Maine has the most moose. In one of the state’s moosiest areas, over 90% of calves tracked by biologists last winter died in their first year.
Accused? As Maine warms, a tiny creature is thriving.
“You look at one data sheet after another of what we found in the woods on these moose and it’s the same profile every time: winter tick,” said Maine Department of Inland Fisheries and Wildlife lead moose biologist Lee Kantar.
Winter ticks, also called moose ticks, have plagued Maine moose for at least a century. In Maine, New Hampshire, Minnesota, and southern Canada, their populations have soared. Biologists and hunters often find moose with 40,000, 75,000, or 90,000 ticks. Ghost moose are infested moose that rub themselves bald to remove ticks.
Many adult cows can survivе such a massive tick load. Calves are another story, however.
Of the 70 moose calves that DIF&W collared in a remote wildlife management district spanning parts of Piscataquis and Somerset counties last winter, 60 of them had died by the beginning of May. That’s 86% — a record high mortality rate since DIF&W began the tracking survey.
“That’s how detrimental these ticks are,” Kantar said. “And it is pretty incredible.”
The surge has been apparently driven by a combination of a warming climate and — at least in parts of Maine and New Hampshire — moose populations that are so dense that it’s easy for larval ticks to find a host.
“Those populations up there are really high density,” said Alexej Siren, a postdoctoral researcher at the University of Vermont, said of the prime moose habitat that extends from northern New Hampshire across north-central Maine to parts of Piscataquis counties. “It’s on a very different scale than other areas of New England as far as other moose habitat that’s out there.”
Unlikе deer and dog ticks, winter ticks literally hunt in packs. Larvae gather in interlocking clumps on vegetation, and when one tick snags a passing victim, hundreds or thousands tag along for the ride. A solid coating of snow or a sustained cold snap kiII those larvae and stop the hunt, which scientists call “questing.” But snow has been arriving later in the fall across northern New England.
“The winters have shortened and the falls are longer, which means longer time for those ticks to quest and actively seek their host, which means (moose) have accumulated much more on them,” said Siren, who has worked closely with Kantar and his counterparts in New Hampshire.
“Core moose habitat in New Hampshire is the White Mountains and north, and winter ticks are still the major factor influencing that population,” said Fish & Game Department lead moose biologist Henry Jones. Development reduces moose populations in southern New Hampshire and Maine, reducing winter ticks. In the enormous commercial forests up north, decades of clearcutting and regular harvesting have created great moose habitat.
Ticks won’t kiII moose in Maine or New Hampshire, but Jones said climate change is helping the parasites take hold in some locations.
“Essentially you had this species, moose, that came in and found all of this food, no predator,” Jones said. They multiplied. It’s falling again. Winter ticks are predators, and the warming climate enhances them.
Maine IF&W is also investigating if reducing adult moose concentrations in the area where the calves were collared can cut winter tick levels and improve population health. Divide the 2,000-square-mile wildlife management district from the Quebec border to Baxter State Park’s western edge. One portion allows more hunting, whereas the other does not.
The winter tick epidemic is kiIIing moose.
Winter ticks may potentially be causing Maine and northern New England moose cows to miscarry.
Kantar left DIF&W’s Greenville office in late April to investigate a moose’s dеаth that had been on his agency’s radar for over a decade.
Biologists collared and released a baby moose in Rockwood’s woodlands in 2014. Moose Number 59, as documented on her ear tag, wandered a forest near Moosehead Lake for eight years until an antler hunter found her fresh carcass in late April and called her tag number.