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Neurotrichus gibbsii
American shrew mole


By Emily Gochis

Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Soricomorpha
Family: Talpidae
Genus: Neurotrichus
Species: Neurotrichus gibbsii

Geographic Range

Neurotrichus gibbsii is found in western North America, from mid-California to lower British Columbia. It ranges from the Pacific Ocean to the Cascade and Sierra Nevada mountains. Shrew-moles are also found on Destruction Island, Washington (Campbell, 2001).

Biogeographic Regions
nearctic (Native )

Habitat

Range elevation
sea level to 2500 m
( to 8202.10 ft)

N. gibbsii prefer soils that are easy to dig, and where there is plenty of organic matter. They are mostly found in the temperate rainforests of northwest North America, where soils are soft and deep. Shrew-moles can also be found in areas that are moist and weedy or brushy (Campbell, 2001).

Habitat Regions
temperate

Terrestrial Biomes
rainforest

Physical Description

Range mass
8 to 14.5 g
(0.28 to 0.51 oz)

Average mass
10 g
(0.35 oz)

Range length
100 to 130 mm
(3.94 to 5.12 in)

Average length
120 mm
(4.72 in)

N. gibbsii is the smallest species of New World Talpidae (Wilson and Ruff, 1999). Its hair is black or blue-black and not as plush as other moles (Dalquest, 1942). Shrew-moles' forefeet are slightly broadened, not webbed and modified for digging only (Wilson and Ruff, 1999). The external ears are absent. Eyes are greatly reduced, and these animals have a flat, elongated nose (Carraway, 1991). The tail is about half as long as the body and reasonably wide (Reed, 1951). N. gibbsii show no sexual diamorphism and its dental formula is 3/3, 1/1, 2/2, 3/3= 36 (Carraway, 1991).

Other Physical Features
endothermic ; bilateral symmetry

Reproduction

Mating System
polygynandrous (promiscuous)

Breeding season
usually lasts from late February to August

Range number of offspring
1 to 4

Average number of offspring
3

Average gestation period
unknown minutes

Shrew-mole has a relatively long breeding season. Reproduction happens once a year and lasts from late February to August. The length of the gestation period is unknown, but is assumed to be at least four weeks long (Yates, 1982). The nests are built above ground, although one nest was observed in a stump about a meter off the ground (Dalquest, 1942). The babies are born blind and weigh less than a gram (Wilson and Ruff, 1999).

Parental Investment
altricial ; female parental care

Behavior

Shrew-moles are active both day and night, and they only sleep for one to eight minutes at a time. They stay awake for periods ranging from two to eighteen minutes long. They do not hibernate (Carraway, 1991).

Unlike other moles, N. gibbsii spend a lot of time above ground and move around easily (Wilson,1999). They are also known to be deliberate climbers, and can easily climb up low bushes in search of food or a nesting place (Dalquest, 1942).

Shrew-moles are also very good swimmers and use all of their limbs and tail to move through the water (Callaway, 1991).

Shrew-moles are gregarious and may even travel in groups that have over 11 individuals. These groups seem to move together to an area, stay there up to several days, and then move on together to another area (Dalquest, 1942).

Like other moles, N. gibbsii are fossorial and use their tunnels for both movement and hunting (Campbell, 2001). They create two different types of tunnels. The first is shallow and dug directly beneath leaf litter. The second is less common and deeper, but never below 30 cm (Yates, 1982). Shrew-moles also widen parts of their shallow tunnels to create a sleeping chamber. These chambers can be found above ground because they have a vent hole that allows the animal to breath while sleeping (Racey, 1929). These tunnels are different than those of other moles because they have open entrances, no "mole hills" and are less complex (Callaway, 1991).

Food Habits

N. gibbsii need a lots of food, compared to thier body size, because of their high metabolism. Dalquest (1942) observed that shrew-moles are capable of eating up to 1.4 times their own body weight in twelve hours and can die of starvation very quickly. He also observed that they use their nose to locate prey. He describes the process of a Shrew-mole walking up to the prey and "rapping" its nose on the ground right in front of the prey, then turning its head to the right and rapping on the ground again. It will repeate this motion, but turning its head to the left. These motions are repeated very quickly until the shrew-mole's nose touches the prey. Shrew-moles also use their long noses to push over insect pupae and isopods (Dalquest, 1942). N. gibbsii capture earthworms and other prey when they fall into the tunnels they dig. Earthworms are their prefered food (Yates,1982).

Foods eaten include: earthworms, insect larvae, snails, slugs, centipedes, sow bugs, fungus and seeds.

Animal Foods
insects; terrestrial non-insect arthropods; mollusks; terrestrial worms

Plant Foods
seeds, grains, and nuts

Predation

Known Predators


Dalquest (1942) observed that if a Shrew-mole is scared into hiding, it will reemerge in search of food in less than a minute. This makes them an easy target for predators, though they are not the major diet of any species (Racey,1929). Owls seem to be their biggest predator (Carraway, 1991).

Economic Importance for Humans: Positive

N. gibbsii do have an effect on controlling bark beetles and other harmful insects in their own habitats. But this is of minimal economic benefit, because most areas where the shrew-mole is found are bad sites for logging or farming (Dalquest, 1942).

Positive Impacts
controls pest population

Conservation Status

IUCN Red List [Link]
Lower Risk - Least Concern

US Federal List [Link]
No special status

CITES [Link]
No special status

American Shrew-moles are described to be "common" throughout their range (Wilson and Ruff, 1999).

For More Information

Find Neurotrichus gibbsii information at

Contributors

Emily Gochis (author), University of Michigan, Ondrej Podlaha (editor), University of Michigan.

References

Campbell, K. "American shrew-mole" (On-line). Accessed 10/09/01 at http://home.cc.umanitoba.ca/~rmacarth/shrewmole.html.

Carraway, L., B. Verts. 1991. Neurotrichus gibbsii. Mammalian Species, 387: 1-7.

Dalquest, W., D. Orcutt. 1942. The biology of the least shrew-mole, Neurotrichus gibbsii minor. The American Midland Naturalist, 27: 387-401.

Racey, K. 1929. Observations on the Neurotrichus gibbsii. The Murrelet, 10: 61-62.

Wilson, D., S. Ruff. 1999. The Smithsonian Book of North American Mammals. Washinton: Smithsonian Institution Press.

Yates, T., R. Pedersen. 1982. Moles: Talpidae. Pp. 37-51 in J Chapman, G Feldhamer, eds. Wild Animals of North America. Baltimore: John Hopkins University Press.

To cite this page: Gochis, E. 2002. "Neurotrichus gibbsii" (On-line), Animal Diversity Web. Accessed February 12, 2012 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Neurotrichus_gibbsii.html

Disclaimer: The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

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