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.
These animals are found in the following types of habitat:
temperate 
; terrestrial .
Terrestrial Biomes:
savanna or grassland ; forest ; mountains .
Wetlands: bog .
Physical Description
(0.21 to 0.39 oz)
(4.33 to 4.96 in)
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.
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry .
Reproduction
1-3 litters per year
Mating starts in late March, and may continue into late September
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)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous .
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).
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.
Key behaviors:
diurnal ; nocturnal ; crepuscular ; motile ; sedentary .
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.
Primary Diet:
carnivore (insectivore ).
Animal Foods:
insects; terrestrial non-insect arthropods; mollusks; terrestrial worms.
Other Foods:
fungus.
Foraging Behaviors:
stores or caches food .
Conservation Status
IUCN Red List: [link]:
Lower Risk - Least Concern.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
State of Michigan List: [link]:
Special Concern.
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.
For More Information
Find Sorex fumeus information at
Contributors
Nancy Shefferly (editor), Animal Diversity Web Staff.
Bret Weinstein (author), University of Michigan.
