Naturalist's Notes

The Fisher in PA

By Paul Lumia • February 20 2019

By Ben Moyer freelance writer from Farmington, Pa.

The fisher, Pennsylvania’s second-largest member of the weasel family (the river otter is largest), is poorly named. “Mouser” or “squirreler” might be better.

Although fishers prey on diverse food sources, fish are not part of their diet. Small rodents, rabbits, squirrels and carrion make up much of the menu, and fishers are effective predators of porcupines where that prey is available. But biologists who have worked to re-establish the fisher, once extinct in Pennsylvania, concede it will eat almost any wild creature that doesn’t eat it first.

“In fishers, we’ve seen the most diverse diet, including each other, of all forest predators; there’s nothing they won’t eat,” said Matt Lovallo, wildlife biologist in the Pennsylvania Game Commission’s Game Mammals Section. “With some food items like deer, whether it’s predation or scavenging, we don’t know. We do understand that hunters have an intuitive concern about turkeys because fishers are skilled tree climbers, but birds are very limited among the food items we’ve analyzed.”

The name fisher has roots in the older French word “fichet,” which applied to the polecat, a European weasel. Known to scientists as Martes pennanti, fishers are weasel-like in appearance but larger, cloaked in dark brown to black fur, sometimes brindled with white or silver. Big males can exceed 4 feet from snout to tail tip with the heavily furred tail accounting for about a third of the total length. The sharply triangular head is topped with short rounded ears. Adult males generally range between 9 to 12 pounds, with the largest specimens nearly doubling that weight. Females are smaller.

Fishers are forest-dependent and currently range all across Canada’s forest belt, but their original distribution embraced the Great Lakes and extended southward along the Rocky and Appalachian mountain chains. As native Appalachian and Midwestern forests were cleared in the 19th century, fishers disappeared from the region. But as second-growth woodland reclaimed much of the landscape, biologists in Pennsylvania, West Virginia, New York, Michigan and Wisconsin sought to re-establish fishers in those states.

The Pennsylvania Game Commission’s Fisher Management Plan states that West Virginia released fishers captured in New Hampshire as early as 1969. New York followed in the 1980s by re-locating fishers from a remnant Adirondack population to other forested tracts. Most significantly, between 1994 and 1998, Game Commission biologists working cooperatively with Frostburg University released 190 fishers at six heavily forested sites across northern Pennsylvania. Fishers have been sighted, crushed on highways and caught accidentally in traps with increasing frequency ever since.

“Fisher reintroductions have been a success across the Northeast and Midwest, maybe at a quicker rate than we expected,” Lovallo said. “Although we released fishers in northern Pennsylvania, and they’re doing well, we believe the growing population in southwestern counties is a result of range expansion from West Virginia.”

Biologists know that fisher populations are growing and spreading within the state because they monitor legal trapping harvests, survey trappers to track incidental fisher captures and document road-kills.

The Fisher Management Plan reports that between 2001 and 2008 the number of fishers trapped incidentally rose from one to 105. The Game Commission’s Wildlife Management Unit 2C comprising mountainous Somerset, Fayette, Westmoreland, Indiana and Cambria counties accounted for nearly half of the 2008 total.

“Since we wrote that plan in 2008 the number of incidental captures has climbed to over 1,000

Ben Moyer is a freelance writer from Farmington, Pa.

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