MONSON, Maine (AP) — Infestations of ticks contributed to a record high death rate for young moose tracked by wildlife managers in rural Maine.

The Maine Department of Inland Fisheries & Wildlife collared 70 moose calves in remote parts of the state last winter and 60 of them had died by the beginning of May, Maine Public reported. The 86% mortality rate was the highest since the agency started the tracking survey.

Lee Kantar, the moose biologist with the wildlife department, said the winter ticks are to blame. The ticks, also called moose ticks, are a worsening problem in the areas of the northern U.S. and southern Canada that moose call home.

Short winters and long falls have given the ticks more time to seek out moose, and the moose have accumulated larger numbers of them, biologists said. The ticks can gather on moose in the tens of thousands and can bleed the animals to the point of death.

Maine moose are also coping with other parasites, such as brainworms. The giant animals are the largest member of the deer family and they are Maine’s official state animal.