N.H.'s Moose Population Decimated by Winter Ticks

Jan 23, 2017

 New Hampshire's moose population is down to just over 4,000 animals, facing an unprecedented die off because of winter ticks, according to UNH Wildlife Ecology professor Pete Pekins. 

Speaking on The Exchange, Pekins says winter ticks have taken an especially harsh toll on moose calves each spring for the past three years -- one of several alarming findings in a four-year study of the state's moose population, involving the N.H. Fish and Game department and UNH. 

Previous moose population studies have not shown such a high mortality rate, Pekins says: 

"…We collared 100 animals and in April 2003 started losing calves in the best habitat possible.  It quickly became apparent the tick infestation was off the charts. I distinctly remember there was no winter that year.  We had 50% calf mortality then.  For the next three years it did not happen again.  The major difference this year -- and for the last three years -- we had 70% mortality of calves."

Pekins says the number of ticks found on the calf carcasses ranges from 35,000-96,000 ticks.  "It's just physiologically impossible for these animals to deal with that; it's too much blood loss in a very short period of time."

A warming climate has allowed these tiny parasites to thrive, he says:   "This is a parasite problem and that parasite is related to longer falls that allow this parasite to have an advantage that may extend into a moderate moose density.  And that’s what we don’t know -  because this is really new ground that we’re looking at."

Kent Gustafson, of the NH Fish and Game Department, which manages the state's moose population, notes that tick impacts farther south, even with warm winters, are not as drastic as in the north country.  More moose make the region hospitable for more ticks:  "It appears as if this density relationship is something worth seriously considering.  And it is counter-intuitive. But by reducing densities you may have fewer moose, but healthier moose, and more productive moose."

Gustafson said the peak number of moose hunting permits was over 600 in the early to mid-2000's.  Last year the number was down to 70 permits to hunt moose.