Remarks.—Shrew-moles inhabit moist habitats from sea level to 8,000 feet. They are burrowing mammals and prefer to live in soft earth, free of sod. In the lowlands of western Washington, shrew-moles are most abundant in damp, shady ravines where the vegetation includes deciduous trees and dense underbrush with but little grass. In the mountains, shrew-moles are usually found near streams or rock slides, where the larger annuals grow densely on soil that is deep, soft, and free of turf. Vertically they range from the Humid Transition Life-zone through the Canadian, and well into the Hudsonian Life-zone.
Fig. 22. Distribution of the [Gibbs] shrew-mole in Washington. A. Neurotrichus gibbsii gibbsii. B. Neurotrichus gibbsii minor.
Shrew-moles are both diurnal and nocturnal. They rest or sleep periodically, the length of their rest or sleep being longer when much food is eaten, and the intervals between their periods of rest or sleep is longer when less food is eaten. Owls and snakes appear to be their principal enemies. Predatory mammals eat some shrew-moles, and probably kill many that they do not eat. Shrew-moles are completely blind, and their long, prehensile nose guides all their activity. Their ordinary movements on the surface of the ground are slow and cautious. When frightened they break into a scuttling rush which ends beneath a leaf or bit of bark where the animal becomes motionless. Shrew-moles, on the surface of the ground, make considerable noise. They construct molelike burrows, but these are not as extensive or complicated as those of moles. The shrew-mole hunts for food in shallow trenches that it makes just under the layer of dead leaves and vegetable debris that covers the ground in their habitat. The food of the shrew-moles includes earthworms, isopods, insect larvae, soft-bodied insects, and other animal matter. Some vegetable matter is eaten.
Breeding takes place at all seasons of the year, save perhaps in December and January. Embryos vary from one to four. The nest of a shrew-mole at Seattle, King County, consisted of a handful of damp leaves in a cavity of a rotten, punky, alder stump. The nest contained four half-grown young.
Neurotrichus gibbsii gibbsii ([Baird])
Urotrichus gibbsii [Baird], Mamm. N. Amer., p. 76, 1857.
Neurotrichus [sic] gibbsii Günther, Proc. Zool. Soc. London, pl. 42, 1880.
Neurotrichus Gibbsii True, Proc. U. S. Nat. Mus., 7 (1884):607, 1885.