Why that’s as big as a full grown wolf!—Thorne Sherman in The Killer Shrews (1959)
As implied by its name, the shrew mole has features of both. It is in the family Talpadae with the moles but differs in a variety of ways. Its teeth are white, which is typical of moles and in contrast to the reddish pigment (from iron) in the teeth of shrews, it has guard hairs and underfur similar to shrews, and its feet are turned forward like shrews, which can put their front feet flat on the ground. In contrast, mole feet are turned sideways for more efficient digging. But shrew moles have a skeletal adaptation – a squarish humerus (upper arm bone) that allows for large muscle attachment and an odd connection between its clavicle and humerus that provides better digging power. Moles also have hairless snouts – the shrew mole has a hair, flexible snout like a shrew. Moles have 44 teeth and shrew moles have 36. Got it? Overall though – they look more like a shrew than a mole and have been plopped in a special sub-family within the larger mole family. Their closet relative is a somewhat similar Japanese species.
This North American species is found in damp forested or brushy areas with pliable soils. It is found along the west coast from Monterey County, California. Most of the time it is found below 800 ft. elevation but has been recorded as high as 8,000 ft.
Unlike moles, shrew moles spend a good deal of time above ground foraging but they will forage in the tunnels they did. They also will make use of tunnels dug by others. They also are known to be agile enough to climb bushes while foraging and can swim pretty well. They sometimes form small groups (pods, tribes, herds?) and appear to move together as a group (up to 11 have been observed) for a few days and then disperse. More typically they achieve a density of 5-6 per acre.
Shew moles will develop two types of tunnels – a shallow one just beneath the leaf litter and a second, less common one no deeper than a foot below the surface. They will widen parts of the shallow tunnels to create a sleeping chamber and they typically construct a small vent hole as well. Earthworms make up a large proportion of their diet but they also eat insect larvae, snails, slugs, centipedes, sow bugs, fungus, and seeds. In turn they are preyed upon by owls, hawks, coyotes, garter snakes, raccoons, and weasels.
As with all shrews they have a very high metabolism and can eat 1.4 times their weight in 12 hours and can die of starvation quickly. They are active all year and typically sleep no more than 8 minutes at a time – but then again are active for 20 minutes and then take a nap. Their nose is sensitive and is used in probing for food – a good thing since they are blind and they have no external ears. They weigh only 0.35 ounces and are about 5 inches long, including their tail. When alarmed they will make a quick dash for cover and remain motionless.
You can scan through this video to see how hyperactive they are: Foraging
Shew moles breed once a year, anytime between February and August, and typically have three young. The gestation period is about 4 weeks and is born in below or above ground nests.
Neurotrichus – Latin nervus (sinew or tendon) and trichos (hair) –likely a reference to the shrew mole’s tail. The specific name – gibbsii is after George Gibbs who captured the first specimen at White River Pass, north of Mt. Rainier on July 15, 1854. Gibbs, a naturalist and ethnologist, was part of the Pacific Railroad Survey that laid out the route between Puget Sound and the Spokane River.
I’ve only seen these animals while conducting small mammal live trap studies in the Puget Sound area. And like other shrews, these things have a pretty pungent odor from scent glands. Unfortunately, like shrews, their metabolism is so high they often do not survive the evening in a trap even with bedding and some food. I have caught several live ones, however. Once, on a cool morning, I caught one and he was rather lethargic. So I put him in my pants pocket making the rounds to the other traps. After about a half hour he started stirring around so a dropped him off where I found him and he scurried off.