They caused about half the calf deaths between 20 in Maine and New Hampshire, said Pete Pekins, a retired University of New Hampshire wildlife biologist. In the state’s northeast, the population is down from more than 8,000 in the mid-2000s to 3,000-4,000 today.Ĭlimate change may be eroding their ability to cope with disease and parasites, Carstensen said, although ticks have played only a minor role in the decline.īut ticks are rampaging in New England, which has by far the highest moose population in the Lower 48 states. Few remain in northwestern Minnesota, where thousands roamed a few decades ago. That helps explain why Isle Royale’s moose numbers have risen to around 1,800 in recent years, despite the ticks. Isle Royale has no deer, so its moose aren’t exposed to brainworm, a deadly parasite that deer carry. Its only moose predators are wolves, which nearly died out before officials began restoring the population in 2018 with mainland substitutes. “But this new paper says, ‘Not so fast - these subtle changes during summers can be exacerbating some of these effects and you need to pay attention to that as well,’” said Michelle Carstensen, wildlife health program supervisor with the Minnesota Department of Natural Resources.Ĭarstensen, who did not participate in the study, said it’s enlightening, but she noted that Isle Royale has unique characteristics. Previous studies of how climate change might affect tick-moose interaction have focused on milder winters, which give ticks more time to find hosts while boosting their prospects for successful egg laying by reducing snow cover. If the ground is dry, females survive and lay eggs to start the next generation. Males die, as do females if they fall onto snow-covered ground. The ticks feed on their hosts’ blood through winter, then detach and reproduce. Larvae crawl up forest and meadow plants and wait for hosts - preferably members of the deer family, which includes moose - to brush by so they can latch on.ĭeer do better than moose at grooming themselves to get rid of the pests, perhaps because of evolutionary differences, the paper said. Winter tick life cycles begin in June as each female lays several thousand eggs in soil.
The researchers developed models with those figures, plus temperature and snowfall data and other information, to draw conclusions about climate change’s role. The Michigan Tech team estimated year-to-year levels of tick infestation for hundreds of Isle Royale moose using photographs showing hair loss between 20. Warmer temperatures are expected to help parasites develop faster and survive longer.
Previous studies have predicted wildlife migrating to different areas because of climate change will encounter parasites to which they haven’t developed immunity. “To be a parasite is an easy way to make a living in the natural world.” “But parasites are at least as important as predation,” Vucetich said.