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Ticks Kill Moose At High Rates As New England Winters Warm

Northeast Naturalist via Flickr CC

Researchers have finished their largest study to date on how ticks and warming winters are hurting moose in Northern New England.

The data shows unprecedented death rates among moose calves -- more than 50 percent in four of the past five years, plus lower reproductive rates in adult moose across Maine, New Hampshire and Vermont.

UNH ecologist Peter Pekins says the animals are spending months covered in tens of thousands of blood-sucking winter ticks – a different species than what bites humans.

“At the southern limit of the range, this is where climate change has most impact, because our winters are starting later,” he says. “So this gives these larval ticks more time to find, or what’s termed quest, for a host.”

(Click here to read the full study, published in the Canadian Journal of Zoology.)

Pekins says this comes after decades of moose thriving farther south than they'd normally live, because Northern New England's commercial forestry creates a steady supply of young trees for them to eat.

Now, that means they overlap more with winter ticks – which they're not evolved to fight – while moose also struggle with a deer-borne brainworm and unsuitably warm conditions in general.

Credit Dan Bergeron / NH Fish & Game
NH Fish & Game
This adult "ghost moose" has rubbed off much of its fur while trying to remove winter ticks.

“The joke is moose are so big they attract all the problems,” Pekins says.

Pekins says the ticks alone will mean a slow decline to a much smaller moose population within 20 years.

He says this puts wildlife managers in “new territory.”

They can cull the moose numbers through hunting to give the ticks less to feed on, which would help restore a healthy population more quickly – or they can let nature, skewed by climate change, take its course.

“That’s really the question for the agencies probably will be facing – how do we manage a population in the face of environmental conditions that limit its productivity?” Pekins says. “And can we – should we – be managing this population at a different level when considering the impacts of the environment?”

Regulators may tackle that question in the coming months, while researchers continue to monitor the effect of ticks on moose they’ve tagged with radio collars.

Pekins says those moose will begin to pick up this winter’s ticks this month.

Annie has covered the environment, energy, climate change and the Seacoast region for NHPR since 2017. She leads the newsroom's climate reporting project, By Degrees.

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