A few years ago, I was driving through Northern Maine on my way to hike Mt. Katahdin, the state’s highest peak and terminus of the Appalachian Trail. A small crowd of hunters had gathered outside a game inspection station, and I stopped to see what they’d shot. A jolly man in an orange vest was beaming. He’d killed a moose—his first one ever, and it was tied onto a trailer behind his truck. A little boy bounced beside it, slapping the dead moose on its hairy back.
Other than that one, moose in Maine actually aren’t in trouble—in fact, they’re doing so well that the state is considering raising the annual number of moose hunting permits to 4,000 (up from 3,725). The same cannot be said for much of the northern United States, including Montana, where the moose population has been declining for over 15 years. Now scientists there are trying to figure out why.
This winter, biologists from Montana’s Department of Fish, Wildlife and Parks (FWP) are putting radio collars on up to 90 female moose, starting in the Cabinet Mountains in the northwestern part of the state. “Moose can live for a long time, so we had to commit to doing it for a while to get a good sample size,” Nick DeCesare, a FWP biologist told the Bozeman Daily Chronicle. So for the next decade, the scientists will track them, recording births, survival, and movement in a quest to figure out what's killing moose.
There are a lot of theories about what’s causing the population decline. Scientists suspect warmer winters could partially be to blame. In northeast Minnesota, where the moose population is shrinking at 20 percent a year and hunting them is banned, biologists believe moose are struggling from winter heat stress, which happens when winter temperatures rise above 20 degrees. Warmth also helps parasites survive. In Wyoming, researchers found that about half of the moose killed in the state’s 2009 hunting season were infected with an artery-dwelling worm. And ticks are able to survive to prey upon the animals in the tens of thousands (scientists once found 120,000 ticks on a single moose). Itchy ticks cause moose to rub, wearing their coats thread-bare and threatening them with hypothermia. The blood-suckers can also cause anemia.
The Montana researchers also suspect a lack of logging could play a role in the moose’s trouble. Moose depend on early successional vegetation like grasses, saplings and shrubs, but as logging has declined, trees are growing back. On the flip side, too much disturbance also harms the gangly animals: in Yellowstone National Park, the huge fires of 1988 contributed to the population decline by destroying moose habitat in more than a third of the park.
Of course, many people think that wolves are responsible. The state’s moose population started shrinking around the time that gray wolves were introduced into the Northern Rockies, in the late 1990s, and Ken McDonald, who heads up the wildlife division of FWP, says some are quick to link the two events. McDonald says he’s had people question the need for a moose study, telling him, “We already know what’s killing them. It’s the wolves.”
DeCesare, the wildlife biologist, said that while he’s going to consider the impact of wolves, he suspects moose are dying from other causes, too. In Minnesota, which has wolves, scientists have found intact dead moose just lying on the ground with no signs of having been killed by wolves.
In response to Montana’s decline, game mangers have scaled back the number of moose hunting permits, and hunters that do snag one say it’s much harder to find moose than in the past. For those jonesin’ for a chance to shoot a moose, there is one other option: the state's annual moose permit auction. In 2012, a single moose permit sold for $16,000, and the proceeds are helping to fund the moose study. That’s a bargain compared to the bighorn sheep permit, which sold for $480,000.
Emily Guerin is the assistant online editor at High Country News.
Photo courtesy Flickr user Bill Gracey.