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States Study Decline In Moose Population

For the first time, Vermont Fish & Wildlife officials counted the number of winter ticks found on harvested moose. Winter ticks have been blamed for unintended lowering of moose populations in the midwestern U.S. and elsewhere. Courtesy Photo -- Wayne LaRouche

For the first time, Vermont Fish & Wildlife officials counted the number of winter ticks found on harvested moose. Winter ticks have been blamed for unintended lowering of moose populations in the midwestern U.S. and elsewhere. Courtesy Photo -- Wayne LaRouche

Moose population figures are on a downward trend in New Hampshire and Vermont, in part because of officials’ efforts to reduce them. Now, both states are taking steps to determine why more are disappearing than expected.

In January, New Hampshire Fish & Game will begin a four-year monitoring of 80-90 Granite State moose with the use of radio collars. When one of the animals dies, the collar will stop transmitting signals and biologists will study the animal to determine a cause of death.

In Vermont, the Fish & Wildlife Department, for the first time, counted the number of winter ticks attached to the bodies of harvested moose, taking on a practice conducted for the last several years in New Hampshire. Winter ticks latch on to moose in mid fall and survive through the winter, increasing mortality rates because of weight loss and hypothermia that can occur when the animals scratch so often they lose fur.

Both New Hampshire and Vermont have seen a drastic population decline in recent years. The Granite State’s moose population shrank from about 7,600 in 1996 to 4,400 prior to this year’s hunting season. In Vermont, the population has nearly halved since a 2005 figure that stood at about 5,000.

Part of the decline has been intentional, with increased hunting permits issued throughout much of the last decade to help curb populations. Especially in New Hampshire, concerns included vehicle collisions — more than 200 moose per year were killed in Granite State vehicle accidents between 1996 and 2002 — as well as overtaxed food sources that caused low birth rates and body weights.

Vermont moose hunting permits was up to 1,255 in 2008, but has come down dramatically as moose population figures have declined. There were 363 issued this year.

“The population figures we have now are what we had targeted,” said Scott Darling, Vermont F&W’s Wildlife Management Program Director. “That’s not the surprising part, or the problem. The problem is that winter ticks are thriving more and more and result in (unintended) moralities.”

About the size of a grain of sand, winter tick larvae mass on low-lying vegetation and latch onto moose when they walk by. By the spring, many moose are afflicted with 30,000-100,000 ticks, according to Vermont wildlife biologist Cedric Alexander. Some of them are the size of grapes.

The number of winter ticks varies greatly from year to year and depends largely on early- and late-season snow pack.

“When they drop off in late March/early April to lay eggs, they lay a lot fewer of them of if there’s snow pack on the ground,” Darling said. “If there’s little or no snow pack in March and April, and then again in November, that’s when you’re going to see the most winter ticks.”

Winter ticks have also affected moose populations in the Great Lakes region, and were first monitored in New Hampshire during a five-year radio collar study from 2001-06. The study that begins in January will take a closer look at what causes moose mortality, from winter ticks to other ailments, including ingestion of the cadmium metal because of acid rain, brain worm parasites and the ked horsefly.

“We want to get an update on the status of the winter tick and look at a number of other issues,” said New Hampshire moose project leader Kris Rines. “There are a lot of environmental factors that may be contributing to moose mortality.”

The new study is funded by federal Wildlife Restoration money.

Vermont hunters had a 54 percent success rate during their nine-day moose season ending Oct. 24, up from 52 percent last year. New Hampshire’s 64 percent success rate was identical to last year’s during its nine-day season ending Oct. 27.

Jared Pendak can be reached at jpendak@vnews.com or 603-727-3306.