and these conditions persist for a long time (150 to

200 years) (Alaback 1982, Wallmo and Schoen 1980). Although precommercial

thinning may delay crown closure in second-growth stands, the improvements in

their value as winter habitat for deer are modest and short-lived (<20 years) (Alaback

and Tappeiner 1984).

Old-growth forest stands composed of relatively tall, large-canopied trees are particularly important to deer during severe winters. High-volume old growth intercepts

snow more effectively than low-volume old growth (Kirchhoff and Schoen 1987) and

receives disproportionately high use by deer during periods of deep snow (Schoen

and Kirchhoff 1990). Under the current Forest plan (USDA Forest Service 1996, alt.

9), about 61 percent of the original productive old growth on Federal lands in GMU 2

will be cut within the next 100 years. About 15 to 20 percent of the land in GMU 2

is owned by Native corporations under the provisions of the Alaska Native Claims

Settlement Act of 1971 (ANSCA). Between 65 and 81 percent of the original productive old growth on Native lands in GMU 2 will likely be cut within the next 20 years

(USDA Forest Service 1991). Logging on both Federal and Native lands in GMU 2

will likely result in the conversion to young-growth forest of 75 to 80 percent of the

original productive old-growth forest within 100 years. Timber harvesting on Federal

and Native-owned lands in GMU 3 will remove about 48 to 50 percent of the original

productive old-growth forest and, in combination with logging in GMU 2, will potentially

affect over 65 percent of the wolf population in southeast Alaska (fig. 4).

21
This loss of habitat will likely reduce deer populations, and consequently affect deerwolf dynamics. As our simulations have shown, habitat changes that lower reproductive rates in deer will reduce the probability of equilibria between wolves and deer

and increase the sensitivity of equilibria to perturbation. In planning timber harvests,

efforts to minimize the loss of long-term deer carrying-capacity at geographic scales

consistent with the size of wolf pack home ranges, would likely reduce the probability

of disequilibria between wolves and deer.

Forest fragmentation—In southeast Alaska, forests are a mosaic of high-, moderate-, and low-volume stands interspersed with open muskegs and alpine terrain.

This natural fragmentation is intensified when clearcut logging converts individual

forest stands into a patchwork of smaller old-growth stands isolated by clearcuts.

During periods of deep snow, deer confined to isolated stands of old-growth forest

consume the available food resources and suffer higher rates of mortality from malnutrition than deer in unfragmented old-growth forest (Kirchhoff 1994). If wolves also

are present, then forest fragmentation may focus wolf predation on specific sites

where deer are concentrated and relatively vulnerable (Hebert et al. 1982, Janz

1989, Nelson and Mech 1986b). For example, logging roads in southeast Alaska are

typically constructed along the coastline or valley bottoms, with clearcuts spaced out

along the roads on the lower hillsides. Residual patches of old-growth forest among

clearcuts are connected by these roads, which are occasionally traveled by wolf

packs. Deer concentrate in these patches during winter when snow depths prevent

them from using open areas, and may suffer higher mortality from wolf predation.

From Vancouver Island, British Columbia, McNay and Voller (1995) report the

efficiency of predation by wolves to be high in fragmented, heavily logged landscapes. They calculated the annual survival rate for adult resident deer at low

elevations to be 73 percent and concluded this level, if continuous, is inadequate

to sustain the deer population. In contrast, migratory deer, which made greater use

of high-elevation habitats and completely avoided low-elevation second-growth

forests in winter, were able to avoid predation and consequently had high rates

of survival (95 percent). McNay and Voller (1995: 145) cautioned that:

...Retention of older, intact forests is basic to rebuilding deer populations. Forest harvesting, hence, road building and spatial isolation of winter habitats, may intensify

predation on 1 segment of the deer population (resident deer) and indirectly impede

recruitment to the other segment (migratory deer). The result likely contributes to

declines in deer populations and an overall loss of population resiliency.

Avoiding further habitat fragmentation, especially at lower elevations and in the beach

fringes where wolves commonly prey on deer in winter, should enhance the likelihood

of maintaining deer populations in southeast Alaska. Alternative methods of timber

harvest, such as single-tree selection could minimize the effects of logging, especially

in areas of critical habitat for deer.

Roads Studies in Wisconsin, Michigan, Ontario, and Minnesota indicate a strong relation

between road density and the presence or absence of wolves (Fuller 1989, Jensen

et al. 1986, Mech et al. 1988, Thiel 1985). These studies show that wolves generally

failed to survive in areas with road densities >0.6 kilometer per square kilometer

(0.9 mi/mi2

) whereas they persist in similar areas with lower densities of roads. Mech

(1989) speculated that excessive mortality experienced by wolves in roaded areas is

compensated for by individuals that disperse from adjacent roadless areas. Citing the

expansion of wolf populations in Minnesota, Wisconsin, and Michigan, Mech (1995)

suggested that road density is not really a deterrent, provided human populations

22
are tolerant of the presence of the wolves. Nevertheless, in an analysis of habitat

selection by colonizing wolves, Mladenoff et al. (1995) report that roadless areas

are preferred, and occupation of roaded landscapes occurs after roadless areas are

saturated. In all the circumstances described in which wolves successfully inhabited

roaded or developed areas, adjacent roadless areas were present.

There are several plausible explanations for the absence of wolves in densely roaded

areas. In some instances, wolves may avoid roaded areas depending on the type of

use the roads receive (Thurber et al. 1994). In most instances, their absence may be

a direct result of mortality associated with roads (Berg and Kuehn 1982, Mech 1977,

Van Ballenberghe et al. 1975). Substantial human-caused mortality can occur even

when wolves are completely protected from legal hunting and trapping (Fritts and

Mech 1981, Fuller 1989). Fuller (1989) reported that 80 percent of the identified

mortality in a protected study area in Minnesota was human caused. Similarly, Mech

(1989) noted that 60 percent of the mortality in a roaded study area was human

caused, whereas no mortality was human caused in an adjacent roadless area.

Over the past 40 years, timber harvest has been most extensive in GMUs 2 and 3.

Road densities in 50 percent of the Wildlife Analysis Areas (WAA) in GMU 2 and

17 percent of the Wildlife Analysis Areas in GMU 3 currently exceed 0.6-kilometerper-square kilometer (USDA Forest Service 1996, Tongass land management plan

geographic database), a density suggested to be inimical to wolves in other areas.

The current Forest plan for the Tongass National Forest calls for road densities 3 to

4 times higher than exist today in GMUs 1A, 2, and 3 (fig. 6). Although wolves on

Prince of Wales Island currently use areas with road densities greater than 0.6

kilometer per square kilometer (0.9 mi/mi2

), their “core areas” are generally located in

the least densely roaded portion of the home range, and the wolf activity that does

occur in densely roaded areas occurs primarily at night (Person, in prep.).

Figure 6—Kilometers of existing road and projections of

future kilometers of road to 2090 for GMUs 1A, 1B, 2, and

3 (USDA Forest Service 1991). The GMUs encompass

most of the range of wolves in southeast Alaska. The data

do not include roads on state, private, or Native lands.

23
Based on harvest statistics from 1990 to 1995 in GMUs 2 and 3 and tabulated by

WAA, wolves experienced significantly higher mortality from hunting and trapping

in WAAs with higher road densities (r = 0.59, P < 0.001, n = 56). We calculated road

density by using the area within a WAA below 370 meters (≈1,200 feet) elevation

as the denominator. Wolves spend most of their time at low elevations (Person,

in prep.), and calculations of road density should reflect this relation. Analysis of

variance indicated a significant effect of road density on the 6-year average wolf

harvest (P < 0.002, df = 49) reported for WAAs in GMUs 2 and 3 after controlling for

the size of WAAs (a square root transformation of wolf harvest was used to stabilize

the variance). Harvest rates increased sharply in WAAs exceeding 0.3 kilometer of

road per square kilometer (0.49 mi/mi2

) (fig. 7a and 7b). Indeed, in two areas on

Prince of Wales Island (Kasaan Peninsula and Big Salt Lake), trappers and hunters

eliminated all known resident wolves (Person, in prep.). In both areas, road density

exceeded 0.6 kilometer per square kilometer. Moreover, two female wolves with radio

collars, each paired with a male, dispersed into the vacant areas and attempted to

establish packs. Both wolves were killed (one legally, one illegally) by hunters within

18 months.

We regressed the 6-year (1990-95) average wolf harvest from WAAs in GMUs 2

and 3 against the linear kilometers of road within a WAA. To stabilize the variance,

we used a square-root transformation of the harvest data for wolves. We used linear

distance of road rather than road density, because most roads are along valley

bottoms and through forest stands that are the most productive for timber and deer.

Overall road density in a WAA may be low, but the roads that do exist are likely to

go through or be located adjacent to areas used heavily by wolves.

Figure 7—(A) Mean numbers of

wolves killed per Wildlife Analysis

Area (WAA) during the regular

trapping and hunting seasons by

the density of roads contained

within a WAA after controlling for

the size of the WAA. Harvest

numbers represent the 6-year

average harvest from 1990 to

1995. The filled circles represent

the mean and the bars represent

the 95-percent confidence intervals.

(B) Plot showing the mean number

of wolves killed per Wildlife Analysis

Area (WAA) during the regular trapping and hunting seasons by the

density of roads contained within a

WAA after controlling for the size

of the WAA. Harvest numbers

represent the square root of the

6-year average harvest from 1990

to 1995 to stabilize the variance.

The filled circles represent the

mean and the bars represent the

95-percent confidence intervals.

A

B

24
Regression analysis indicated a significant positive relation between kilometers of

road and wolf harvest (r

2 = 0.33 , df = 55, P < 0. 001) (fig. 8). The model predicted

that wolf mortality due to hunting and trapping increased twofold when the linear

distance of road exceeded 95 kilometers (59 mi), threefold when it exceeded 171

kilometers (106 miles), and fourfold when more than 234 kilometers (145 mi) of road

existed within a WAA. The average area below 370 meters (≈1200 ft) in elevation for

WAAs in GMUs 2 and 3 is 233 square kilometers; (89 mi2

); therefore, the distance

values correspond to densities of road equivalent to 0.41, 0.73, and 1.0 kilometer

per square kilometer, respectively (0.66, 1.19, and 1.63 mi/mi2

). We caution that

the model explains only 33 percent of the variation in the data, and the hyperbolic

prediction intervals around the regression lines are large; therefore, considerable

deviation from predicted values is likely to be observed.

Means by which wolf mortality associated with roads can be better controlled would

benefit from further investigation and consideration. This approach would include

evaluating management of road use. For example, infrared traffic sensors and direct

observations revealed that several roads posted as closed to motorized traffic on

Prince of Wales Island were frequently driven over, and in two cases, gates were

Figure 8—Plots showing regressions of the square root of the

6-year average wolf kill from 1990

to 1995 for GMUs 2, 3, and 2 and

3 combined versus the linear

kilometers of road within a Wildlife

Analysis Area (WAA).

25
repeatedly vandalized in 1994 and 1995 to enable motorized access.6 Further, the

construction of gates or the removal of culverts may not be sufficient to eliminate

all-terrain vehicle and snowmobile traffic.

Exploitation Exploitation refers to the deliberate killing of wolves by people, either by trapping

(and snaring) or shooting. For discussion purposes we divide the wolf kill into two

categories, legal and illegal harvest. The legal harvest by hunters and trappers

accounts for most of the annual take, and is typically managed by adjusting season

lengths, harvest limits, or restrictions on methods of take. Illegal harvest includes

wolves that are killed but are either not salvaged or otherwise not presented to

ADFG for sealing of the pelts (as required by regulation). Illegal harvest is difficult

to estimate, monitor, and control.

Legal and illegal exploitation of wolves will almost certainly increase as human populations increase, and as expanded access to the interior of islands brings people and

wolves into more frequent contact. Furthermore, as human populations increase and

the demand grows for a deer population that, under current habitat management, is

simultaneously declining, wolves will inevitably be viewed by some as undesirable

competitors. These trends in human population, access, and rates of exploitation

are particularly evident on Prince of Wales Island. As recently as 1960, the human

population on Prince of Wales Island numbered slightly more than 1,000 people.

Air and ferry service were limited, and only a few kilometers of road existed outside

a handful of small communities. Currently the population on the island and in the

immediate area has grown to over 7,000 people (U.S. Department of Commerce

1996). The population has increased 13 percent since the 1990 census (U.S. Department of Commerce 1996). Since 1954, about 4,800 kilometers (3,000 miles) of road

have been built on private and Federal lands on Prince of Wales Island.7 8 These

roads, originally built for access to timber, now provide a transportation network

among communities and provide people with ready access to many otherwise inaccessible areas of the island. This rapid rate of development is expected to continue. For the Ketchikan Area (GMUs 1A and 2), the kilometers of existing road will

double in 30 years; the Stikine Area (GMUs 1B and 3) likely will have twice as many

roads in 20 years (USDA Forest Service 1991).

Even though most of the wolves harvested in southeast Alaska are taken along the

shore from boats (55 percent), a large and growing percentage are now taken from

the road system (44 percent).9 Roads on Prince of Wales Island access 19 of 22

Wildlife Analysis Areas, representing 78 percent of the land area in GMU 2. Except

for the Thorne River area, all WAAs on the Island are accessible by skiff. Due to the

relative ease of access and the continued efforts of trappers, wolves on Prince of

Wales Island are heavily exploited. Total annual mortality on the island may exceed

45 percent (Person and Ingle 1995) in some years.

6 Person, D.K. Unpublished data. On file with the author.

7 USDA Forest Service. GIS database. Tongass National

Forest, Regional Office, Juneau, AK 99801.

8 Alaska Department of Fish and Game. Internal report.

9 Feb. 1995. On file with: Habitat Division, Ketchikan,

AK 99901.

9 Alaska Department of Fish and Game. Unpublished data.

On file with: Division of Widlife Conservation, Douglas, AK 99824.

26
Although trapping effort will undoubtedly diminish if wolf populations decline and

animals become harder to catch, the relative ease of access and liberal hunting and

trapping seasons may still result in harvest that is unsustainable. Deer populations

currently may be sufficiently high to enable wolf numbers to rebound after several

years of intensive trapping and hunting pressure. Nonetheless, if deer carrying

capacity continues to decline in the future, then the resiliency of wolf populations

likely will diminish, compounding the effects of overharvesting wolves by delaying

or reducing the potential for their population recovery. In areas experiencing heavy

mortality, regulatory changes may be needed to bring total wolf mortality within

sustainable limits. Based on our analysis of birth rates and population size for wolves

on Prince of Wales and Kosciusko Islands, we estimate the per capita birth rate for

wolves to be approximately 0.33 (SE = 0.15). The buffering effects of immigration

and emigration are probably limited for most of the wolves in southeast Alaska;

consequently, total annual mortality should not exceed reproduction to maintain

current population levels. Thus, to maintain current population levels, a level of

mortality (from all causes; including natural, legal, and illegal harvest) for wolves

in southeast Alaska is likely to be less than or equal to 30 to 35 percent.

Conclusions Wolves, deer, and humans have coexisted in southeast Alaska for centuries and

perhaps thousands of years. The natural environment of the past succeeded in

supporting species that are of concern in the managed environment of the present.

Given the overwhelming complexity of ecological systems and the state of scientific

knowledge about them, we use the past as our default position, against which future

management plans are compared. We suggest that the following questions be considered in making management decisions that may effect wolves and their habitat.

Can long-term deer carrying capacity be maintained at levels similar to current

conditions after logging, particularly if clearcut logging is continued on a large

scale?

This is the most important consideration for the long term. Results from research

on postharvesting treatments of clearcut stands, such as precommercial thinning,

suggest that benefits to deer from thinning are short-lived. The current state of

knowledge offers no likely solutions to the problem of maintaining long-term deer

carrying capacity while using extensive short-rotation clearcut logging. Other timber

harvesting strategies, such as limited selection harvests, may ameliorate some of

the impacts of logging on deer carrying capacity, but the effect of these alternative

harvesting methods on deer is unknown at present.

If carrying capacity is reduced, then what is the minimum carrying capacity for

deer that will support a viable and well-distributed population of wolves?

We cannot suggest a minimum deer population because we do not know what would

constitute a minimum viable wolf population either demographically or genetically.

Many more data are needed concerning the population structure, genetic structure,

and predator-prey relations of wolves in southeast Alaska before this question can

be answered. This question also must be addressed separately for the major island

groups and possibly for individual sections of the mainland that are divided by major

glaciers or river drainages. Our analyses suggest that sustaining the estimated current population of 250 to 300 wolves on Prince of Wales Island would require at least

27
42,500 to 54,000 deer (6 to 8 deer per square kilometer [16 to 21 deer/mi2

]) for a

95-percent probability of equilibrium. As deer carrying capacity declines in the years

after extensive timber harvest, we would expect both deer numbers and reproductive

rates to decline as well. In this situation, a disequilibria between wolves and deer

likely would occur. Whether new equilibria would result is not known, but even if

they do, they probably would be more difficult to achieve and less stable. At lower

equilibria, there may be insufficient deer numbers to support current subsistence

and sport deer harvest levels.

If roads are built, can access be managed effectively to reduce wolf mortality?

Effective management of roads to control human access should help to reduce wolf

mortality; however, closing roads has not been fully successful because of practical

difficulties and opposition voiced by residents within the communities affected by road

closures. The demands of a growing human population for access to the Tongass

National Forest for commercial and recreational purposes likely will make management of access even more difficult, while doing so will perhaps be even more important. A systematic access management approach that considers the biological requirements of wolves would be beneficial. For example, not building roads, or closing

existing ones, in core activity areas or near denning sites would be beneficial. Of

course, this type of action would require reliable information concerning the movements and activities of wolves in areas where access management is proposed.

Considerable time and expense would be necessary to collect such information.

Can wolf mortality from trapping and hunting be controlled by regulatory

changes?

Regulatory changes could have a marked effect on wolf mortality, nevertheless, the

effect may be limited by the logistical difficulties of enforcing regulations in an area

the size of the Tongass National Forest. Moreover, in areas where a large portion

of the human population is employed in industrial or agricultural occupations, the

number of wildlife law violations may be high (Berger and Daneke 1988). Educational

programs concerning wolves, such as those available in Minnesota (International

Wolf Center, Ely, MN), where a generation of people have grown up while wolves

have been protected, might help the public understand the need to comply with

regulatory changes in southeast Alaska and thus help to assure the effectiveness

of regulations in managing human-caused mortality of wolves.

***

Although this report presents a substantial body of scientific information concerning

wolves in southeast Alaska, the data are temporally and geographically limited in

scope and caution must be used when drawing long-term, forest-wide conclusions

from them. Nevertheless, we believe that continued extensive timber harvesting,

especially short-rotation clearcut logging, will have adverse consequences for wolves

and place some population segments at risk (particularly those wolves in GMU 2 and

perhaps those in GMU 3).

28
In our opinion, the long-term consequences of continued short-rotation, clearcut timber harvesting and the short-term consequences of road access and legal or illegal

wolf harvest result in increased risk to wolf viability. The Alexander Archipelago wolf

exists as a population, perhaps less than 1,000 animals, that is potentially divided

into smaller subgroups associated with different portions of the mainland and island

clusters. Our analysis suggests that the largest portion of the population inhabits

areas where extensive timber harvest has occurred or is planned. Maintaining a

minimum average density of deer equal to 5 deer per square kilometer (13 deer/mi2

)

in wildlife analysis areas that currently support deer numbers greater than or equal

to 5 deer per square kilometer and where deer are the principal species of prey for

wolves would reduce long-term risk to wolf viability. This density of deer is likely to

support wolves and sustain the current subsistence harvest of deer by humans. In

other wildlife analysis areas where deer are the primary prey, but current densities

of deer are lower than 5 deer per square kilometer, maintaining deer numbers would

reduce long-term risk to wolf viability.

In addition, in biogeographic provinces where extensive timber harvesting has occurred or where extensive harvesting is planned (see USDA Forest Service 1996 for

description of biogeographic provinces), maintaining large, unfragmented, and unroaded blocks of habitat within each biogeographic province where wolves occur

would reduce long-term risk to wolf viability. Making each “reserve” large enough to

encompass the core activity areas of at least one wolf pack markedly increases the

likelihood of their effectiveness. Core areas are often disjunct and the utilization

distributions are frequently multimodal (Person, in prep.). Analysis of radio-telemetry

data from wolves on Prince of Wales and Kosciusko Islands suggests that the

75-percent confidence ellipse (Jennrich and Turner 1969) or the 85-percent adaptive

kernel home range (Worton 1989) would be adequate to delimit an area that completely overlaps core areas regardless of the shape of the utilization distribution

(fig. 9). Both home range models indicate that risk to wolves increases if reserves

are less than 200 square kilometers (78 mi2

) in size. An average density of 7 deer

per square kilometer (18 deer/mi2

) has a high probability of sustaining 7 to 11 wolves

(depending on the density of deer in the matrix that is overlapped by the wolf pack

home range) of which 2 to 4 would likely disperse from the reserve annually. Given

the high mortality rate for dispersers, we expect that at least one dispersing wolf

would survive for more than one year and be available to replace wolves eliminated

from the matrix.

Establishing at least one reserve per 800 square kilometers (≈300 mi2

) of area

within each biogeographic province where wolves occur would meet the above

need. The spacing of reserves is unlikely to be critical because wolves probably

are highly mobile within provinces. The equilibrium model would predict that the

proposed density of reserves would have a high probability of supporting about

30 wolves per 1000 square kilometers if the matrix of land between reserves can

support a minimum of 5 deer per square kilometer.10 Although the matrix of land

10 This density was computed as follows: no. of wolves

supported by reserves + no. of wolves supported by matrix

= ([200 × 7]/180)+[600 × 5]/80) = 24 wolves/800 square

kilometers = 30 wolves/1000 square kilometers.

29
between reserves should be capable of sustaining wolves, the expectation is that

the density of wolves in the matrix would be lower than in the reserves and individual packs may periodically disappear from these lands due to hunting and trapping (legal or illegal). The matrix of developed lands would presumably function

as a wolf population sink siphoning off dispersers from the reserves, and thus

increase the probability of stability between wolf and deer populations within the

reserves. The matrix also would enable wolves to travel among reserves.

The objective of the reserves is to retain enough high-quality habitat with limited

human access to assure that some packs persist as source populations for those

wolves affected by extensive development. If the strategy described above was

applied to Prince of Wales and Kosciusko Islands, then nine reserves would be

Figure 9—Radio locations for three wolf packs on central Prince of Wales Island, March

1993 to September 1995. The radio locations clearly indicate areas where activity is

concentrated and illustrate the disjunct nature of the usage distributions. The area represented by the average of the 75-percent bivariate-normal confidence ellipse home ranges

(shown) and the 85-percent adaptive kernel home ranges for all wolf packs monitored on

Prince of Wales and Kosciusko Islands is suggested as the minimum size of reserves

that will encompass the core activity areas of at least one wolf pack.

30
created totaling about 180 000 hectares (437,000 acres). If timber harvest was

limited and road construction prohibited in the reserves, consistent with reserve

objectives, then risk to long-term wolf viability would be reduced. We predict that a

total of 100 to 200 wolves would be sustained on Prince of Wales and Kosciusko

Islands depending on the capability of the matrix to support deer over the long

term and the intensity of human-caused mortality of wolves in the matrix.

We emphasize that this strategy is appropriate only for biogeographic provinces that

currently support (or have the potential to support) dense populations of deer, such

as those provinces within GMUs 2 and 3. Data are lacking concerning home ranges,

movements, activity, and food habits of wolves inhabiting areas that can support only

low densities of prey. Attempting to maintain the density of current prey populations

and minimizing road construction would benefit wolf populations in these areas. More

detailed and precise information should result from further research.

Acknowledgments We thank the University of Alaska Fairbanks, USDA Forest Service, U.S. Fish and

Wildlife Service, National Biological Service, and Alaska Department of Fish and

Game for support and assistance in completing this paper; and the Northwest Scientific Association for assistance with manuscript review. M. Kirchhoff was supported

by Federal Aid in Wildlife Restoration Study 2.11 while working on this assessment.

We also thank L. Beier, R.T. Bowyer, M. Brown, C. Crocker-Bedford, E. Debevec,

B. Dinneford, M. Ingle, M. Hicks, D. Kellyhouse, R. Lande, D. Larsen, M. McNay,

B. Noon, R. Nowak, J. Schoen, C. Schwartz, W. Smith, and K. Taylor for their insight and editorial comments. We are grateful to the anonymous reviewers who

offered critical comments and helped to strengthen this report.

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38
Appendix 1 The model used to estimate the wolf population on Prince of Wales and Kosciusko

Islands was as follows:

(11)

where

Wpop = total wolf population,

A = area in square kilometers,

HR = average home range in square kilometers,

= proportion of home range overlapping neighboring wolf home ranges,

Wpack = average number of wolves per pack, and

= proportion of dispersers in wolf population.

Parameter estimates used in the Monte Carlo simulation of the model were as follows:

1. Pack territories were calculated from empirical data (mean = 280 square

kilometers [109 mi2

], SE = 78).a

2. Percentage of overlap among territories was calculated to approximate exclusive

use areas by a single pack (mean = 0.04, SE = 0.01).

3. Pack sizes were estimated from aerial observations (mean = 9.0, SE = 2.6 in fall

1994; mean = 5.6, SD = 3.0 in spring 1995).b

4. Percentage of dispersers was determined from empirical data (mean = 0.29,

SE = 0.09).

5. Land area of Prince of Wales and Kosciusko Islands is 6,808 square kilometers

(2,654 mi2

).

The variance of the estimate is approximated by the following equation derived from

the “delta” method (Seber 1983):

(12)

The equation assumes that all variables are independent random samples with

mean = μ and variance = . Ten thousand simulations were conducted, each

incorporating a random permutation of the input parameters.

a The home range estimate is an average of MCP and

95-percent adaptive kernel home ranges.

b Pack size estimates include data from packs not

containing radio-collared pack members.

W A

H

W

pop

R

pack = − • a f 1 α b g 1− β ,

α

β

α2

Var Var Var

Var Var

W H

AW

H

AW

H

W A

H

AW

H

pop R

pack

R

pack

R

pack

R

pack

R

d i b g b ga f a f b ga f

d i b ga f b g b ga f

= − −

L

N

M

M

O

Q

P

P

+ − −

L

N

M O

Q

P

+ − −

L

N

M O

Q

P + − −

L

N

M O

Q

P

2

2 2

2 2

1 1 1 1

1 1 11

β α

α

β α

β α β β α

39
Appendix 2 The Lotka-Leslie model used in this paper was derived in the following way. The

formal model is expressed as:

(13)

where

lx = survivorship to age class x,

bx = number of female offspring per female of age x, and

= finite rate of increase assuming a stable-age distribution.

Recalling that lx = (sx-1)(sx-2)(sx-3)...,

where

sx = annual survival rate for age class x,

the model can be rewritten as a function of survival rates:

We assume that b and s for age classes >2 are constant. For wolves, b0 = b1 = 0,

and b2 represents the birth rate at age of first breeding, which is likely to be lower

than the birth rate of older adults (b). Therefore the equation can be simplified as:

We then may solve for :

(14)

If we assume that s0 = s1 = s and b = b2 then the equation simplifies to:

(15)

The estimate of variance is obtained by the “delta” method described by Seber

(1983):

which yields the following variance estimator:

(16)

l l bx x

x

x

=

=

∞

∑ λ 0

λ

1

1

1

0 0 1 01 2

2

0 1

3

0 1

2

4 =+ + + + + b g b s b ss b bg bg sssba f sss

λ λ λλ K.

1 1 01 2

2

0 1

3

2

2 = + ++ + F

H

G I

K

J

ss bb g af s ssb s s

λ λ λ λ K .

λ

0 3 2 =− − − − λλ λ s s sb s ssb b 012 01 2 b g .

λ =

s s sb + + 2 2 1 24

2

e j .

Var Var Var λ ∂λ

∂

∂λ

∂ b g = af af F

H

G I

K

J + F

H

G I

K s J

s

b

b

2 2

,

Var Var Var b g λ = a f a f F ++ +

H

G I

K

J +

+

F

H

G I

K

J s

b b b S

b

12 4 1

2 41

2 2 2

.

40
Survival rates were estimated from the survivorship of radio-collared wolves. The

birth rate was estimated by the following formula:

(17)

where

fp = average number of female pups per pack (mean = 1.8, SE = 0.9),

= proportion of female dispersers in the female population (mean = 0.33,

SE = (0.12), and

fad = average number of females per pack in spring (mean = 2.3, SE = 1.9).

The variance of the estimate was approximated by:

(18)

b

f

f

p

ad

= b g 1− δ ,

δ

Var Var Var Var b f

f

f

f

f

f

f p

ad

ad

p

ad

p

ad

a f d i b g b g = b g F −

H

G I

K

J + F −

H

G I

K

J + −F

H

G I

K

J 1 1

2

2 2

δ δ

δ .

41
Appendix 3 The wolf predation rate on Sitka black-tailed deer in southeast Alaska was calculated

in the following way:

In southeast Alaska, adult bucks average 54.4 kilograms (120 lb; Merriam et al.

1994) and adult does average 42.2 kilograms (93 lb; Johnson 1987). Assuming a

60:40 female-to-male sex ratio in the adult population (due to buck-only hunting

and higher natural mortality in males), the average adult deer weighs about 47 kilograms (104 lb; 42.2 kilograms × 0.6 plus 54.4 kilograms × 0.4). Winter fawns (<1 yr)

average 19.5 kilograms (43 pounds; Johnson 1987). Predation rates on fawns versus adults are highly variable in the literature, and the factors affecting that ratio are

poorly understood (Fuller 1989). We conservatively assumed that an average of one

in three deer killed is a fawn (33 percent). About 74 percent of adult deer carcasses

are consumed (Ballard et al. 1987, Fuller 1989) and 88 percent of fawn carcasses

(Floyd et al. 1978). Thus, the average edible weight of each deer carcass is 29.1 kilograms or 64 pounds ([104 × 0.66 × 0.74]+[43 × 0.33 × 0.88]).

In other parts of North America where deer are the primary prey, the mean consumption rate of wolves is 0.04 kilogram of food per kilogram of wolf body weight

(0.09 lb of food per pound of wolf body weight) per day (range 0.06 to 0.10; Fuller

1989). An average wolf on Prince of Wales Island weighs 30.4 kilograms (67 lb;

n=26; Person, in prep.); thus, each wolf consumes 2.72 kilograms (6.0 lb) per wolf per

day (0.09 × 67). Given that requirement, and assuming a diet composed 77 percent

of deer, each wolf kills about 26 deer per year [(365 × 2.72 × 0.77)/29.1)].

42
Person, David K.; Kirchhoff, Matthew; Van Ballenberghe, Victor; Iverson,

George C.; Grossman, Edward. 1996. The Alexander Archipelago wolf: a

conservation assessment. Gen. Tech. Rep. PNW-GTR-384. Portland, OR:

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

Station. 42 p. (Shaw, Charles G., III, tech. coord.; Conservation and resource

assessments for the Tongass land management plan revision).

We summarized the scientific information available for the Alexander Archipelago wolf

(Canis lupus ligoni) in the Tongass National Forest of southeast Alaska. Information concerning the morphology, distribution, taxonomy, genetics, and ecology

of wolves are presented. Three issues for the conservation of wolves in southeast

Alaska are discussed: loss of long-term carrying capacity for deer due primarily to

extensive timber harvesting, increased mortality of wolves associated with improved

human access from roads, and continued high levels of harvest of wolves by humans.

Continued timber harvesting at current levels and by current methods will likely have

adverse consequences for some segments of the wolf population. Although some

short-term regulatory changes and the management of road access may need to be

considered to keep wolf harvest at a sustainable level, the most important consideration is to maintain long-term carrying capacity for deer, the principal prey for most of

the wolf population. A series of old-growth forest reserves may provide an effective

strategy to increase the likelihood that wolves will persist where extensive timber

harvesting has occurred, or is planned.

Keywords: Alexander Archipelago wolf, Canis lupus ligoni, effects of logging on

wildlife, population dynamics of wolves, predator-prey dynamics, roads and wolf

mortality, Tongass National Forest, southeast Alaska.

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Agriculture is dedicated to the principle of multiple

use management of the Nation’s forest resources for

sustained yields of wood, water, forage, wildlife, and

recreation. Through forestry research, cooperation with

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strives—as directed by Congress—to provide

increasingly greater service to a growing Nation.

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