Description and Range
The canyon bat (formerly known as the western pipistrelle) is one of the smallest bats in Washington and North America. The face, ears, and flight membranes are blackish and contrast with the paler fur, which varies from pale yellowish or orange-yellow to gray-brown. The short (usually half the length of the ear) blunt, club-shaped tragus distinguishes this species from California myotis and western small footed myotis. The hind foot is less than half the length of the tibia and the calcar is keeled
Food Habits and Foraging
The diet includes small swarming insects such as moths, leafhoppers, flying ants, mosquitoes, and fruit flies. In eastern Oregon, the most common prey were flies, moths, hymenopterans, beetles, true bugs, and leafhoppers. Canyon bats are slow and weak fliers. Foraging often begins before sunset and may continue until well after dawn. Early evening activity usually decreases 1-2 hours after sunset. Foraging occurs in a variety of habitats, including canyons, along cliffs, in riparian zones, and over lava beds.
Mating likely happens in the fall, with ovulation and fertilization occurring in spring. Females are pregnant for about 40 days. Births take place from late May through early July, with two young born per litter.
Canyon bats are mainly distributed from the southwestern U.S. to central Mexico, but a narrow finger of the species’ range extends into eastern Oregon and eastern Washington, which is the northern extent of the species’ range. The species has been reported from 10 eastern Washington counties, with most records coming from along the Columbia and Snake rivers and large coulees.
Canyon bats occur most commonly in lowland arid habitats, including desert, dry grasslands, shrub-steppe, and associated riparian zones. Canyon environments with cliffs are especially preferred. Elevations from sea level to 2,825 m are inhabited. In Washington, the species has been detected most often in deep river canyons and coulees with shrub-steppe, especially at rocky locations. At Hanford, it has also been recorded infrequently at sites with buildings, bunchgrass, dunes, ponds, rivers, and trees. In Moses Coulee, it occurs in shrub-steppe, riparian zones, and near cliffs, including some sites distant from water sources.
Little is known about the summer and winter roosting ecology of canyon bats in the Pacific Northwest. Canyon bats prefer day roosting in small crevices of cliffs, rock outcrops, caves, mines, and buildings, but rodent burrows and sites beneath rocks are possibly occupied as well. Females with young roost solitarily or form small maternity colonies of less than 20 individuals. Maternity roosts occur separately from the day roosts of males and non-reproductive females. Little information exists on night roosts, but use of mines has been reported. There is suggestion that canyon bats perch on sagebrush at night.
During hibernation, individuals may regularly arouse to forage on warm winter days, with males appearing to be more active in winter than females. Canyon bats are considered non-migratory.
- Based on the little available information from other states, cliffs, rock outcrops, and mines may be important roost sites for canyon bats and should be surveyed for seasonal presence of this species.
- Where roosting habitat occurs, it should be identified and not disturbed.
- Steps should be taken to reduce the conversion of shrub-steppe and grassland near cliff faces to preserve accessible foraging habitat.
For some people bats don't present a problem. For others, bats can be a worry, especially when they become unwanted guests in an attic, inside a wall of a home, or inside the home itself.
Unlike rodents, bats only have small teeth for eating insects, so they do not gnaw holes in walls, shred material for nests, chew electrical wiring, or cause structural damage to buildings. Damage caused by bats is usually minimal, but they can be noisy and alarming, and the smell of bats and their droppings can be offensive. It is possible to learn to coexist with bats, and to benefit from their presence. Learn more on our Living with Wildlife: Bats webpage.