Elusive and often misunderstood, the fisher (Pekania pennanti) is understudied in southern New England. Despite the common misnomer “fisher cat,” this agile member of the mustelid family – which includes badgers, ferrets, and weasels – is neither a cat nor a catcher of fish, but roams forests across North America. Due to its role as a generalist predator, its numbers and behavior can offer researchers insights into ecosystem health.
Tracy Rittenhouse, a wildlife scientist in the College of Agriculture, Health and Natural Resources (CAHNR) is working to monitor these secretive creatures through collar-tracking animals across Connecticut. The project will help researchers gain insights into habitat use, reproduction, and sources of mortality.
“Fishers are in decline in Connecticut, but we aren’t sure of the reasons why,” says Rittenhouse, an associate professor in the Department of Natural Resources and the Environment (NRE). “We need to take a closer look at what is happening to them and ways we can aid in their management. Their numbers also appear to be lower in the western part of the state compared to the eastern, so we want to better understand why that is.”
Fishers are solitary creatures and prey upon many other species. Their presence, or lack thereof, can have a notable impact on other animal populations and the ecosystem in general.
Fishers prefer old growth forests with lots of tree canopy cover. Following a long period of deforestation, population growth, and then reforestation, the fisher returned to Connecticut. The population grew in size for about 20 years but recently has been declining.
NRE undergraduate research technicians, Julio Tozetto ‘25 (CAHNR) and Annalise Cormier ’26 (CAHNR), had the chance to take on important elements of the research, which requires a large team. They were joined by NRE graduate student Rebecca Leloudis and received assistance from the Connecticut Department of Energy and Environmental Protection (CT DEEP) to help Rittenhouse and the team to trap fishers all over the state. With the goal of capturing three or four fishers in 12 areas throughout the state, they have their work cut out for them. Most fishers successfully collared last year were in eastern Connecticut. They are trying again this winter.
“We set and check the traps,” explains Cormier. “Members of the CT DEEP Wildlife Division handle the animals, taking samples, and then collaring them.”
“We use two types of collars: GPS and radio,” says Tozetto. “Males are equipped with the GPS collars and can be tracked by satellite. The females are smaller and need to be tracked using radio telemetry.”
The radio waves have a limited distance, so the student technicians scour the state to pick up the collar signals to determine the female fishers’ locations. Males have a wider range while females are more limited, especially when mothers give birth and nurse their kits. During this period, they den in tree cavities, hollow logs, or even in rock crevices to stay safe from predators, such as bobcats, and protected from extreme weather.
“One possibility for the population decline could be high predation rates,” says Rittenhouse. “If driven into open spaces, fishers might be more vulnerable to coyote or bobcat attacks, for example. If their home range includes roads, vehicles could be an additional source of mortality. The movement data can help us understand where and how corridors or protected areas might be used. Similarly, we can see where the females are denning to try to ensure those areas remain safely accessible.”
Fishers mate in the spring but have developed a special adaptation known as delayed implantation. This allows mating, but the female can decide the timing of the kits. Female fishers settle into dens to give birth in late March in Connecticut. A mother usually gives birth to three to four kits at a time.
With all of this additional tracking data, the research team hopes to give a more accurate picture of the elusive animal and its role in our ecosystem.
“Fishers have this reputation as being insatiable hunters that target domestic pets, but like other species, they are trying to survive, and their behavior shows they prefer not to take risks, especially near humans, or venture into exposed areas,” Rittenhouse says. “As we continue to learn more about where they go, when they move, and what they need, we will gain better insights into how fishers are adapting to their changing environment and ensuring the ecosystem works for all.”
Have you seen a fisher within the last two years? Please report the sighting.
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