Yes, fishers are indeed present in Michigan, representing a successful conservation story for one of the state’s native predatory mammals. This weasel-like creature, Pekania pennanti, is a member of the Mustelidae family, which also includes otters and minks. Fishers were once extirpated from Michigan due to deforestation and unregulated trapping. They have since made a notable return to the state’s northern forests, a direct result of reintroduction efforts and careful management by wildlife officials.
Identifying the Fisher
The fisher is a medium-sized mammal with a long, slender body, short legs, and a notably bushy tail that can add up to 17 inches to its total length. Adult males typically weigh between 8 to 12 pounds, though the largest recorded males can approach 20 pounds, making them substantially larger than their close relative, the American marten.
Their coat is generally a deep, dark brown or black, often appearing glossier and denser in the winter months. Silver or hoary-gold guard hairs may be visible on the head and shoulders, providing a contrast to the darker body fur. The fisher is a terrestrial and agile arboreal animal, possessing the ability to rotate its hind ankles nearly 180 degrees, allowing it to descend trees head-first.
Geographic Distribution in Michigan
Fishers were historically found throughout both the Upper and Lower Peninsulas of Michigan, but they vanished from the state by 1936 due to habitat loss and over-harvesting. The species was reintroduced to the Upper Peninsula (UP) beginning in the 1960s, with restocking efforts focused on areas like the Ottawa National Forest. These initial translocations used animals sourced from Canada to establish a new, self-sustaining population in the UP.
The Upper Peninsula remains the primary stronghold for the fisher population, where they have colonized most available territory. The species has begun to expand its range southward, and its presence in the northern Lower Peninsula (LP) was confirmed in Presque Isle County in 2013. Fishers favor habitats characterized by dense, mixed coniferous and deciduous forests, especially those with significant overhead cover and ample ground litter.
Life and Diet of the Fisher
As solitary predators, fishers occupy a unique ecological niche, primarily hunting on the forest floor and occasionally pursuing prey into the trees. Their diet is highly varied, classifying them as generalist predators that consume small- to medium-sized mammals, including snowshoe hares, mice, squirrels, and birds. They also scavenge on carrion, such as deer carcasses found during the winter.
The fisher is known for its specialized ability to prey on the North American porcupine, a feat few other mammals attempt. The fisher employs a strategy of repeated, quick attacks to the porcupine’s unquilled face, eventually subduing the animal without being seriously injured by the quills. This predatory skill means that fishers can play a regulatory role in porcupine populations within their range.
Reproduction involves a unique biological mechanism known as delayed implantation, resulting in a gestation cycle of approximately 11 to 12 months. Mating typically occurs in late winter or early spring, but the fertilized embryo does not implant in the uterine wall until the following winter. Females give birth to a litter of one to five young the next spring, spending nearly their entire adult lives either pregnant or nursing.
Fisher Population Management
The Department of Natural Resources (DNR) manages the fisher population in Michigan to maintain a healthy balance within the ecosystem. The species has recovered sufficiently from its extirpated status to be classified as a regulated furbearer. This recovered status allows for a limited, controlled trapping season, which helps manage population density.
Trapping seasons for fishers are established only in the Upper Peninsula and require trappers to obtain kill tags and a fur harvester license. The DNR monitors the population by requiring trappers to submit the entire skulls of harvested fishers. Wildlife biologists use these skulls to determine the animal’s age, which provides valuable data for population modeling and informs future management policies.