Meet Washington's Bats

Washington state is home to 14 species of bats. Ten species live across the state, and four species are found only in eastern Washington. Our bats live in many different habitats and can be found living and foraging even in suburban and urban areas. Seven of our species have been recorded right in Seattle! Explore each of our local species below.

Big Brown Bat (Eptesicus fuscus)

Big brown bats are a larger species of microbats, weighing 15-26 g. Their wingspan is 32.6-35 cm with black wing membranes. They have a heavy body, a large head with a broad nose, short round ears and a black face mask. The dorsal fur of the big brown bat is reddish brown and glossy in appearance, while their ventral fur is lighter brown.
Big brown bats have powerful jaw muscles and heavy teeth. This species will forage in large circles high above ground but descend to feed within 15 m of the ground. They prefer to forage above canopies, forest edges, along roads, and in open areas such as clearings and waterways.
Big brown bats are closely associated with human structures and can be found roosting in attics, barns, bridges during the summer seasons. They will also roost in trees, snags and caves. During the winter big brown bats travel less than 90 km to hibernate in subterranean roosts like caves, mines or deep rock crevices. Maternity roosts have been recorded to contain several hundred individuals. Births of pups occur from June to July, with flying young appearing in August.
Big brown bats range from southern and central Canada to northern South America and the Caribbean. Big brown bats are habitat generalists and live in a variety of forests, shrub-steppes, alpine and urban areas.
Many forest-dwelling populations of big brown bats rely on standing snags (dead or dying trees) for roosts. Identifying and maintaining standing large snags allows big brown bats and other animals to find shelter.

California Myotis (Myotis californicus)

California myotis is one of the smallest bat species in Washington, weighing about 3-5 g. Their forearms reach 2.6-4.0 cm in length, while their wingspan is around 22-23 cm with black flight membranes. Their fur is dull and ranges in color from rusty to blackish brown. They have relatively short black ears with a long tragus. California myotis’ appearance is similar to the western small-footed myotis, but the California myotis often has darker fur with less contrast against their darker skin.
California myotis begin foraging before dark and seek out large concentrations of insects over water, within canopies, and along forest margins. Slow maneuverable flight and high-frequency echolocation calls allow them to detect and catch prey at close ranges.
Roosting occurs in loose tree bark, rock crevices, tree cavities, mines, caves, buildings, and bridges. California myotis often switch roosts during the summer. During winter the California myotis hibernate alone or in small groups within buildings, caves, and mines. In the Puget Sound region, California myotis may not fully hibernate as they are able to be active on relatively warm winter nights. Maternity colonies are small and consist of around 20 individuals or fewer. Single pup births occur from May to early July, and pups can fly at about one month of age.
California myotis range from Alaska, throughout the western U.S., and south to Guatemala. California myotis can be found in habitats containing water sources, including deserts, canyons, shrub-steppe, and dry and humid forests.
Placing shelters such as bat houses will provide potential homes to resident bats. Visit batsnorthwest.org to learn to make your own bat boxes and some best practices for placing it in your yard.

A western pipistrelle bat (Pipistrellus hesperus) flying over desert scrub near Pine Creek in the John Day Fossil Beds National Monument, Clarno Unit, Oregon. This is the smallest bat found north of Mexico.

Canyon Bat (Parastrellus hesperus)

Formerly known as the western pipistrelle, the canyon bat is the smallest species in the U.S., weighing 3-6 g. With a short wingspan of 19-22 cm and forearms that are 2.6-3.3 cm in length, they are sometimes mistaken for moths. The face, ears, and flight membrane of the canyon bat are black, while their fur ranges from pale yellow to dark grayish-brown.
Among the most diurnal of bats, canyon bats may begin foraging before sunset and continue intermittently until well after dawn. Canyon bats’ short broad wings allow them to fly at speeds as low as S mph with high maneuverability. Their erratic, fluttery flight aids them in catching swarming insects.
During the summer months canyon bats roost in small crevices of cliffs, rock outcrops, caves, mines and possibly rodent burrows. During winter canyon bats are thought to be non-migratory, and usually hibernate solitarily. Females with young often roost solitarily but may form maternity colonies of up to 12 individuals. Females give birth to twin pups in June or July. Juveniles will begin flying by one month of age.
Canyon bats range throughout the southwestern U.S. to central Mexico. A narrow range extends through eastern Oregon and into 10 eastern Washington counties. Canyon bats prefer arid habitats such as deserts, canyon environments, dry grasslands,
shrub-steppe, and similar riparian zones.
Bats roosting in cliff crevices can be disturbed during human recreational activities such as rock climbing. Learning to identify potential roosting habitats can mitigate disturbances.

A fringed bat (Myotis Thysanodes) flying above a pond in the high-desert of Central Oregon. This bat is very similar to Mytois evotis and is distinguished by the fringe on its tail membrane. Near Fort Rock State Monument, Dechutes National Forest, Oregon.

Fringed Myotis (Myotis thysanodes)

Fringed myotis are small bats but are one of the largest “myotis” species in Washington, weighing 5-7 g with a wingspan of
27-30 cm and a forearm length of 3.2-4.6 cm. Their fur color ranges from yellowish brown to dark olive, with little contrast between their back and underside. Their flight membrane and long ears are black in color. They look like the other long-eared myotis species but can be identified by a fringe of short wire-like hairs along the trailing edge of the tail membrane.
Fringed myotis have short, broad wings allowing them to fly at low speeds with high maneuverability for aerial capture and gleaning prey from foliage. Foraging takes place over water, in forests and along forest edges. They emerge from their roosts within 1-2 hours after sunset. Rocky outcrops, snags, and rock crevices make suitable day roosts for fringed myotis in eastern Washington. During winter fringed myotis appear to migrate but little is known about their movements or hibernation sites.
Maternity colonies found in caves rarely exceed 1,000 individuals. Mothers will give birth to a single pup in late June to early July. The young are raised in clusters separate from adults and are capable of full flight after 21 days.
Fringed myotis are found in much of western North America, from south-central B.C. to southern Mexico. In Washington, they are primarily seen east of the Cascades. Habitats such as
shrub-steppe, coniferous forests, and grasslands are suitable when water sources are available.
Maintaining diverse roosting structures in suitable habitats is vital to bat populations. Protecting potential day roost sites in large-diameter snags and maintaining the integrity of basalt rock outcrops and talus slopes in proximity to foraging and drinking sites is important for bat conservation.

Little Brown Myotis (Myotis lucifugus)

A little brown bat (Myotis lucifugus) flies at night at The Nature Conservancy’s Dutch Henry Falls preserve in central Washington.

Little brown myotis is widely distributed and commonly seen by people. Little brown myotis is a medium-sized myotis species, weighing around 7-14 g with a wingspan of 22-27 cm, and a forearm length of 3.1-4.1 cm. Their glossy-sheened fur comes in a variety of colors from pale tan to olive with a paler ventral section. Their ears and flight membranes are dark brown. Physically, little brown and yuma myotis appear very similar. The most reliable physical discriminators are forearm length and the characteristic frequency of the echolocation pulse emitted by the bats.
Little brown myotis forage along forest edges and near or over water, often hunting within 5 m off the ground in circular and zigzagging patterns. They specialize in hunting small insects, using high-frequency echolocation and their rounded wing tips for aid in maneuvering. Summer roosts include buildings, tree cavities, and beneath bark, caves, and mines. During the winter little brown myotis hibernate in caves, mines, and lava tubes. Maternity colonies can form groups of over 1,000 individuals. Single pup births occur in June, but may be delayed due to cooler weather.
Little brown myotis range throughout most of North America, from northern Canada and Alaska to California and the southeastern U.S. They are habitat generalists and occur throughout a broad range of habitats, including forests, urban buildings and bridges.
White Nose Syndrome (WNS) is a fungal disease that has wiped out millions of bats. The little brown myotis has gone from being one of the most common bats in the U.S. to being endangered. Supporting organizations such as Bats Northwest helps us understand the spread of this disease and work to conserve local species.

Long-legged Myotis (Myotis volans)

A western long-legged myotis (Myotis volans) at a watering hole in the high-desert of Oregon.

Long-legged myotis, while still considered a small bat, is one of the larger species of myotis, weighing 6-9 g, with a wingspan of 25-27 cm, and a forearm length of 3.2-4.9 cm. Their dorsal fur color ranges from reddish brown to black.
The fur on the ventral area is relatively darker than above and extends to the undersides of the wing. Their short ears are rounded at the tips and are blackish brown in color. Their name refers to the longer tibia length compared to other myotis species.
Long-legged myotis capture prey in midair along forest edges, and over canopies and cliff sides. Their flight patterns are rapid and direct. Emergence from day roosts occurs in the early evening, where they forage throughout the first 3-4 hours of the night.
Roosting during the summer months takes place in snags, trees, crevices in rocks, buildings, bridges, caves, and mines. They will switch roosts about once every 2-3 days. During the winter months, from November to March, long-legged myotis hibernate in caves and mines. Maternity colonies consist of fewer than SO bats. Mothers give birth to one pup per year in late June to mid-August.
Long-legged myotis are found from southeastern Alaska, east to North Dakota, and south to Mexico. They inhabit both moist and dry coniferous forests and can also be found in riparian forests and dry rangeland. They have a strong preference for old-growth forests, up to 3,500 m in elevation.
Pesticides used to control insects can become concentrated in predators that feed on the insects by the process of trophic concentration. Using non-chemical control methods for managing pests can prevent harmful pesticides from harming bats.

Hoary Bat (Lasiurus cinereus)

Male hoary bat (Lasiurus cinereus), Photographed near the Conasauga River in the Chattahoochee National Forest, Georgia.

The hoary bat is the largest bat in Washington, weighing 25-30 g. Their forearms range from 4.1-5.8 cm adding to their impressive 34-41 cm wingspan. The name “hoary”, meaning “frosty in appearance”, comes from the white tips on their black to yellow-brown fur. The surface of the tail is furred, unlike all other bat species found in Washington except the silver-haired bat. Their wings, which are not furred on either side, are long and narrow with blackish brown membranes and brown stripes along the forearm. Their ears are short and round with dark margins. Female hoary bats are up to 40% larger than males.
Hoary bats are fast, straight fliers with less maneuverability than most bats. With a low frequency echolocation, long range detection of prey is most successful in open areas above canopies and over clearings. Feeding territories are established and defended by individuals. If another bat enters the territory it will be chased out. Hoary bats mainly roost in large trees; they roost alone unless they are raising young. Pups can be carried in flight until they are about 6-7 days old. Births of one to four pups are possible in a single litter with an average of two pups per litter. Hoary bats are long distance migrators and a significant portion of the population spends the winter season in California and Mexico.
Hoary bats are the most widespread bat in North America, and are the only bat occurring in Hawaii. They have been found in most Washington counties. Hoary bats prefer a variety of forest types with a strong preference for late successional forests.
Over 40% of all bats killed by wind turbines have been hoary bats. Innovative ideas and creative thinking will allow for advancements in protection in the field of sustainable energy. Mitigation efforts such as siting wind turbines away from migratory pathways and curtailing turbine use when wind speed is low could help reduce bat mortality at wind energy facilities.

Pallid Bat (Antrozous pallidus)

A pallid bat (Antrozous pallidus) flying at night near Sulphur Springs, high-desert habitat, Washington.

Pallid bats are the second largest bat in Washington state, weighing about 20-35 g, with a wingspan of 37-39 cm, and a forearm length of 4.7-6.0 cm. Their fur is pale yellow with a brown tinge on the back and cream white on the ventral side. Their eyes are larger compared to other Washington species. Their large forward-pointing ears are pale and do not connect at the base (unlike Townsend’s big-eared bats). They have a long narrow tragus with a serrated outer edge.
When hunting, pallid bats may choose to not echolocate but rather use their large ears to detect sounds made by prey and glean it from the ground or vegetation. Unlike most bats, pallid bats are known to walk on the ground when they land near or on top of their prey. Pallid bats also demonstrate resistance to the venom of their prey, such as the bark scorpion.
Preferred roosts consist of rock crevices, large snags, and trees. During the winter pallid bats are believed to hibernate singly or in small groups near their summer roosts. Maternity colonies can reach up to 200 individuals. One or two pups are born from late April to July and are able to fly in 4-7 weeks. A unique maternity colony of pallid bats has long occupied a bat box located on the side of a decommissioned reactor building at the Hanford Site.
Pallid bats range from the Okanogan Valley of south-central British Columbia to Mexico. Pallid bats tend to inhabit drier regions such as deserts, canyons, coniferous forests, and shrub-steppe. Within these environments they prefer rocky outcrops and cliffs near water sources.
All species of bats in Washington state are most active from dusk till dawn. Reducing home lighting during nighttime hours will allow nocturnal species such as bats to thrive.

Silver-haired Bat (Lasionycteris noctivagans)

A silver-haired bat (Lasionycteris noctivagans) that was rescued as a pup, raised to adulthood, and is now ready for release into the wild. Flying at night in Central Washington.

The species name “noctivagans” translates to night wandering. Silver-haired bats are medium-sized bats, weighing about 8-11 g with a wingspan of 27-31 cm, and a forearm length of 3.5-4.7 cm. Their fur is made up of black and dark brown hairs tipped in silver as referenced by their common name. Their wings and tail membrane are also black. On the dorsal surface, the fur partially extends over the tail membrane. Silver-haired bats’ ears are short, round, and have a short tragus.
Foraging typically occurs through forests and intact riparian zones. Silver-haired bats’ nocturnal activity lasts for several hours after sunset and before sunrise. Short broad wings, and low-to-mid frequency echolocation, allow for slow agile flight to detect and catch small insects.
Silver-haired bats roost in trees and snags, and hide under loose bark. Wood piles, buildings, and bat houses are also used as roosts. In Washington State observations show that the
silver-haired bat population is composed of both year-round residents and migratory individuals. Maternity colonies consist of 5-25 females and their young. Gestation typically lasts 50-60 days and births of twins occur in late June and early July.
Silver-haired bats range broadly across North America, from southeastern Alaska through most of the continental U.S. and into northeastern Mexico. In Washington state, they reside in forests, riparian zones, and suburban or developed areas.
Riparian zones act as corridors for terrestrial, aerial, and aquatic wildlife. Supporting the conservation of diverse riparian habitats will help to support a balanced ecosystem.

A spotted bat (Euderma maculatum) flying at night in the Kaibab National Forest, Arizona. (1.5 miles from the edge of the Grand Canyon). This lactating female was later tracked 17 miles back to her day roost in a crevice on the vertical face of a canyon wall in the Grand Canyon National Park. It is likely she had a pup waiting to feed upon her return after a nights hunting.

Spotted Bat (Euderma maculatum)

Spotted bats are a larger species of bat in Washington state, weighing 16-20 g with a wingspan of 34-36 cm, and a forearm length of 4.8-5.4 cm. Their wing membranes are pinkish-red to gray in color. The fur on their dorsal side is black, with two distinct white spots on their shoulders, and one on their rump. Their ears are large and pink with smaller white patches of fur at the base along with distinguishable ribs stretching to the rear edge of the ear. The ears are connected at the base over the forehead and each ear has a long broad tragus.
Spotted bats use a low-frequency echolocation call that is audible to humans, unique from other bats in Washington. Spotted bats are known to forage alone and appear to use a “trap-line” strategy, returning to various sites several times a night.
Spotted bats are associated with high sheer cliffs and can crawl with ease on both horizontal and vertical surfaces. They roost predominantly in crevices along these cliffs. Little is known of their wintering behaviors; it is unclear if they hibernate or migrate. Spotted bats are thought to be solitary and do not form maternity colonies. Research suggests mothers give birth to one pup per year around mid-June to July.
Spotted bats occur in much of North America, from south central B.C. to central Mexico, with the core of their distribution in the southwestern U.S. They inhabit deserts, shrub-steppes, montane coniferous forests, and meadows with a preference for cliff-side features.
Due to the rarity of spotted bats, it is important to support further research of this species. Engaging recreational climbers to raise awareness of roosting bats could help to reduce roost disturbances and allow for reporting roost sightings.

Townsend's Big-eared Bat (Corynorhinus townsendii)

A townsend’s big-eared bat (Corynorhinus townsendii) exits a cave in the Derrick Cave complex, a series of lava tubes and lava bubbles. Dusk. Central Oregon.

Townsend’s big-eared bats were formerly known as lump-nosed bats. They are a medium-sized bat in Washington, weighing 8-14 g with a wingspan of 30-32 cm, and a forearm length of 3.4-5.5 cm. Their fur ranges from light to dark brown in color. They have two distinct lumps on each side of their nostrils, and the large ears are connected at the base above the forehead. The connected ears, larger size, and paler coloration can help to distinguish Townsend’s big-eared bats from pallid bats.
Townsend’s big-eared bats are moth specialists with slow agile flight. They use a low-frequency echolocation pulse to avoid detection of the pulse by moths. Townsend’s big-eared bats are loyal to their foraging sites around canopy gaps and forest edges and will travel up to 18 km to a specific site.
Townsend’s big-eared bats return to their roosts year after year, which consist of caves, mines, buildings, bridges, and lava tubes. During the winter they hibernate in small groups or individually in underground roosts. Maternity colonies consist of 10-250 bats and are made up of multi-generational groups of related females. Mothers give birth to a single pup from late June to late July.
Townsend’s big-eared bats range from southern B.C. throughout the western U.S. to central Mexico. They occupy a broad range of environments including coniferous and hardwood forests, riparian communities, deserts, grasslands, and agricultural areas from sea level up to 3,800 m.
Townsend’s big-eared bats are highly sensitive to disturbances of their roosts both at hibernation sites and maternity sites. By reporting roosting sites to the local fish and wildlife department, and avoiding entering them, human disturbance can be reduced and allow the bats to maintain a healthy hibernation cycle.

Western Long-eared Myotis (Myotis evotis)

A western long-eared myotis (Myotis evotis) in flight. Deschutes National Forest, Oregon. Please note: background elements (grass) have been digitally removed from this image.

The western long-eared myotis is a mid-sized myotis, weighing 5-8 g, with a wingspan of25-29 cm, and a forearm length of 3.2-4.2 cm. The dorsal fur is yellowish-brown to a darker brown color with dark brown patches on the shoulders. The ears and flight membrane are blackish and contrast with light fur. The ears and their component tragi are relatively long when compared to the size of the bat. Classification of the species, Myotis keenii, is currently under review to determine if they are the same as the western long-eared myotis or a distinct species.
Western long-eared myotis are both gleaners and aerial hunters. They use echolocation less when gleaning prey from surfaces. They have robust molars that allow them to consume hard-bodied insects like beetles. Foraging occurs around forest edges, meadows, and riparian zones throughout the night, ending two hours before daylight. Western long-eared myotis roost solitarily or in groups (ranging from 12 to 30 individuals). They can be found roosting under loose bark, in snags or downed logs, and in buildings. Little is known about their wintering behavior, but they are believed to migrate short distances to hibernate. Maternity roosts consist of 4-30 individuals. Mothers give birth to one pup per year.
Western long-eared myotis are found throughout western North America from central B.C. to central Mexico. They are found throughout Washington state in habitats that range from coniferous forests and shrub-steppe, to coastal and montane forests.
By volunteering with organizations like Bats Northwest you can help educate your community on the importance of bats to our ecosystem locally and around the world.

Western Small-footed Myotis (Myotis ciliolabrum)

A Western small-footed bat (Myotis ciliolabrum) flying at night. Sulphur Springs, high desert Washington.

Western small-footed myotis are one of the smallest bats in Washington, weighing 4-5 g with a wingspan of 24-25 cm, and a forearm length of 2.3-3.6 cm. Females of this species are often larger than males. Their fur is yellowish-brown with pale, sometimes white, fur on the undersides. Their ears are relatively long with a narrow tragus. Their ears, face mask, and wing membranes are black in color. The sharp contrast between the fur and the bare sections help distinguish them from the California myotis. Ongoing research is being conducted to determine if the western small-footed myotis should be classified as a subspecies of the dark-nosed small-footed myotis, or if they should remain a distinct species.
While foraging the western small-footed myotis are slow fliers, which allows them to be very maneuverable. Foraging occurs close to water and begins shortly after sunset. Preferred roosts consist of crevices in rock faces and cliffs, boulders in talus, beneath loose bark, buildings, bridges, caves, and mines. They are believed to hibernate during the winter within their summer range. Maternity roosts have been observed to contain up to 19 females. Mothers usually give birth to a single pup each year between mid-June and late July. Twins occur occasionally.
Western small-footed myotis live throughout western North America, from south-central B.C. to central Mexico. In Washington they are found only on the east side of the Cascade Mountains. This species resides in arid habitats such as deserts and grasslands, riparian zones, and coniferous forests.
Water sources are important to bats and other animals. Being careful not to pollute water systems that lead to rivers and lakes will keep their habitats healthy.

Yuma Myotis (Myotis yumanensis)

A female yuma myotis (Myotis yumanensis) in flight near Drake Creek in Lake County, Oregon. High-desert habitat.

Yuma myotis is a smaller species, weighing 4-6 g with a wingspan of 22-24 cm, and a forearm length of 2.6-3.8 cm. The fur of Yuma myotis varies in color from dark brown to chestnut, and even pale yellow. Their ears are short relative to their size and along with their wing membranes are pale or dark depending on the subspecies. They look like the little brown myotis, but the Yuma myotis has duller fur and slightly shorter forearms.
Yuma myotis forage where water is present and vegetation is close by. They are slow and maneuverable fliers that catch insects in the air as they move up and down waterways. Foraging begins around dusk and lasts for a few hours after sunset. Yuma myotis are opportunistic feeders that will eat whatever they can catch.
Roosts for Yuma myotis include caves, mines, rock crevices, hollow trees, buildings, and bridges. In winter they hibernate in caves, mines, and lava tubes from late October until March. Maternity colonies can consist of several thousand individuals. Birth of a single pup occurs from late May to mid-July.
The Yuma myotis is widely distributed from southeast Alaska, west to Montana, and south to western Texas and central Mexico. Yuma myotis can be found in a variety of habitats including moist and dry forests, grasslands, shrub-steppe, and deserts. Water sources are a vital feature for Yuma myotis habitats.
If you find a bat on the ground it is important that you don’t touch or pick it up with your bare hands. Several resources are available to help injured bats at batsnorthwest.org.

Photo credit for all page images: (c) Michael Durham