The caribou herd that used to be the largest in Alaska and, at times, the largest in North America has continued to shrink, fitting an Arctic-wide pattern that scientists have linked at least in part to climate change.
The Western Arctic Caribou Herd population now stands at 152,000, down from 164,000 last year, according to the most recent survey conducted by the Alaska Department of Fish and Game and its partners.
The herd’s population numbers and trends were detailed last week at the annual meeting of the Western Arctic Caribou Herd Working Group, an advisory organization representing village residents and hunting and conservation organizations.
The herd, which roams over a vast territory that ranges from the North Slope and Chukchi Sea coast to Interior Alaska, has long been a source of food and culture in many Indigenous communities. That makes its welfare an issue of food security and cultural preservation in some areas.
This year’s count, calculated through photographic records, represents a continued downward trend since 2017, when the herd size was estimated at 259,000.
“Within that short timeframe, we’ve lost 100,000 caribou within this population, which is significant,” Alex Hansen, Fish and Game’s Kotzebue-based biologist who monitors the herd, told the working group last Wednesday during the Anchorage meeting.
The Western Arctic herd size peaked at 490,000 in 2003. Over the past half-century, its size has veered between extremes, nosediving from 242,000 in 1970 to 75,000 in 1976 before rebounding after strict hunting rules were put in place.
Hunting has also been sharply restricted in recent years, and the working group endorsed continued limits.
It is not just the number of caribou hunted that’s important to the herd’s potential recovery, Hansen stressed in his presentation. It is also important to avoid taking females out of the population, he said.
“One cow has a lot of potential to produce more caribou,” he said. The message in his PowerPoint presentation was boiled down to a succinct phrase: “Let cows live.”
But Hansen acknowledged that there are reasons that some hunters might prefer to target cows during their harvests, which tend to be in autumn, when the bulls are hormonally charged and geared toward mating.
“Cows are fat. They’re better to eat. Nobody wants to eat a rutty bull,” he said.
Working group members said they believe tools exist to help turn around the decline.
“By slowing down the decline now, hopefully it won’t bottom out at the low level that it did in 1976,” said Charles Lean, a working group member from Nome.
Within the total population estimates, there are other trends.
For adult females, survival rates are lower than the long-term average. However, the rate of birth of new calves is a bit above the long-term average.
Migration patterns have changed significantly over recent years, Kyle Joly, a National Park Service biologist who studies the herd, said in a presentation to the working group.
Caribou in the herd are generally staying farther north in the fall and winter, according to monitoring conducted by radio collar signals. A much smaller percentage of collared animals even venture south far enough to cross the Kobuk River, a site that used to be a regular transit point during the fall migration, the data shows. Among those that do cross the river, the season’s first crossings are now a month later than they were 10 years ago, he said.
Herds declining across North America
The Western Arctic herd’s decline is part of a wider pattern.
Caribou herds across North America have been shrinking, as are wild reindeer herds in Arctic Eurasia. Scientists say climate change and industrial development are factors adding to what are the normal wide swings in population. Climate change adds risks like increased rain-on-snow events, which makes travel and food foraging difficult, and is replacing low-lying lichen and other vegetation that caribou eat with woody shrubs. Meanwhile, industrial development is fragmenting habitat, creating roads and other infrastructure that have become impediments to caribou movement.
Some of the most extreme caribou herd crashes have been in Canada.
The George River Caribou Herd, which ranges in land in Quebec and Labrador, was about 800,000 animals in the 1990s but is now down to only 7,200 as of last year. It was once the world’s largest herd.
The Bathurst Caribou Herd in Canada’s Northwest Territories declined from 186,000 in 2003 to 6,240 in 2021, according to the territorial government. Some Canadian herds have already been declared extinct, and several are classified by the government there as at risk.
Along with the Western Arctic herd, other major Alaska herds have declined, as Joly pointed out in a presentation to the Western Arctic Caribou Herd Working Group.
The Fortymile herd in eastern Interior Alaska has declined by over 50% in six years; the Nelchina herd, also in eastern Interior Alaska, has dropped by over 80% in four years; and the Mulchatna herd in Western Alaska is down by 98% from its 1990s size, according to his presentation.
With declines in the Western Arctic and other herds, that leaves the Porcupine Caribou Herd as potentially the largest in North America. The Porcupine herd ranges between northeastern Alaska and neighboring parts of Canada, and it is known for using the narrow Arctic National Refuge coastal plain for annual calving.
However, recent figures for the Porcupine herd are not available. The last official photo census, which put the population estimate at over 218,000, was in 2017.
Like the Porcupine herd, two other North Slope herds appear to have bucked the decline trend.
The Central Arctic Caribou Herd, which has fluctuated widely in its size over the years, peaked in 2010 at 68,000 animals, then shrank to 23,000 in 2016 before increasing to over 34,000 by 2022, according to the Alaska Department of Fish and Game. The Teshekpuk Caribou Herd, which spends the entire year on the North Slope, The Teshekpuk Caribou herd grew from 40,000 in 2011 to 61,500 as of 2022, according to the Alaska Department of Fish and Game and the U.S. Bureau of Land Management.
