Northern Short-tailed Shrew - Blarina brevicauda
( Say, 1823 )

 

 

Northern Short-tailed Shrew Photo
No Map Available North America
Northern Short-tailed Shrew Photo No Map Available North America

Subspecies:
Est. World Population:

CITES Status: NOT LISTED
IUCN Status: NOT LISTED
U.S. ESA Status: NOT LISTED

Body Length: 3 - 4 inches
Tail Length: ½ - 1½ inches
Shoulder Height:
Weight:

Top Speed:
Jumping Ability: (Horizontal)

Life Span: 3 years in the Wild
Life Span: 3 years in Captivity

Sexual Maturity: 6 weeks (Females)
Sexual Maturity: 12 weeks (Males)
Litter Size: 3 - 10
Gestation Period: 21 - 22 days

Identification:
Head and body length is 3-4 inches, tail length is ½-1½ inches. Males are slightly larger than females, especially in the skulls. The fur is velvety and soft, and the color almost uniformly slate gray, with the underparts being only slightly paler. Summer pelage is a shade paler than winter.

Blarina brevicauda is a robust-looking shrew, nearly the size of a meadow mouse; the snout is shorter and heavier than that of other shrews, the tail is short, the eyes small, and the ears are almost completely hidden by the fur.

Habitat:
Short-tailed shrews are found in nearly all terrestrial habitats. However, their populations are most dense in damp brushy woodlands, bushy bogs and marshes, and weedy and bushy borders of fields. These shrews are also common in cultivated fields, in flower and vegetable gardens, fence rows, and beside country roads. In the winter, they often retreat into barns, cellars and sheds. They need only sufficient vegetation to provide cover. They are slow to rehabit areas of forest burns. Short-tailed shrews construct elaborate runways under leaves, dirt, and snow and construct their nests in tunnels or under logs and rocks.

Biomes: temperate forest & rainforest, temperate grassland

Range:
Nearctic: Short-tailed shrews inhabit most of North America from southern Saskatchewan and Nova Scotia to central Nebraska and Georgia.

Life Cycle:
Elaborate mating nests, 6-10 inches long by 6 inches wide, are built out of shredded grass or leaves and placed in tunnels or under logs and rocks. The breeding season extends from early spring to early fall (March-September), although some scattered reproductive activity may occur throughout the entire year. Females may have up to 3 litters per year, although 2 is more usual. Gestation is 21-22 days and litter size is 3-10, although 5-7 pups is most common. The young leave the nest when 18-20 days old and are weaned several days later. Females reach sexual maturity at 6 weeks, while males mature at 12 weeks. The life span can be as long as 3 years, but it is usually much more brief.

Food & Hunting:
Short-tailed shrews are voracious eaters and must feed frequently, commonly in the early and late afternoon. It is estimated that they consume and metabolize as much as three times their weight in food per day. The diet of Blarina brevicauda consists mainly of invertebrates, small vertebrates, and plant material. B. brevicauda stores food for winter, including snails and beetles, and in captivity puts nutmeats, sunflower seeds, and other edibles into storage.

The submaxillary salivary glands of Blarina brevicauda produce a toxic material which is effective in subduing its prey. This enables it to prey upon animals much larger than itself, including salamanders, frogs, snakes, mice, birds, and other shrews.

Behaviour:
Short-tailed shrews are active year round, both day and night (although they are more nocturnal than diurnal). These shrews are the most fossorial of American shrews and are effective in tunneling through leaves, plant debris, and snow with their strong paws and cartilaginous snouts. They construct elaborate runways and nests but have also been known to use the tunnels of mice and moles. Although most of their time is spent on or under the ground, short-tailed shrews are also effective climbers and have been observed climbing nearly 6½ feet up a tree trunk to obtain suet from a bird feeder.

Blarina brevicauda is not a sociable or gregarious mammal. In captivity,short-tailed shrews have been observed to live together peacefully if enough space is provided, but in the wild, the shrews are solitary and territorial. Territory size and stability are determined by prey density and tend to overlap slightly between members of opposite sexes during the breeding season. Shrews mark their territories with scent and will threaten and physically drive away any intruders. Blarina brevicauda utters a variety of sounds (chirps, buzzes, twitters) in its aggressive interactions with other individuals, and a clicking sound is used during courtship.

Conservation:
Blarina brevicauda is common through much of its range, especially in the areas surrounding the Great Lakes. As with many small mammals, its populations undergoes frequent fluctuations, the causes and effects of which are not well understood.

Other Details:
Similar to other shrews, Blarina brevicauda has a highly developed sense of touch, particularly in the snout and vibrissae, and relies very little on its vision, which barely enables it to distinguish light from dark.

Major predators of the shrew include raptors such as hawks and owls, shrikes, snakes, and occasionally pickerel, trout and sunfish when shrews venture into the water. However, many predators discard the short-tailed shrew because of the foul odor arising from a pair of glands located on its sides near the flanks.

Due to its insectivorous nature and ravenous appetite, Blarina brevicauda often serves as an important check on insect crop pests, especially the larch sawfly. It also destroys snails and mice that damage crops and are pests to humans. The poison secreted from the submaxillary glands of Blarina brevicauda can cause pain that lasts for several days in a human who is bitten. Bites from Blarina brevicauda are extremely rare, however, and have only been suffered by humans who have attempted to handle the shrew.

References:
Nowak, Ronald. Walker's Mammals Of The World. Baltimore: Johns Hopkins University Press, 1999

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