Least Weasel (Mustela nivalis)

County List:

Rule:

Mixed Forested/Nonforested or Nonforested Landscapes

      Grass
      or Small Grains/Forage Crops
      or Fields/Pasture
      or Sedge Meadow

Habitat List:

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Literature:

It is a habitat generalist, occurring in fencerows, old fields, pastures, riparian edges, open woodlots, and to a lesser extent, mature forests.

Mouse-sized mammals are the usual prey and include red-backed voles, southern bog lemmings, white-footed mice, masked shrews, and many others. Birds and amphibians, and insects contribute to the diet.

Habitat Preferences: The least weasel occurs in a variety of environments in southern Michigan, especially in open situations. Apparently the combination of small woodlots, cultivated fields, fallow land, weedy and brushy fence rows, marsh edge, and streamside vegetation is the preferred habitat, with little evidence available that the least weasel uses woodlands extensively. In Ingham County, Heidt captured numerous least weasels in live traps placed in mixed grass, weeds, and shrubs along railroad tracks on the campus of Michigan State University; Golley found this weasel to be an important link in the food chain of an old field community of perennial grasses; and Osterberg photographed a least weasel in a small mammal runway in grass cover. Hatt found least weasels in Oakland County by a small creek, along a drainage ditch, and in a fence row. In residential areas least weasels sometimes become trapped in basement window wells.

Behavior: Least weasel nests are placed in a variety of protective sites either above or below ground. Jackson found dens in creek bank holes and under corn shocks. More than likely, however, burrows are confiscated from meadow voles, eastern moles, thirteen-lined ground squirrels, or other burrowing creatures. The least weasel will widen a passageway to make a nest and then line it with fine grass or hair and feathers from victims.

Key Components of Habitat: Avoids dense forest; most abundant in association with ecotones where prey diversity is greatest.

Management Actions to Enhance or Maintain Habitat Quality: Maintain woodlots in agricultural areas with minimal grazing or disturbance to ensure diversity of understory vegetation and foods; maintain shelterbelts and fencerows for cover and travel corridors; encourage establishment of fruit-producing shrubs and trees.

Habitat: The least weasel has been recorded in a wide variety of habitats. In the Far North it occurs on the tundra and sometimes in coniferous forest and woodlands. Farther south the least weasel tends to occur in more open areas, while the short-tailed and long-tailed weasels are often found in forest and woodland habitats. The least weasel is commonly found in meadows, grasslands, and river bottoms. Gunderson and Beer reported that least weasels in Minnesota used marshes and damp meadows. In a study by Loekmoen and Higgins, least weasels were not selective and were observed in native prairie, wetlands, river bottoms, hayfields, and farmlands. As with the short-tailed weasel, the abundance of small mammals is important in determining the local distribution of least weasels. At the edges of its range the least weasel is normally observed near watercourses or reservoirs, suggesting that dispersal of the species is through riparian habitats and across agricultural land located on floodplains.

Ecology: Habitat selection by M. nivalis is determined by the local distribution of small rodents. Throughout its range, it is found in open forests, farmlands and cultivated fields, grassy fields and meadows, riparian woodlands, hedgerows, alpine meadows and forests, scrub, steppe, and semi-deserts, prairies, and coastal dunes. Deep, dense forests and sandy deserts, which lack food and/or cover, are avoided. On the periphery of its range in North America, M. nivalis is usually observed in riparian habitats, suggesting that dispersal occurs through these habitats and across adjacent agricultural lands. Foraging individuals avoid open spaces, where they are most vulnerable to predation by raptors, and concentrate their activity along protected edges. In farmlands, M. nivalis is generally restricted to hedgerows, fencelines, and piles of cutover brush, whereas in open steppe they remain under long grass. M. nivalis lives year-round at high elevations on low-latitude mountain ranges such as the Caucasus, Alps, Tien Shan, Altai, Atlas, and Appalachians. They are well-adapted to tundra and snowy environments and range above treeline in arctic and alpine areas. Snow presents little obstacle to the distribution, hunting, or movements of M. nivalis.