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smoky shrew

Sorex fumeus

What do they look like?

Smoky shrews get their name from the gray or black color of their body fur in winter, in summer it is dull brown. The fur on their belly is usually the same color as the back, or a little lighter. One distinctive trait is it's bicolored tail: dark on top, but tan underneath. Total length is 110 to 126 mm, tail length 42-52 mm. Adults weigh 6-11 g. Like all shrews they have a long, cone-shaped snout, many sharp teeth, small (but functional) eyes, and fur that is short but soft and dense.

  • Range mass
    6 to 11 g
    0.21 to 0.39 oz
  • Range length
    110 to 126 mm
    4.33 to 4.96 in

Where do they live?

Smoky shrews are found in the eastern United States and Canada. In Canada they range from the eastern shore of Lake Superior east to the Atlantic Ocean and south to the U.S. border. In the U.S. they are found in New England, south along the Appalachian Mountains to the western tip of South Carolina, and west of the mountains into Kentucky and central Ohio. The species has only been found in one location in Michigan, on Sugar Island in the St. Mary's River, between the Upper Peninsula and Ontario. (Kurta, 1995)

What kind of habitat do they need?

Smoky shrews generally live in the leaf litter on the floor of deciduous and coniferous forests. They are often found near rotting logs or moss-covered rocks. They have also been observed in bogs, swamps and grasslands.

How do they reproduce?

Smoky shrews start mating in late March, and females give birth to their first litters in April or May, about 20 days after mating. They mate again a soon as the first litter is born, and they may have 2 more litters, each about a month apart, if the female lives long enough. Each litter has 2 to 8 pups, usually 6. (Kurta, 1995)

  • How often does reproduction occur?
    1-3 litters per year
  • Breeding season
    Mating starts in late March, and may continue into late September
  • Range number of offspring
    2 to 8
  • Average number of offspring
  • Average gestation period
    20 days
  • Average gestation period
    21 days
  • Range weaning age
    20 (high) days
  • Average age at sexual or reproductive maturity (female)
    6 months
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    304 days
  • Average age at sexual or reproductive maturity (male)
    6 months
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    304 days

Male smoky shrews don't take care of their offspring, only the female does. Females make nests in leaf litter where they give birth. The offspring are blind, helpless, and have no fur. Females nurse and protect their offspring for a short time (less than 20 days). (Kurta, 1995)

  • Parental Investment
  • altricial
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

How long do they live?

How do they behave?

Smoky shrews are active all year round. They move about and hunt in tunnel systems created by other small mammals (including other shrews). The nest of a smoky shrew is about 23 cm in diameter and may be located in a rotting log or under the leaf litter.

Individuals in populations tend to be clumped. The known predators of smoky shrews include owls, foxes, bobcats, hawks, weasels and short-tailed shrews (Blarina brevicauda). Almost all smoky shrews that survive their first winter die in the winter following their first reproductive season.

How do they communicate with each other?

What do they eat?

Smoky shrews eat a wide variety of insects. They also eat earthworms, spiders and some fungi. In captivity they will also eat plethodontid salamanders, but it is not known if they seek them in the wild.

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms
  • Other Foods
  • fungus

Are they endangered?

This species is fairly common, and not considered in need of special conservation efforts. Because it is so rare in the spate, it is considered a Species of Special Concern in Michigan.


Nancy Shefferly (editor), Animal Diversity Web.

Bret Weinstein (author), University of Michigan-Ann Arbor.


Mammalian Species #215

Kurta, A. 1995. Mammals of the Great Lakes Region. Ann Arbor, Michigan, USA: The University of Michigan Press.

University of Michigan Museum of ZoologyNational Science Foundation

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Weinstein, B. 1999. "Sorex fumeus" (On-line), Animal Diversity Web. Accessed March 29, 2017 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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