COEUR D’ALENE, Idaho — Officials in British Columbia will use helicopter gunners to shoot up to 24 wolves just north of the Idaho border this winter in an effort to save the 18 remaining southern Selkirk Mountains woodland caribou in a herd from extinction.

The Spokesman Review reports that both the caribou and wolves roam across the Canadian border into north Idaho and northeast Washington. The herd has struggled from losses of old-growth habitat and other issues. Snowmobiling has been restricted in most of the core recovery area in Canada and the United States.

The South Selkirk herd was 46 strong in 2009, but it dropped to 27 in 2012, officials said. The latest survey puts the herd at 18. The caribou are listed as endangered species in the U.S. and British Columbia.

Wolves are the leading cause of the decline, officials said.

The Ministry of Forests, Lands and Natural Resources announced the wolf-removal plan this week, but the agency has been working on it for more than a year, said Wayne Wakkinen, Idaho Fish and Game Department regional wildlife manager in Coeur d’Alene.

Idaho and Washington wildlife officials were consulted, as well as First Nations, the U.S. Forest Service and the U.S. Fish and Wildlife Service, Canadian officials said.