Weasels belong to the Mustelidae Family, and there are six members of this family living here in NYS. Photo courtesy of Wikipedia.org

Weasels belong to the Mustelidae Family, and there are six members of this family living here in New York state. Weasels possess amazing morphological characteristics that are unique to mustelids. They have elongated necks to enable them to carry large prey. Their legs are short and powerful, enabling them to leap up to 10 times their body length. The bite of the weasel is pound-for-pound one of the most powerful bites in the animal kingdom, so powerful that the lower jaw has to lock into the skull to provide support for its terrible strength. The vertebral column is longer in weasels then in most other mammals, which provides sort of a spring-like force and enables them to take down prey many times bigger than other carnivores the same size. They also have larger-than-average brains in comparison to body mass. The weasel species living in NYS are the river otter, mink, American pine marten, fisher, ermine (short-tailed weasel), and the long-tailed weasel.

River otter populations were decimated in the early 20th century due to unregulated trapping, habitat loss and water pollution. As they primarily eat fish, they were disproportionately impacted by DDTs, PCBs and other pollutants due to “bio-magnification.” Bio-magnification refers to an accumulation of toxins in the food chain. Small aquatic invertebrates consume these toxins initially, which are then consumed by small fish, which are then consumed by larger fish, etc., with these substances becoming increasingly concentrated at each step. The predators at the top of that chain receives the most concentrated doses of these toxins, and river otters are at the top of theirs. Extirpated from the western part of NYS until the 1990s, they recently began to make a slow comeback due to anti-pollution measures and programs such as the NYSDEC’s “River Otter Restoration” project, which captured live, healthy otters from eastern NYS and released them across various sites in western NYS. It was largely a success, and they have been increasingly spotted throughout the region. At upwards of 30 pounds, they are the largest weasel in New York. The fisher is the second largest weasel in our region.

Mink, American pine marten, and fisher are three easily confused species, but if one gives close consideration to the habitat they prefer, as well as their size and geographic range, they should be fairly easy to identify. Mink tend to have a darker (chocolate brown to black) coloration than others and live near rivers and lakes, as well as ponds and marshes. They almost exclusively prey upon the muskrat but will eat other small rodents, birds, and amphibians given the opportunity. Martens are close to the same size as minks but differ greatly in the habitat they prefer. The mink prefers marshy wet areas, while the marten prefers coniferous forests to hunt their favorite prey, the flying squirrel. They will also hunt smaller rodents, such as rabbits and mice, and will also eat birds and eggs, and sometimes even carrion and berries. Fishers live in mature forests and prey heavily on porcupines. Their specialization on porcupines is an impressive feat, as porcupines are armed with quills and outweigh the fisher by more than ten pounds on average. While the fisher is very close in coloration to the martin, it is much larger. Just to make identification even easier for locals, martens do not live in Chautauqua County. Fisher have also seen an increase in populations in recent years, another testament to the value of environmental conservation regulations.

The other two members of the weasel family living in NYS are among the smallest carnivores in the country, along with bats and shrews. Both the long-tailed weasel and the ermine, or short-tailed weasel, weigh in at around a half a pound. Long-tailed weasels are often twice the size of ermine. As small as these predators are, they are still able to tackle prey much larger than them. Both have similar coats (brown on top with white undersides) that turn white during the winter months. This color change aids in winter identification. If you see a weasel-like critter galloping around the wilderness in winter and it has white fur, it is definitely not a mink, fisher, or marten.

These unique animals are often hard to find, as they are natural slinkers and sneaks. This is partially due to their high metabolism and need for frequent meals (they are always hunting). It is also partially due to their having a preponderance of enemies in the food chain. Owls, hawks, and fox will all predate on weasels. However, given time and patience, they can be spotted in the wild. A mink was recently spotted at CWC’s Cassadaga Creek Preserve in the Town of Stockton, one of our preserves that is well known for wildlife viewing opportunities. For more information on weasels or the natural history of our local wildlife, contact Jonathan Townsend, CWC Conservation Lands Manager.

The Chautauqua Watershed Conservancy is a local not-for-profit organization that is dedicated to preserving and enhancing the water quality, scenic beauty and ecological health of the lakes, streams, wetlands and watersheds of the Chautauqua region. For more information, call 664-2166 or visit www.chautauquawatershed.org or www.facebook.com/chautauquawatershed.