Blarina brevicauda
Short-tailed Shrew
Description:
Total Length 96-130 mm
Tail Length 18-32 mm
Weight 15-30 grams
Short-tailed shrew is the largest shrew in North America. (Boonstra 2002) It has a robust
body with a dense, velvet coat. The dorsal fur is darker brown/gray while the ventral fur
is a lighter gray. The ears and eyes are small easily hidden by the fur. Their snout is
elongated and comes to a point. (Kurta 1995) They have five unicusped teeth in the upper
jaw, second and third incisors, and canine, normal premolar and minute molar. (Jackson
1961) Males display a somewhat sexual dimorphism, being larger than the females.
(Benedict 1999)
Distribution:
Short-tailed shrews range from south eastern Canada and north eastern U.S. south to
Nebraska, Missouri, Kentucky, and Alabama. (Whitaker1996) Short-tailed are abundant
especially in the northern regions and can be found throughout Wisconsin. They live in a
variety of disturbed and undisturbed habitats such as grasslands, old fields, fencerow,
marsh borders as well as deciduous and coniferous forest. They prefer moist
environments with more than 50% herbaceous cover. (Boonstra 2002, Kurta 1995)
Reproduction:
Reproduction can occur year round but mostly takes place March through September,
females giving birth earlier or later in the season. Females can have up to three litters per
year; gestation is 17-22 days. (Whitaker 1996) Average of 4-7 is born weighing less than
one gram. Young leave the nest at about 18-22 days and are weaned by day 25.
Females reach sexual maturity at 6 weeks and males reach sexual maturity at 12 weeks.
(Kurta 1995)
Behavior:
Short-tailed shrews tend to be solitary animals, densities range from 5-30/ha depending
on the vegetation and cover. (Kurta1995) They are the most fossorial of all the shrews,
building underground nests and tunnel systems. Two different nests are created, one for
resting (160mm long, and 203mm wide) and the other for reproduction (150-250mm long
and 100-150 wide). (Merrit 1986) The tunnel system is built with 2-3 exits along with
various tunnels that are used for waste deposits and storage of extra food. (Kurta 1995)
Short-tailed shrews are active for 5 minute bouts which add up to 4 hours each day in the
early morning and 2-3 hours after sunset. (Benedict 1999) Because they are food
hoarders and utilize higher energy sources they are able to stay active all year long even
in the winter without communal living or physidontical heterothermy. (Merrit 1986)
Diet:
Short-tailed shrews are voracious eaters with a high metabolic rate that requires them to
consume over half their body weight in food. (Boonstra 2002, Whitaker 1996) They have
a diverse diet including small amounts of seed and fungi but are mostly carnivorous
preying on earthworms, millipedes, spiders, slugs, snakes and small vertebrates.
(Benedict 1999) With the aid of venom produced by the sub maxillary glands they can
even prey on smaller shrews, voles, mice, salamanders and snakes. (Kurta 1995) The
venom functions as an immobilizing agent that puts its prey into a catatonic state. This
allows the short-tailed shrew to store its prey so it is fresh for a period of time after
captured. Thus insures predictable quick energy sources that will be readily available as
a buffer against prey scarcity. (Merrit 1986) Because their eyes are rudimentary and can
only sense light vs. dark, short-tails relay on their fine-tuned sense of touch and ability to
echolocate to locate their food. (Kurta 1995)
Remarks:
Short-tail shrews have been playing an important role in the ecosystem for many years,
first appearing in the late Pliocene about 3 million years ago. (Benedict 1999) Because of
their abundant population they provide food for many different carnivores such as the
coyote, pine martin, badger, fisher, long-tailed weasel, mink and bobcat. (Kurta 1995)
They also are responsible for keeping population checks on larch sawflies and other
destructive insects. (Jackson 1961)
Work Cited
Benedict, R.A. 1999 Morphological and mitochondrial DNA variation in a hybrid zone
between short-tailed (Blarnia) in Nebraska. Journal of Mammology 80:112-34
Boonstra, R. 2002. Demography of short-tailed shrew populations living on PCB
contaminated sites. University of Toronto. Ontario, Canada.
Brant, S.V. 2003. Phylogeography of the northern short-tailed shrew, Blarina brevicauda
(Insectivore: Soricidae): past fragmentation and postglacial recolonization.
Molecular Ecology. 12:1435-49
Jackson, H.H.T. 1961. Mammals of Wisconsin. The University of Wisconsin Press,
Madison, Wisconsin. pp. 42-55.
Kurta, A. 1995. Shrews. Pages 46-49. Mammals of The Great Lakes Region.University
of Michigan Press, U.S.A.
Merritt, J.F. 1986. Winter survival adaptations of the short-tailed shrew (Blarnia b.) in
Appalachian Montane forest. Journal of Mammology.67: 450-64
Whitaker, J.O. 1996. Shrews. Pages 2998-299. National Audubon Society, Field Guide
to Mammals. Chanticlerr Press, Inc.
Reference written by Sheri Robb, Biol 378: Edited by Chris Yahnke. Page last updated