Fishers (a large member of the weasel family that lives in forested areas) were nearly extirpated from New York State in the 1930s, due mostly to unregulated trapping and habitat loss. In recent years, observations from hunters, trappers, landowners, and the general public suggest that fisher populations are expanding into central and western New York from outside of their established range in the Taconic, Catskill, and Adirondack mountains. In addition, emigration of fishers into New York from Pennsylvania has likely fostered population growth in the southern tier of the state. The fisher is an important and popular furbearer for trappers in eastern New York, where seasons have been open since the 1950s. In recent years, annual harvests have averaged close to 2,000 fishers.
Wildlife managers often rely upon harvest data to track wildlife populations, but with the expanding fisher population in central and western New York where the season is closed, this tool is not available. To better document the expansion of fishers into central and western New York, we deployed about 600 baited “camera traps” across 22 Wildlife Management Units (WMUs) in winter 2013 and 2014. The number of WMUs surveyed was expanded from 2013 to 2014 to resurvey sites sampled the previous winter, to assess previously unsurveyed WMUs, and to survey WMUs currently open to trapping for comparison to WMUs closed to trapping.
When a fisher visited the bait (a large piece of beaver meat attached to a tree about 4 feet above ground), a motion-activated trail camera captured an image of the animal. At the same time, strategically-placed wire brushes around the bait collected a hair sample. The photos allowed us to assess “occupancy”—the probability that fishers live in a certain area. The hair samples are used for DNA testing to allow us to identify individual animals and movements between “trap” sites, which in turn, will allow us to estimate population density. We can use occupancy and density estimates to paint an accurate picture of the status of fishers in central and western New York. These data will also be used to develop a management plan for this important furbearer species. The camera-trap surveys will continue in winter 2015, but we are still collecting observations from the public. If you see a fisher anywhere in New York, particularly in portions of central and western New York closed to trapping, please send us the details at: http://www.dec.ny.gov/animals/30770.html.
Camera-trap sites were located in 15 km2 grid cells (based on the average home range of a female fisher) spread across 22 WMUs.
Regulations in red are new this year.
Purple text indicates an important note.