Between 1999 and 2011, researchers in northern Maine radio-collared eighty-five Canada lynx and documented sixty-five deaths. Predation was the leading cause. Fourteen of those kills were attributed to fishers. You read that right, an animal that can weigh as little as eight pounds killing a cat that can weigh over twenty-five, the same cat that we recently wrote about killing mountain goats. It was the first time fisher predation on lynx had ever been documented anywhere in the world. It was not a fluke. It was a pattern.
The study was led by Scott McLellan, assistant regional wildlife biologist with the Maine Department of Inland Fisheries and Wildlife, and published in the Journal of Wildlife Management in 2018. The research began as a status assessment of Maine's lynx population, a federally threatened species whose numbers in the Lower 48 were not well understood. Nobody expected the primary finding to be that the leading predator of the lynx was a mustelid most people could not pick out of a lineup.
A fisher is not a small animal. A large male can weigh thirteen pounds and stretch over three feet from nose to tail. It is the second largest weasel in North America after the wolverine. But a Canada lynx weighs eighteen to thirty pounds, stands taller, has longer legs, and is built to run down snowshoe hares through powder snow. The size gap is real. The lynx should dominate every encounter.
In the forests of northern Maine, the opposite happened fourteen times in twelve years.
The researchers never witnessed an attack. They reconstructed them from the evidence. When a radio collar sent a mortality signal, the team tracked it to the location and worked the scene the way a forensic investigator works a homicide. They searched for the body, examined the neck and skull for bite marks, measured the intercanine width of the punctures to identify the predator, and read the tracks in the snow to determine what had happened before the kill.
The snow told the story every time. Fisher tracks connected with lynx tracks. The fisher had picked up the cat's trail and followed it. In multiple cases, the tracks led directly to a lynx bed where the cat had been lying down, resting or waiting out a snow squall. The fisher attacked the neck and held on.
McLellan told National Geographic: they just buckle on. Drag marks led away from the kill site to a cache location where the fisher had stored the body for later feeding. In one case, a fisher was found inside a tree cavity with lynx remains. In another, a radio-collared female and her uncollared kitten were both found cached at the same site. The fisher had killed the mother and the kitten.
In some attacks, the trauma to the neck was so extensive that researchers could not obtain accurate intercanine measurements because of the amount of repeated biting. The fisher had not delivered a single killing bite and walked away. It had stayed on the throat and kept working until there was nothing left to work on.
McLellan called the species a ball of fury. He said a fisher has no boundaries in the size of animal it is willing to attack. He was not overstating it.
The lynx is not the only predator the fisher kills. There are records of fishers killing fox, mink, otters, and raccoons in direct confrontation. Where fisher populations are dense, marten populations collapse because fishers hunt and kill them in the trees and on the ground. Bobcats, which fall in a similar weight range as lynx, are equally vulnerable.
The fisher is not always ambushing out of desperation. It presses confrontations against larger animals and wins the nerve contest because nothing in the weasel family has ever understood the concept of backing down.
McLellan told National Geographic he was unsure whether fishers take on coyotes but said it was possible. If a fisher can get a hold of the neck of an animal, he said, they are willing to hold on.
The hare cycle is the trigger that puts the fisher and the lynx in the same room. Canada lynx are snowshoe hare specialists. When hares are abundant, lynx are well-fed, strong, and operating in deep-snow habitat where fishers are less effective. When the hare population crashes, lynx weaken. Their bone marrow shifts from white and waxy to red and gelatinous, a diagnostic marker of malnutrition. A 2026 study published in Scientific Reports confirmed that when hare populations drop, habitat overlap between lynx and fishers increases. Both species contract into the same remaining cover.
Several of the lynx killed by fishers in the Maine study showed poor body condition at necropsy. A malnourished lynx bedded down in a snow squall is not the same animal as a healthy lynx running hares through powder. The fisher reads the difference in the tracks before it ever reaches the bed.
Fishers are not invulnerable though. Coyotes kill them. Black bears kill them. Great horned owls take juveniles. Wolves have killed fishers caught in the open on frozen lakes. The fisher exists in the middle of the food web, not at the top. But nothing else in the northeastern forest specifically tracks, ambushes, and kills an animal twice its size with the consistency that the fisher brings to lynx.
Not even the wolverine targets a specific larger predator with this kind of consistency. The wolverine is bigger, stronger, and operates on a larger stage, but it does not track lynx to their beds and kill them in their sleep as a matter of routine. The fisher does. If you put a fisher’s aggression and killing style inside a body the size of a wolverine, even wolves might end up on the menu. Luckily, that animal exists only in imagination.
That fourteen lynx in northern Maine were not dealing with imagination.
Source: McLellan et al. (2018), Journal of Wildlife Management. Maine Department of Inland Fisheries and Wildlife. National Geographic, January 2022. Scientific Reports, February 2026. National Trappers Association.
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