Northern Short-Tailed Shrew (Blarina brevicauda)

County List:

Rule:

Forested or Nonforested Landscapes

      (Any Forested Upland (Any Size Class))
      or (Any Forested Lowland (Any Size Class))
      or Grass
      or Upland Brush
      or Savanna
      or Fields/Pasture
      or Residential
      or Sedge Meadow
   containing:
      Dead Down Woody Debris

Habitat List:

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Literature:

It occurs in a variety of disturbed and undisturbed habitats - grasslands, old fields, fencerows, and marsh borders, as well as deciduous and coniferous forests. This large shrew prefers moist environments with excessive herbaceous cover or a thick layer of litter; it is, for example, less likely to live in a heavily grazed pasture or plowed field than in a mature deciduous woodlot.

Although it eats subterranean fungi and seeds in small amounts, the short-tailed shrew is mostly carnivorous. It preys heavily upon insects and earthworms but also takes centipedes, millipedes, spiders, slugs, and snails. The short-tailed shrew includes vertebrates in its diet more often than other shrews and readily attacks smaller shrews, voles, mice, salamanders, and snakes.

Habitat: Both timbered and fairly open habitats: deciduous, mixed, and less often in coniferous forests with moist loose humus; especially common along banks of streams and meadows with tall rank grasses or sedges, brush piles and stone walls. Avoids dry warm sites. Favored grass-sedge marsh and willow-alder shrub zone in Manitoba.

Special Habitat Requirements: Low vegetation, loose leaf litter, high humidity.

Habitat Preferences: The short-tailed shrew is at home under varied living conditions in Michigan - from swamps and bogs in moist lowlands to dry uplands and even on sand dunes. Its ability to survive in vacant lots, city parks, and right-of-ways of streets and railroads makes this shrew a common urban and suburban resident. However, moist, litter-strewn forested areas are considered prime living places for this short-tailed shrew. Normally, it does not frequent areas completely devoid of vegetation, unless snow-covered. Shocked grain left in fields and surrounded by cleared stubble can serve as protective winter cover for the shrews.

Density and Movements: The meadow vole will out-number the short-tailed shrew, as well as the masked shrew, in many open grassy and marshy sites, but in brushy and forested habitats, the two shrews will be far more abundant. Haveman estimated shrew populations at 19 per acre in mature hardwoods forest, seven per acre in spruce swamp, and five per acre in bog environment.

Surface trails and underground tunnels lead into these nests which can be found in grass cover on the surface of the ground, under logs, in dead stumps, under debris, or as much as 1 foot underground.

Food Habits: The short-tailed shrew feeds mostly on insects, other invertebrates, and small vertebrates. Some of the many foods eaten are crickets, moths and their larvae, flies, ground-living bees and wasps, beetles and their larvae, spiders, millipedes, centipedes, sowbugs, snails, slugs, earthworms, and such vertebrates as salamanders, garter snakes, small birds, mice, other shrews, pine seeds, and even starchy vegetable material.

Ecology: Miller and Getz calculated that short-tailed shrews have broad habitat requirements but were most common in areas with more than 50% herbaceous cover. Conversely, Dueser and Shugart iterated that short-tailed shrews in eastern Tennessee have a narrow, somewhat specialized niche. Getz found that food was the limiting factor in wooded habitats; type of vegetation, cover, temperature, and moisture had little effect on local distribution, although shrews avoided areas with little cover and with extremes of temperature and moisture. Pruitt suggested that deep litter protected shrews in hardwood forest from temperature and moisture extremes. B. brevicauda was the most ubiquitous and abundant of five species of mammals studied in farmstead shelterbelts in southern Minnesota, based on captures in both wooded and unwooded habitats. B. brevicauda moved between shelterbelts more often than other species studied. In Iowa, B. brevicauda was associated with big bluestem, Andropogon gerardi; in Quebec, they occurred primarily in mature deciduous-coniferous forest and secondarily in fields of tall grasses and sedges. Sinclair et al. found short-tailed shrews associated with stone walls in relatively dry situations in eastern deciduous forest; they suggested that humidity might be higher near the stone walls than in adjacent microhabitats, thereby enabling short-tailed shrews to inhabit otherwise dry areas. In eastern Tennessee, Blarina consistently occupied areas of high stump and log density, hard ground, few shrubs, and dense overstory, and they fed on larval insects found in the stumps and logs.

After a timbered area is clear-cut, populations of shrews decline abruptly. Powerline corridors seem to be a dispersal barrier for short-tailed shrews.

Northern short-tailed shrews were highest in the oldest stands sampled.

Kirkland showed increased soricid numbers on recent clearcuts relative to uncut stands in five of eight surveys in deciduous forest types in the Central and Northern Appalachians. Since we found smoky shrews and northern short-tailed shrew abundances to be lowest in 15-year-old stands, increases in shrew numbers in the initial years following clearcutting in the southern Appalachians may be brief. DeGraaf et al. reported little overall significant difference in the numbers of northern short-tailed shrews, pygmy shrews, and masked shrews between pole-timber stands and sawtimber stands in northern hardwoods communities in New Hampshire. Differences in relative abundances of smoky shrews and northern short-tailed shrews on regenerating clearcuts and mid-aged stands are probably not biologically meaningful to the conservation status of soricids in cove hardwood habitats in the southern Appalachians. For example, relative abundance of smoky shrews and northern short-tailed shrews in cove hardwoods of all ages exceeds most other habitat types in the region, including mature or older mixed oak communities found on dry slopes and ridges. However, the differences in abundance of smoky shrews and northern short-tailed shrews among stand ages may indicate that conditions in younger cove hardwood stands only partially approximate conditions in older cove stands.

Blarina brevicauda has been reported to prefer hardwoods in the central and southern Appalachian Mountains. It has been reported as rare in eastern Canada and absent in Maine softwoods. In our study, B. brevicauda occurred in both softwood types (balsam fir; red spruce-balsam fir) at approximately half its abundance in either hardwood type (northern hardwood, red maple). Most hardwoods may be preferred habitats within its distribution.

Blarina brevicauda is known to select areas with fallen logs, slash, rock and other debris; forest type may be important only as a modifier of microclimate. In southeastern Michigan, Blarina occurred only in those habitats in which burrow air was always saturated with water vapor. Hamilton noted B. brevicauda to be most abundant in habitats with heavy leaf mold; this substrate is more prevalent in hardwoods than in conifer stands. Perhaps humidity was higher in the hardwoods as a result of their denser understory and ground cover.