What’s happening to all the moose?

Moose in the northern United States are dying in what scientists say may be the start of climate shock to the world’s boreal forests.

The die-off is most dire in Minnesota, where ecologists say moose could be gone within a decade. But it extends across the southern edge of the animal’s global range: Populations are falling as far away as Sweden.

No single cause seems to be responsible. In Minnesota, many moose seem to be dying of parasitic worms called liver flukes; in Wyoming, some researchers are pointing to a worm that blocks the moose’s carotid arteries; in New Hampshire, massive tick infections seem to be the culprit. This diversity of reasons makes some experts think they need to dig deeper.

“The fact that you’ve got different proximate causes killing off the moose suggests there’s an underlying ultimate cause,” says Dennis Murray, a population ecologist at Trent University in Canada.

Murray suspects that the underlying cause is climate change. Moose are adapted to the bitter cold of northern climates, and those living farther north in Canada and in northern Scandinavia appear healthy for the most part. But moose in southerly habitats can become heat-stressed when the weather gets warm. This prevents them from building body-fat reserves to help them survive the winter. Heat stress may also weaken their immune systems and make them more susceptible to parasites, a link that is well established for cattle in Africa.

Indeed, Murray and his colleagues have found that moose populations in Minnesota decline more quickly in years with warmer summers. Parasites – and their main hosts, white-tailed deer – are also more likely to survive the milder winters of recent years, says Ron Moen of the University of Minnesota at Duluth.

Researchers have yet to prove a link to climate change. But Murray notes that lynx and snowshoe hares also are declining in the southern parts of their ranges. “We’re in the process of seeing a pretty dramatic change in the distribution of the boreal forest ecosystem,” he says.

More in Local News

Inslee’s budget solves school funding with help from carbon

His budget would use reserves to boost education, then replenish them with a carbon tax or fee.

Man, 29, injured by shots fired at Everett thrift store

The gunfire followed an argument in the parking lot of Value Village on Evergreen Way.

In adult court, four teens plead not guilty to murder

Prosecutors allege they worked together to plan and execute a drug robbery in Everett.

Lynnwood robbery leads to lockdown at Edmonds schools

Edmonds police said it was just a precaution as they search around Edmonds-Woodway High School.

Marysville 7-Eleven hit by armed robbers

Officers set up a perimeter and brought in a police dog, but the man couldn’t be found.

2 women struck, injured while crossing busy roads

The first happened Wednesday night in Everett. The second was Thursday morning in Edmonds.

One dead in crash south of Granite Falls

Two cars collided near the intersection of N. Lake Roesiger Road and Hidden Valley Road.

Old Silvana Creamery recalling whole raw milk

The milk was sold at the farm store, directly to customers and at local stores.

Police looking for leads in case of missing Snohomish man

Henry John Groeneveld, 63, was last seen on Monday, when he said something about going to “the river.”

Most Read