October 30, 2013

Maine moose herd ‘robust’ while population falls elsewhere

From staff and wire reports

Maine’s moose population is healthy and not experiencing the same conditions that are causing problems with moose herds in other states, according to a state wildlife biologist.

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A moose walks along Route 11 just north of Patten. Maine’s moose population has plenty of habitat on commercial forestlands.

2013 Press Herald File Photo/Gabe Souza

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Lee Kantar, a wildlife biologist and moose specialist with the Maine Department of Inland Fisheries and Wildlife, said Maine’s moose population is “healthy and robust” with plenty of habitat on commercial forestlands.

There are about 70,000 moose in Maine, one of the highest densities in the lower 48 states, he said.

Despite the trend in Maine, moose in other parts of the northern United States are dying in what some 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.

Kantar, the Maine biologist, said broad reports of a moose die-off in North America are problematic because there are many differences in habitat and other factors between states.

For example, areas with larger populations of white-tailed deer are more likely to see moose affected by brain parasites, while that is less of an issue in Maine, he said.

“When you look at moose range across North America, things are very, very different from the West Coast to the East Coast with moose,” Kantar said.

No single cause seems to be responsible for the population declines in other states.

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.

And in New Hampshire, massive tick infections seem to be the culprit.

However, that diversity of reasons makes some experts think they need to dig deeper for a possible connection.

“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.

Staff Writer Gillian Graham contributed to this report.

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