New England’s Moose Are Losing the Fight Against Winter Ticks

Josh Blouin, a wildlife biologist with the Vermont Fish and Wildlife Department, was waiting outside an old general store in Island Pond Vermont at dawn on an October morning to hopefully see a moose. Blouin, a Vermont Fish and Wildlife Department wildlife biologist, sipped on his coffee and explained that while telemetry would allow him to track the huge ungulates but actually seeing one would require him to creep slowly and quietly through the woods which were unfortunately covered in crisp fallen leaves.
It's a routine for Blouin. Since 2017, Blouin has worn snowshoes, rainboots, or hiking boots every day. He has been trekking into Vermont's hardwood forests to watch radio-collared members of the department's moose herd, trying to find out why Vermont's population has dropped by 45 percent in a mere ten years. Blouins fieldwork revealed some troubling numbers that he and his coworkers published in a paper last summer. From 2017 to 2019, 66 percent of moose calves survived the first 60 days. Only 49% survived the first winter. Half of all birth rates fell.

These huge animals are dying. Teeny, tiny ticks.

Blouin was not the only one searching for moose on that particular day. Winter ticks begin to search for a host organism in October. They form teams of about a thousand and interlock their limbs so that if one tick grabs onto someone, all the others follow suit. These ticks are warm-blooded and can be found in any warm-blooded host. However, moose are a good choice. Blouin states that moose do not have a natural grooming instinct and they have a thick eight-inch coat which keeps ticks warm. They live a happy life.

Winter ticks are more active than other ticks. They spend five months molting from larvae through nymph to adult, and do not spread disease. The earliest winter season is when moose calves are six months old. Pregnant cows cannot make enough blood to replenish their bodies. They are often anemic, malnourished and confused by spring. Blouin states that they die slowly and painfully.

He calls April his mortality month. Radio collars transmit messages to his phone, as many as three per day, when a moose has stopped moving. Blouin's necropsy carcasses are nearly bald and covered with as many as 70,000 ticks. These magnificent animals are covered in skin and bones. He says it is a very sad sight. Even those moose who survive winter are less fertile and physically exhausted.

Although winter ticks aren't new to the landscape they are becoming more common with climate change. The ticks have more time to find a host because of long autumns and late snow. Parasites also prefer earlier springs. They eventually drop off the moose in March. Female ticks that fall on snow will die, while those that fall onto leaf litter can lay up to 4,000 eggs. This kind of weather was once an exception in New England. It is now the norm.