The Alexander Archipelago Wolf: A Conservation Assessment
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....
The Alexander Archipelago
Wolf: A Conservation
David K. Person, Matthew Kirchhoff,
Victor Van Ballenberghe, George C. Iverson,
and Edward Grossman
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
The Alexander Archipelago Wolf:
A Conservation Assessment
David K. Person
Victor Van Ballenberghe
George C. Iverson
U.S. Department of Agriculture
Pacific Northwest Research Station
General Technical Report PNW-GTR-384
In cooperation with:
U.S. Fish and Wildlife Service
Alaska Department of Fish and Game
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. Infor-
mation 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 considera-
tion 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.
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]) pre-
sumably 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 com-
position, 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 esti-
mates 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 de-
termined 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
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 preda-
tion is primarily additive. We cannot suggest a minimum deer population because we
do not know what would constitute a minimum viable wolf population either demo-
graphically or genetically. Nevertheless, if we expect to sustain the current post-
denning population of 250 to 300 wolves on Prince of Wales Island (along with sub-
sistence 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 popula-
tion of wolves in southeast Alaska. The area of most immediate concern is game
management unit 2, including Prince of Wales and Kosciusko Islands.