Least Shrew

LEAST SHREW

Photo Credit: F. A. Cervantes Reza and the
Mammal Images Library of the American Society of Mammalogists

SCIENTIFIC NAME: Cryptotis parva

DESCRIPTION: The least shrew (cryptotis parva) is a tiny mammal.  In fact, the shrew family Soricidae includes some of the smallest members of the animal kingdom.  It weighs 1/7 to 1/4 ounce  and is 2-1/5 to 2-1/2 inches in length.  This shrew has a short tail measuring 1/2 to 3/4 inches.  Body color ranges from a dark grayish to reddish brown on its upper parts with a contrasting lighter grayish colored belly.  Shrews have long tapering snouts, tiny eyes and small ears concealed in short fine fur.

DISTRIBUTION: The least shrew is found throughout the eastern United States south of a line from central New York to central South Dakota, through western Nebraska, eastern Colorado, and western Kansas, and through Oklahoma and Texas to New Mexico.  It is found statewide in Alabama.

HABITAT: The least shrew prefers grassy open lands, along edges of openings, and may be also found in open forests and marsh habitats.

FEEDING HABITS:  Shrews are insectivores, meaning they feed on insects and lots of them.  For their size, shrews are some of the most voracious and ferocious predators of the animal kingdom, eating their body weight or greater in food daily.  The least shrew’s physique is especially designed for hunting and capturing insects.  Its body is streamlined with a unique pointed snout equipped with a highly movable and functional nose and very sharp teeth for killing and tearing its prey.  The shrew has poor hearing and eyesight, but has movable vibrissae (whiskers) around the nose and mouth which provide a very keen vibratory sense to detect movement, aiding the shrew greatly in locating insects.  The least shrew hunts by the senses of touch and smell at the ground surface or just underneath loose soil and leaf litter for unsuspecting prey.  It is active at all hours of the day with peak activity at night (nocturnal).  Preferred food items are grasshoppers, beetles and crickets; hence, its niche to inhabit grassland habitat types where these insects can be found in abundance.

LIFE HISTORY AND ECOLOGY: The least shrew is more sociable than other members of the shrew family.  As many as 31 individuals were found in one nest during the winter.  The least shrew breeds year-round and normally produces several litters per year.  Nests are made of dried grasses and leaves located under debris or beneath the surface of the ground.  After a gestation period of about 21 days, two to six tiny young are born naked with their eyes and ears closed.  Both parents care for young which within a month are fully weaned and resembling adults. These young shrews are capable of breeding shortly afterwards.  The least shrew is one of the most adaptable and wide ranging of all North American shrews.  It has a very high metabolic rate and burns up tremendous amounts of energy in a short duration of time.  When not at rest it is almost in constant motion.  With such a fast-paced lifestyle, the shrew literally burns itself out, having an average life span of less than one year.  Chief predators are hawks, owls and snakes.  Shrews, through their outrageous appetite for insects, help control destructive pests in grassland and forested habitats.  The least shrew though small and secretive, has a special place within the realm of natural things, making an important contribution to the cycle of life.

REFERENCES: 

Burt, William H., and Richard P. Grossenheiden. 1976.  A Field Guide to the Mammals.  Houghton Mifflin Company, Boston. Pp. 2-16.

www.discoverlife.org 
Cryptotis parva, Last Modified:  8 April, 2002.

Author: Rick Claybrook, Supervising Wildlife Biologist, Division of Wildlife and Freshwater Fisheries.