In the empty winter forests of Maine, small weasel-like animals known as fishers bet against their mortal odds when it comes to food and survival.
New research shows for the first time that these opportunistic predators—not much larger than a big house cat—can and do take down Canadian lynx, which can grow up to double their size. (Related: Fierce, Furry Fishers Are Expanding Their Range—and Bulk.)
“A fisher really doesn’t have any boundaries in the size of the animal it’s willing to attack,” says Scott McLellan, assistant regional wildlife biologist with the Maine Department of Inland Fisheries and Wildlife and the lead author of a study published recently in the Journal of Wildlife Management.
“We know that fishers are very opportunistic,” he says. “They are just a ball of fury.” (Watch: Hear a fisher's scream.)
Scene of the Crime
While researchers never witnessed an attack firsthand, McLellan’s and his coauthors’ “scavenger hunt” for these attacks started with putting radio collars on lynx to track the cats’ movements in Maine from 1999 and 2011. When they suspected that a lynx had met its end, they would track down the location of the collar.
At this point, piecing together the evidence was a little like forensic anthropology at a crime scene. They would try to find the legs and various parts of the cat—especially the neck and head, which could show bite marks as evidence of a fisher kill and rule out the possibility that the weasel just stumbled across a lynx who had recently died.
Lucky for the researchers, many of these attacks happened during the dead of winter and evidence could be seen in the snow.
Researchers found that before the attack happened, they would often see the fisher tracks connect with those of the lynx, indicating the weasels had picked up the cats’ trail.
A Ghost In A Snowstorm
Based on the appearance of the tracks, an attack by a fisher on a lynx would often happen in the middle of a quick snowstorm, which may have worked to the advantage of these vicious little predators. A fisher would attack, often when the cat was bedded down to wait out the snow flurry, going right for the lynx’s neck.
“They just buckle on. They have a pretty powerful grip and they know where to attack,” McLellan says, adding that the fishers would finish the cats off pretty quickly. “There was some struggle certainly, but it didn’t appear to last very long. There were some broken branches, tufts of fur, and claw marks where the lynx was trying to get away.”
Once the lynx were dead, the fun had just begun for the gruesome fishers. The weasels would begin to dismember the fresh lynx carcass and hide pieces in various places, likely since it couldn’t eat the whole 20-to-30-pound body in a single sitting.
“It might drag a leg up into a tree. It might drag a leg into a brush pile or under the snow somewhere,” he says, adding that they would also remove the heads sometimes.
There is evidence, though, that some lynx were not passive prey items, McLellan says. “In some cases we found fisher hair stuck in the mouth of the dead lynx, so there was obviously some effort on the lynx’s part to defend itself,” he says. But he is unsure whether lynx ever beat the fishers in these mortal battles, or whether they sometimes even prey on the weasels.
On the other hand, bobcats—close relatives of lynx—turn the tables on the feisty fishers, according to research by Greta Wengert, cofounder of the Integral Ecology Research Center, a non-profit organization dedicated to the research and conservation of wildlife and their ecosystems.
“Pretty quickly it became evident that bobcats were the main predators, at least on female fishers,” she says, adding that she and other researchers are focusing a lot of attention on Western subspecies of fishers due to ongoing research by the U.S. Fish & Wildlife Service into possibly listing those animals as endangered or threatened.
According to her, the western subspecies of fishers are often a little smaller than their eastern counterparts, which may be enough to tip the scales in favor of the felines. Bobcats are also a little smaller than lynx.
But once again, size can be deceiving.
“Bobcat and felid researchers weren’t completely surprised because [bobcats] are known to be more aggressive—more power pound for pound [than lynx],” Wengert says.
McLellan says that his team found about a dozen examples of fisher predation on lynx in their four township area of Maine over the roughly 12 years of study, and suspected a few more cases. But while these cats certainly meet a grisly end, this interaction doesn’t seem to have any negative population effects on the lynx, whose population has actually been growing over the study period.
The newly discovered interaction speaks to the fact that different animals have different ecological niches, and McLellan would like to learn more about these interactions: “If I had my way, we’d be putting more collars on both fishers and lynx.”
He is unsure whether fishers take on other unruly predators besides lynx in the area, but he says it’s possible they might take out a creature like a coyote.
“If a fisher can get a hold of the neck of an animal, they are willing to hold on for dear life,” he says.