- Herd size (2022) 40,000
The Fortymile herd migrates between Alaska and Yukon. It was once estimated at about 600,000, and its range stretched from Whitehorse to Anchorage. By 1974, the herd was estimated at about 4,000, and it stopped migrating to Yukon. Conservation actions, including hunting restrictions and the sterilization of wolf packs were taken and the herd grew, although recent research suggests that wolf control was not a significant factor in the herd’s increase. By 2002 it was once again migrating into Yukon. In 2017 the estimated herd size was 71,000. The Alaska Department of Fish and Game says "The herd began to show signs of declining nutritional status after it exceeded 50,000 caribou in 2010." In summer 2022, the Department estimated the herd size at 40,000. Increased hunting quotas had been set by the Alaskan government in the previous two years to take the strain off perceived overpopulation. After it's new (2022) population estimate, the Department said, "department staff continued to observe low productivity in the herd this spring and above average mortality of newborn calves this summer, indicating continuing nutritional stress and low potential for herd growth."
Tactical departures and strategic arrivals: Divergent effects of climate and weather on caribou spring migrations
Demography of an increasing caribou herd with restricted wolf control: Caribou Demography and Wolves