Kecology of Caribou 
at Prudhoe Bay, Alaska 
ROBERT G. WHITE, BRIAN R. THOMSON*, TERGE SKOGLAND**, 
STEVEN J. PERSON, DONALD E. RUSSELL***, 
DAN F. HOLLEMAN, AND JACK R. LUICK 
Institute of Arctic Biology 
University of Alaska 
Fairbanks, Alaska 99701 
Introduction 
The U.S. IBP Tundra Biome study area at 
Prudhoe Bay, Alaska, is located on the northern 
coastal plain bordered by the Kuparuk River in 
the west and the Sagavanirktok River in the east. 
This same area is the site of oil exploration, and 
the road system which has been constructed for 
this purpose allows easy access to most of the 
area between these rivers and to approximately 
7 km inland (Fig. 1). 
Prudhoe Bay lies on the periphery of the 
summer range of two large populations of bar- 
ren-ground caribou (Rangifer tarandus granti). 
The western part of the Arctic Herd may move 
into the area from the west in June-July (Hem- 
ming 1971), and occasionally the outer (west- 
ern) periphery of the Porcupine Herd moves in 
from the east. However, most movement into 
the Prudhoe Bay area is thought to be from a 
large central section of the Arctic Herd (Hem- 
ming 1971). These animals move through Anak- 
tuvuk Pass and down the Colville River, or 
through the Dietrich and Atigun areas and down 
the Canning, Sagavanirktok and Kuparuk Rivers 
(Hemming 1971; Gavin 1975) to graze on the 
coastal plains from late June through Septem- 
ber. There is also evidence of a small population 
which remains in the Prudhoe Bay area year- 
round (Child 1973; Gavin 1975). 
The summer vegetation of the Arctic tundra 
is thought to be of high nutritive value. Rapidly 
growing vegetation is of high soluble carbo- 
hydrate, soluble nitrogen (N), and phosphorus 
(P) levels because of the long daylight hours. 
Thus, the relatively short growing season is 
complemented by high relative growth rates. 
Since it is considered that summer nutrition is 
important in affecting the body condition of 
animals entering the winter, the quality and 
quantity of forage removed from the summer 
range is potentially important in affecting the 
productive performance of these caribou. This 
may be relatively more important to the calf 
crop, as growth rates of caribou calves are 
normally high, and any restriction in nutrition 
during this stage of rapid growth may lower the 
likelihood of surviving the winter. 
*Current address: Department of Forestry and Natural Resources, University of Edinburgh, Scotland, U. K. 
**Current address: Statens Viltundersokelser, Elgeseter gt. 10, Trondheim, Norway. 
***Current address: Faculty of Forestry, University of British Columbia, Vancouver 8, British Columbia, Canada. 
