CONCORD, N.H. – Winter ticks have taken a toll on the region’s moose herd, according to biologists in New Hampshire, Maine and Vermont.

In New Hampshire, 40 moose were collared near Berlin last fall in the first year of a five-year program to track the animals. The total included eight calves – all of which have died, said state Wildlife Director Steve Weber. Some adult animals also have died.

Officials believe the animals were weakened by thousands of ticks that cover their bodies and grow from the size of a fleck of pepper to the size of a lima bean by spring.

In an effort to rid themselves of the ticks, the moose rub their hair off, leaving them susceptible to exposure.

“This was very unexpected,” Weber told the state’s Fish and Game Commission on Wednesday. “We don’t think we lost every calf in the state this year, but certainly we can’t sustain this level of mortality without needing to make significant reductions” in the hunt in the future.

Loggers, rangers and others who work in the Maine woods also reported an unusually high number of dead moose, primarily young ones, last winter, said biologist Karen Morris of the Maine Department of Inland Fisheries and Wildlife.

She said ticks thrive when the autumn months are warm, allowing ticks to latch onto moose tightly, and the ground is bare of snow in spring when ticks are dropping their eggs.

With last winter’s lack of snow cover, there could be a strong tick population again this winter. If that’s the case, there could be more tick-related moose deaths late next winter, she said.

Cedric Alexander, district wildlife biologist and head of the moose management team at Vermont Department of Fish and Wildlife, agreed. Tick populations are cyclical and depend largely on weather. A snowy April is a powerful control on their populations, he said.

“We had a relatively heavy infestation this past winter,” he said.

About 200 of Vermont’s estimated 4,000 moose die each year, Alexander said. Of 42 reported moose deaths from March 1 to May 15, 13 had slight hair loss, 11 moderate hair loss and six severe hair loss, indicating they had been rubbing to try to rid themselves of ticks.

Alexander said it’s typical for an invested moose to have 30,000 to 40,000 ticks on it. He said a fully engorged tick is about the size of a grape.

Alexander said another good control is a well-managed moose herd. Denser moose populations tend to see higher infestations of ticks and other parasites, he said.

“If we can keep the population down to what is more natural density, hopefully we’ll avoid any severe impacts from things like winter ticks,” Alexander said.

Maine’s moose hunting season ended Oct. 12.

Vermont’s four-day moose hunting season begins Saturday. About three-quarters of the state will be open to hunting; 365 permits have been issued, Alexander said.

New Hampshire’s nine-day moose hunt also begins Saturday, when 485 hunters will head to the woods, 100 fewer than last year.