FAIRBANKS, Alaska — The largest caribou herd in Interior Alaska has grown to a level not seen since the 1920s, according to a preliminary count from a photo census.
The census conducted in July places the Fortymile Caribou Herd with a population of more than 71,000. The herd had a population of about 51,000 in 2010, the Fairbanks Daily News-Miner reported .
The 2017 number is still preliminary as the herd has only been counted once from the aerial photographs used for the census, said Jeff Gross, a biologist with the Alaska Department of Fish and Game.
A crew from inside an airplane photographed the herd during a five-hour period on one day in July, Gross said. Caribou typically stay together in large herds, making it possible to photograph the herd all at one time.
While one plane was photographing, five other planes were tracking caribou wearing radio collars.
“We use the number of collars that we find throughout the day to gauge what percentage of the herd is likely in the photographs,” Gross said. “We had probably 95 percent or better of the radio collars in the groups we photographed.”
This herd migrates between Canada’s Yukon territory and the White Mountains north of Fairbanks. The herd has experienced drastic population booms and declines since the count began. In the 1970s, the herd’s population dropped to about 5,000.
Researchers do not have an answer yet for why the herd has experienced this latest growth spurt.
“That’s a big, big question, and something we’ll be working toward,” Gross said.
The state’s management plan for the herd aims to increase its size between 2 percent and 3 percent each year.
Information from: Fairbanks (Alaska) Daily News-Miner, http://www.newsminer.com