Deer in Spring Landscape

Maryland's Mustelids

Maryland's largest family of furbearers is also one of its least understood. Mustelids are a group of mammals that possess two anal glands, which exude or forcefully project a volatile, stinky substance that is used as a territorial marker or as a defensive response. Few people probably realize that the American martin (Martes americana), ermine (Mustela erminea), fisher (Martes pennanti), least weasel (Mustela nivalis), long-tailed weasel (Mustela frenata), mink (Mustela vison), and river otter (Lutra canadensis) are closely related and use their stinky scents to their advantage.

Although fairly elusive and rarely seen, mustelids are widely distributed and fulfill extremely important roles in local ecosystems. All mustelids are predators and feed almost exclusively on other animals. Many mustelids help control rodent populations.

In addition to their ecological value, mustelids are also a renewable economic resource for many of Maryland’s citizens. Furbearers can be loosely defined as mammalian species that can be legally harvested for their pelts. These pelts are then normally sold to be fashioned into fur garments or other utilitarian items. Of the seven species of mustelids that currently occur in Maryland, four are legally defined as furbearers and are subject to regulated harvest. The following information provides a description, status and distribution of the four legally harvested mustelid species.

(Martes pennanti)

Photo of Fisher by Nature PhotographyFishers have elongated bodies resembling a large weasel with a large bushy tail. They range in size from 29-48 in., and weigh 4-13 lbs. Some large males can get up to 20 lbs. Males are typically at least 20% larger than females. Depending on the time of the year and sex of the animal, fisher pelts can range from dark reddish brown to a grizzled black. This grizzled appearance results from tricolored guard hairs. Guard hairs are long, protective hairs found in the coats of mammals. Males tend to be more grizzled than females, and females possess longer, silkier fur.

Fisher diets include squirrels, rabbits, small mammals, birds and, surprisingly, porcupines (Erethizon dorsatum). Fishers will flip porcupines over to eat them. Fisher are arboreal (spend time in trees), therefore, they prefer areas with lots of tree cover. However, fishers can sometimes be found in or in close association to mixed forests, small forest openings and farm fields.

Historically, fisher populations in eastern North America extended from Canada through the Northeastern states and throughout the Appalachian mountains as far south as Tennessee. By the early 1900's the fisher had been extirpated from Maryland and other central and southern Appalachian states. During 1969, the West Virginia Division of Wildlife Resources initiated a fisher reintroduction project. Twenty three fishers were obtained from New Hampshire and were released at 2 sites in West Virginia. Fifteen animals were released on Canaan Mountain in Tucker County, and the remaining 8 animals were released near Cranberry Glades in Pocahontas County. By 1972, West Virginia’s introduced fisher population had expanded sufficiently to support a legal harvest season in West Virginia. In Maryland, fishers are primarily found in the western region, particularly in areas with old growth forests.

Long-Tailed Weasel
(Mustela frenata)

Long-tailed weasels are relatively small animals. They have slender, elongated bodies. Body sizes range from 11-17in long. Males tend to be significantly larger than females. The overall color of the long-tailed weasel is brown with a yellowish white neck and underside. In the Northern United States, long-tailed weasel molt in the fall and their fur becomes totally white. The weasels remain that color until they molt again in the spring, and their fur returns to brown. In the mid-Atlantic region (including Maryland) and farther south, weasels remain brown throughout the year.

Weasel feed extensively on mice and other small mammals, but will also eat birds, rabbits and amphibians when available. Long-tailed weasel can live in a fairly broad range of habitat types. In Maryland, long-tailed weasel habitat includes marshland, woodlands, intermittent grasslands and rocky outcrops. Long-tailed weasels are sporadically distributed throughout the state.

(Mustela vison)

Photo of Mink by Robert Barber/Painet, Inc.Mink are small cylinder shaped animals ranging from approximately 19-30 in., and 1.5 - 4 lbs. Males tend to be 1.5 times larger than females. Their fur is short and glossy and can vary from light brown to almost black. They also possess white chin and/or chest patches that vary in size from individual to individual.

Mink are semi-aquatic and utilize all types of quality wetlands within their range. They frequent suitable bodies of water ranging from fresh and brackish marshes to farm ponds and fast moving trout streams. Dependent on seasonal availability, mink prey upon birds, small mammals, fish, amphibians, and crustaceans.

Mink are common from Garrett County eastward to the western shore of the Chesapeake Bay and are found infrequently on some of the larger islands in the Bay proper. For unknown reasons, mink are absent from the Eastern shore and many coastal regions in the eastern United States.

River Otter
(Lutra canadensis)

Photo of River Otter by John WhiteRiver otter display typical weasel- like features. Their bodies are relatively long, streamlined and include an elongated flattened tail. Their legs are short and feet are webbed. The total length of river otters varies from 35 to 55 inches and weights range from 12 to 35 lbs. River otters have short, dense and glossy fur that comes in various shades of brown. River otter feed predominantly on fish, but will also feed on crustaceans, mollusks, amphibians, reptiles and other small animals when locally abundant. River otter are semi-aquatic and utilize most healthy wetland systems. In Maryland, they occupy wetlands ranging from trout streams to tidal marshes.

Prior to 1990, otter were distributed at varying densities throughout the state with the exception of Garrett and Allegany and western Washington counties. At that time, otter were absent from this 3 county region. During the early to mid 1990's the Department of Natural Resources initiated a project to reintroduce otter to the mountainous portion of western Maryland.

Historically, otter had been extirpated from this region in the 1800's. Otter were trapped from abundant populations on the eastern shore of Maryland by Departmental personnel and were transported to western release sites. Initial project efforts focused on the Youghiogheny river drainage in Garrett County. Subsequent releases also occurred in smaller drainages within the county. After self-sustaining, viable populations were restored in Garrett County, efforts were then shifted to Allegany County.

As a result of successful reintroduction efforts, otter are now distributed statewide. Highest population densities occur in the coastal plain adjacent to the Chesapeake Bay. As you proceed westward from the Bay, population densities decrease incrementally until the reach their lowest level in Allegany County. Otter populations in Garrett County have increased dramatically and can now be considered common.