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Caribou: Central Alaska Network Resource Brief

Bull caribou

Denali •

Wrangell-St. Elias •

Yukon-Charley Rivers

Caribou Monitoring Status: Chisana Herd

Wrangell-St. Elias National Park and Preserve hosts 3 of 32 recognized caribou herds in Alaska. Of these, one herd is unique. The Chisana Caribou herd, whose range crosses the border between Alaska and Canada, is the only woodland caribou in Alaska. Woodland caribou are slightly larger than their alter ecotype, “barrenland” caribou, and are primarily found in the forested areas of Canada and the northern United States.

The Chisana Caribou herd was first surveyed in 1977 and has been consecutively tracked since 1986. Based on these surveys, observed caribou have numbered between 100 (1978) and 1,142 (1992). The Chisana caribou herd is important both because of its unique (in Alaska) woodland ecotype and because of its resource value to the region’s indigenous people. Because the Chisana herd has had such great fluctuations in herd size and has seen declines in recent decades, hunting of the Chisana caribou has been prohibited since 1994.

» Map:
2007 Chisana
survey area
WRST

» Table:
Chisana
population
estimates

» Photo:
Chisana
Caribou Herd
cow group

An intensive captive rearing program was conducted with the USGS and the Canadian Wildlife Service from 2003 through 2006. During calving, captured cows and offspring were protected from their major predators, wolves and bears. The hope was that improving calf survival would result in overall population growth. Surveys since 2003 reflect increased caribou numbers when compared to the prior 10 years. The most recent survey was conducted in October 2007 and results show a stable, slightly growing Chisana Caribou population.

In October 2007, the annual fall survey of the Chisana Caribou Herd was conducted by air over a 910 km² area in eastern Wrangell-St. Elias National Park & Preserve, Alaska, and western Canada. The goal of the survey was to estimate herd size and composition (number of cows, calves by sex, and bulls by 3 size classes). Herd location prior to the survey was determined by the distribution of 138 radiocollared females. During the two days of the survey, 719 caribou were observed, including 442 cows, 58 calves (25 males, 32 females, 1 unknown sex), and 219 bulls (66 small, 75 medium, 75 large). Since not all caribou that exist on the ground are seen by the researchers during the survey, statistics are applied the observed total. The result is a 2007 population estimate of 766 caribou in the Chisana herd, with a 90% degree of accuracy.

Based on the annual surveys since 2003, the Chisana Caribou Herd has maintained a fairly stable population of approximately 700 caribou. The most recent survey in 2007 shows an increase of 46 caribou since 2003 and 60 caribou since 2005. Only time and continued monitoring will reveal whether the Chisana Caribou Herd will grow in the future.

Monitoring Importance:

Caribou (Rangifer tarandus) occur in all three Central Alaska Network (CAKN) parks and are a keystone large mammal species in interior Alaska. They are critical to the northern ecosystems in which they live and have been an important source of food and raw materials for humans across thousands of years.

Caribou are of interest for monitoring from several perspectives. First, three of the four herds found in CAKN parks have experienced significant recent declines. Second, subsistence harvest on two herds has been curtailed due to conservation concerns, and providing the opportunity for subsistence activities is a directive for NPS lands in Alaska. Third, one herd is the subject of intensive interagency management, including the control of predators. Fourth, one herd is the subject of an international captive rearing conservation program which has significant long-term implications. Finally, long-term research and monitoring of caribou on CAKN lands provides a background against which future patterns may be compared.