More Information

Additional Information

Sorex fumeussmoky shrew

By Bret Weinstein

Geographic Range

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)

Habitat

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.

Physical Description

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

Reproduction

Reproductive season extends from March to October. Smoky shrews never reproduce in their first year, but rather overwinter as subadults. Their gestation period is less than three weeks and birth is followed by immediate postpartum estrus. Litter size can range from 2 to 8, average is 6. (Kurta, 1995)

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)

  • Breeding interval
    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
    5
    AnAge
  • Average gestation period
    20 days
  • Average gestation period
    21 days
    AnAge
  • 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
    AnAge
  • Average age at sexual or reproductive maturity (male)
    6 months
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    304 days
    AnAge

Male smoky shrews provide no parental investment. Females make nests in leaf litter. Pups are altricial, blind and furless at birth. Exact duration of the period of nursing and parental protection is unknown, but ends before the next litter is born. (Kurta, 1995)

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

Lifespan / Longevity

Behavior

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.

Communication and Perception

Food Habits

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

Conservation Status

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.

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

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

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

References

Mammalian Species #215

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

Search

Navigation Links

Information
Pictures
Specimens
Classification

Classification