Almost three-fourths of the 36 calves being tracked in New Hampshire have died because of tick infestation, reports show.
While official figures are yet to be released, a high number of moose deaths have been linked to these blood-sucking insects.
In January, a group of wildlife biologists in Maine teamed up with the Native Range Capture Services to study the moose population in the northeastern part of the United States. Using radio collars, they tagged several calves to analyze the animal's survival skills.
According to Lee Kantar, the state's moose biologist, the northern part of Maine has lower calf mortality rates. Moreover, when compared to white-tailed deer, moose are not good in grooming themselves to keep the ticks off during the fall.
"The winter tick is on the moose all winter up until right now when moose are molting and shedding their winter coat and so the three life stages, larvae, nymph and adult are all operating at the moose, taking blood meals on those three occasions," added Kantar.
The calf-tagging activity is part of a study that kicked off in 2014, which aims to understand the moose population decline in the region.
A single moose can host up to 75,000 ticks a time on its body. These parasites pile up in large numbers on high plants around November while waiting for a moose to pass by.
They latch on to the animal and spend the winter feeding off the animal's blood. When spring comes, many of the tick-infested moose become extremely thin and eventually die.
Winter ticks are highly dependent on the density of the moose population and short winters.
"It doesn't bode well for moose in the long term if we continue to have these short winters. As our moose numbers decline, the ticks will decline, as well. What we don't know is at what point will things level off," said moose biologist Kristine Rines.
Normally, winter ticks fall off the dead animal and die because of cold conditions. However, the shorter winters and warmer climate change the game, allowing the ticks to simply walk away - alive - in search of a new animal as their host.