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By Emily Gochis
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).
Habitat
( to 8200 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).
These animals are found in the following types of habitat:
temperate
.
Terrestrial Biomes:
rainforest
.
Physical Description
(0.28 to 0.51 oz; avg. 0.35 oz)
(3.94 to 5.12 in; avg. 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).
Some key physical features:
endothermic
; bilateral symmetry
.
Reproduction
usually lasts from late February to August
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).
Key reproductive features:
gonochoric/gonochoristic/dioecious (sexes separate); sexual
.
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).
Key behaviors:
motile
.
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.
Primary Diet:
carnivore
(vermivore).
Animal Foods:
insects; terrestrial non-insect arthropods; mollusks; terrestrial worms.
Plant Foods:
seeds, grains, and nuts.
Predation
- owls (Strigiformes)
- snakes (Serpentes)
- red-tailed hawks (Buteo jamaicensis)
- raccoons (Procyon lotor)
- swift foxes (Vulpes velox)
- coyotes (Canis latrans)
- domestic dogs (Canis lupus familiaris)
- domestic cats (Felis silvestris)
- gray foxes (Urocyon cinereoargenteus)
- red foxes (Vulpes vulpes)
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).
Ways that people benefit from these animals:
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).
Contributors
Emily Gochis (author), University of Michigan.
Ondrej Podlaha (editor), University of Michigan.


