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The greatest number of winter ticks that Peter J. Pekins found on a moose was about 100,000. But this moose calf was already dead, probably anemia, which develops when many ticks drain the blood of a momentum. This was probably a low estimate because some of the ticks had already become detached.
"It's about the same picture you can imagine on a dead animal," said Dr. Pekins, professor of natural resources and the environment at the University of New Hampshire. (A warning: the images below are, in reality, grody.)
Between 2014 and 2016, Mr. Pekins counted ticks on moose calves at two locations in New Hampshire and Maine. He wanted to know how moose were going, given that climate change was delaying the arrival of snow during the New England winters.
The heat that lasts longer gives a boost to the ticks as they throw themselves on moose, their favorite host, in the fall. They then feed in winter and jump in the spring to lay their eggs.
The exploits of Dr. Pekins and his colleagues on the moose trail have been published last month in the Canadian Journal of Zoology. They argued that three consecutive years of tick outbreaks "no doubt reflected a host-parasite relationship strongly influenced by climate change on the southern outskirts of the moose habitat".
Although a large number of ticks, true blood sucking parasites, are not attractive to adult moose, they are particularly harmful to moose calves, who may die from assault.
With the help of a team that pulls nets from helicopters to catch and tag calves with radio collars (process that takes about 15 minutes for moose and avoids the "bugs"). drug use), Dr. Pekins was able to follow 179 moose calves. The average number of ticks he found on them was 47,371.
"Something over 35,000 is a problem for a calf moose," he said. During the study period, 125 calves died, 70% of which were followed.
In some respects, moose are victims of their own success.
"Maine and New Hampshire had less than 50 moose in the 1970s," said Dr. Pekins. But their numbers have multiplied several times since then, thanks to the improvement in available habitat and the lack of predators such as the wolf.
As a result, Maine now has between 60,000 and 70,000 moose; New Hampshire had no less than 8,000 or 9,000 in the early 2000s, although their numbers now approach 5,000. And it is the abundance of moose that allows ticks to survive.
"You need a lot of moose in the landscape to have a lot of parasites," said Dr. Pekins. "It's the host-parasite relationship."
This relationship was more or less balanced until the changing climate tipped the scales in favor of ticks. In the long term, Mr. Pekins does not expect moose to die completely, but there will be less.
Ticks do not want the moose to die completely either. "The parasite does not want to kill his host – it's a bad move," said Dr. Pekins. "Because the parasite loses the game."
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