There is a paucity of data concerning wolf (Canis lupus) demography, m
ovement patterns, and predation characteristics in relation to migrato
ry caribou (Rangifer tarandus granti). Consequently, during 1987 throu
gh 1992, we studied wolves and the Western Arctic Caribou Herd in nort
hwestern Alaska. We captured and radio collared 96 wolves in 19 packs
and relocated them ion 1,830 occasions. Wolf packs usually did not fol
low migratory caribou but maintained year-round resident territories t
hat averaged 1,868 km(2). However, during years when caribou were abse
nt and moose (Alces alces) densities were low, up to 17% of the radio-
marked wolf packs followed migratory caribou and then returned to thei
r original territory for denning. Radio-collared wolves (n = 21) dispe
rsed primarily during April through September. Spring wolf densities i
ncreased from 2.7 to 4.4 wolves/1,000 km(2) during 1987 through 1990,
and then declined to 1.5 wolves/1,000 km(2) following a rabies epizoot
ic. Annual wolf survival rates averaged 0.552 (rang = 0.464-0.656). An
nual survival during 1990-91 and 1991-92 was lower than other years du
e to a rabies epizootic. Overall, hunting was the main cause of death
(69%) for wolves (n = 52). Most (63%) mortality occurred during Decemb
er through March when snow cover permitted wolf hunting from snowmobil
es. Caribou and moose composed 51 and 42%, respectively, of the kills
observed during the study; 59% of caribou and 64% of moose kills were
adults. Ungulate kills averaged 4.6/wolf/100 days and provided 5.3 kg
of available food/wolf/day. In northwest Alaska, caribou were the prin
cipal prey when present within areas by wolves. However, when caribou
densities were <200/1,000 km(2), wolves switched to preying on residen
t moose. Wolves within the range of the Western Arctic Caribou Herd ki
lled 6-7% of this caribou population annually. Caribou left wolf pack
territories during winter, and wolves switched to preying on moose for
approximately 4 months of each year. Wolves killed from 11 to 14% of
the moose population annually. Wolf densities were limited by hunting
and trapping, and wolf predation at levels found in 1987-91 did not st
rongly limit caribou population growth. However, existing wolf populat
ions may be able to regulate local, low-density moose populations that
have become established during the past 40 years.