Resource: Maryland’s Native Bats

This is a resource for our blog post about International BatWeek:
Why we love bats (And you should, too.)
And a project-in-progress:
How to Support Bats in Your Backyard

Maryland’s Native Bats & Their Habitats

Each Bat name is linked to a brief description and habitat requirements, along with random interesting facts we’re finding as we learn about Maryland’s native bats and how we can support them in our backyard habitats.



Tree Bats	Cave Bats
Eastern red bat Lasiurus borealis	Eastern Small-footed Bat Myotis leibii
Hoary Bat Lasiurus cinereus	Little Brown Bat Myotis lucifugus
Silver-haired Bat Lasionycterus noctivagans	Northern Long-eared Bat Myotis septentrionalis
Evening Bat Nycticeius humeralis	Indiana Bat Myotis sodalis
	Tri-colored bat Perimyotis subflavus
	Tri-colored bat Perimyotis subflavus
	Big brown bat Eptesicus fuscus
Unconfirmed in Maryland: Seminole bat Lasiurus seminolus and Southeastern bat Myotis austroriparius

Eastern Red Bat Lasiurus borealis Conservation Threats: Listed as ‘least concern’ but are second largest group (after Hoary Bats) of bats killed by wind turbines.
Description		Weight: 1/4 – 1/2 oz. \| Body length: 2 1/8 in. \| Wingspan: 11 – 13 in. Males: Brightly colored red and orange Females: Slightly duller and lighter in appearance. Both: Wings are long and pointed. Densely furred. Tail membrane is fully furred. White patch of fur on shoulders and wrists.
Food		Moths mainly, plus crickets, flies, mosquitoes, true bugs, beetles, cicadas, and other insects. Heroic agricultural pest eaters: gypsy moths, tent caterpillar moths, Cydia moths, Acrobasis moths, cutworm moths, and coneworm moths
Water		Drinks fresh water daily.
Shelter		SUMMER: Solitary and often roost among leaves in trees. Preferred roosts are most likely to be south facing, deciduous trees, 4-10 feet off the ground. WINTER: Very little is known about their winter behavior or habitat. In Maryland, eastern red bats migrate south or or go through short term periods of inactivity known as torpor. They typically seek out leaf litter or hollow trees for shelter during torpor. Occasionally, on a warm winter day, eastern red bats can be seen in flight.
More Facts about Eastern Red Bats		The Eastern Red Bat is our most common tree bat. They can fly up to 40 miles per hour! Red bats are solitary, coming together only to mate and to migrate. A female Red Bat will even roost by herself when rearing young. Unlike most bats, she might also give birth to twins — or even up to a litter of five! Hibernating Red Bats can adjust their metabolic rate to survive body temperatures as low as 23 degrees F.
Where to See Them		Are you sure that’s a dead leaf or a pinecone clinging to the tree branch? Look again! It could be an Eastern Red Bat! Their bright coloring actually turns out to be good camouflage! Eastern Red bats are some of the earliest evening fliers. If you’re not bat-watching around the edge of a wooded area, you could possibly see them flying around your street-light hunting for moths.
Will They Roost in Bat Boxes?		More likely to nest in a secluded area away from humans.
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Hoary Bat Lasiurus cinereus Conservation Threats: In Maryland, listed as ‘species of greatest conservation need’. Hoary Bats make up 40% of bats killed by wind turbines—estimated to be over 128,000 each year.
Description		Weight: 0.92 oz. \| Body length: 5.1 to 5.7 in \| Wingspan: 15.5 in. Males: Females: 40% bigger than males Both: Fully furred tail membrane. Long, dense fur is distinctly banded with blackish, brown, or tan colors at the base and white “frosting” at the tips giving the bat a hoary appearance. The fur around the throat and forehead is yellow.
Food		Moths, true bugs, mosquitoes, other insects.
Water		Drinks fresh water daily. Hunts aquatic insects over lakes.
Shelter		SUMMER: Solitary. Typically roost 7-20 feet above the ground in coniferous tree, often near cleared areas. WINTER: In Maryland, Hoary Bats migrate south for the winter to subtropical, even tropical habitats to hibernate in coniferous trees.
More Facts about Hoary Bats		With a wingspan of up to 16 inches, the Hoary Bat is the largest bat in Maryland! Hoary bats have a swift and direct flight which coupled with their size makes it somewhat easy to distinguish in flight. The bats can cover 24 miles while foraging! Among the most widespread of all bats, found throughout most of Canada and the United States and south into Central and South America. The hoary bat is Hawaii’s only native land mammal. Stray individuals have been found from Iceland to Orkney Island as well as in Bermuda and the Dominican Republic.
Where to See Them		Look 10-15 feet up in trees along forest borders. Hoary Bats prefer woodland, mainly coniferous forests, but hunts over open areas or lakes. They don’t emerge to feed until after dark.
Not Bat Box Roosters		A Hoary Bat will normally roosts alone on trees, hidden in the foliage, but sometimes they are seen in caves with other bats. They are not attracted to houses or other human structures, and they stay well-hidden in foliage throughout the day.
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Silver-haired Bat Lasionycteris noctivagans Conservation Threats: In Maryland, listed as ‘species of greatest conservation need’. Silver-haired Bats are the second largest group (after Hoary Bats) of bats killed by wind turbines.
Description		Weight: 1/4 – 1/2 oz. \| Body length: 2 1/8 in. \| Wingspan: 11 – 13 in. Males: Females: Both: Medium sized, predominantly black with hair that’s white tipped. Their fur is only lightly haired. Black wings.
Food		Heroic agricultural pest eaters! Small, soft-bodied insects, like flies, midges, leafhoppers, moths, mosquitoes, beetles, crane flies, lacewings, caddisflies, ants, crickets, and occasional spiders.
Water		Drinks fresh water daily. Hoary Bats will forage low, over both still and running water.
Shelter		SUMMER: Typically not found in MD during summer. Roost under loose bark, in rock crevices, in clumps of leaves, in woodpecker holes, and sometimes in open sheds, garages or outbuildings. WINTER: Generally migrate south, but occasionally will stay and spend the winter under loose bark, in rock crevices, in clumps of leaves, in woodpecker holes, in bird nests, sometimes open sheds, garages or outbuildings.
More Facts about Silver-haired Bats		Silver-haired Bats fly like Sunday drivers: slow and leisurely, but fairly maneuverable. They will also sometimes hunt together in groups.
Where to See Them		highly dependent upon Old Growth forest areas for roosts,
Not Box Roosters		Silver-haired Bats are highly dependent upon Old Growth forest areas for roosts in tree cavities or small hollows.
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Evening Bat Lasionycteris noctivagans Conservation Threats: In Maryland, listed as ‘species of greatest conservation need’.
Description		Weight: 1/4 – 1/2 oz. \| Body length: 3 – 3 7/8 in \| Wingspan: 10-11 in. Males: Females: Both: Small bat with dark brown fur that is tipped with light gray, and black on its ears, wings, and tail. Evening bats have relatively short ears and wide dog-like muzzles.
Food		Beetles mostly, also flies and flying ants. Small nocturnal insects including flying ants, spittle bugs, June beetles, Japanese beetles and moths. Agriculture Pest Hero: Spotted cucumber beetles. Evening bats will “partition” (differentiate to not compete) their food sources with other bats in their range.
Water		Drinks fresh water daily.
Shelter		SUMMER: Large colonies in buildings, or in smaller colonies under loose bark or within hollow trees. WINTER: Mysterious! The winter habits of evening bats are relatively unknown. It is thought that they may migrate south during the winter and remain active, but some may hibernate in hollow trees or under bark in Maryland.
More Facts about Evening Bats		Evening Bats maternity colonies can get pretty large, with several hundred individuals. Evening bats have a pungent odor! They’re medium to fast flyers with erratic flight patterns but will occasionally fly slow. Their lifespan tends to be shorter than other species of bats.
Where to See Them		True forest bats! Female bats return to the roost where they were born to give birth
Not /Box Roosters?
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Eastern Small-footed Bat Myotis leibii Conservation Threats: Dramatically declined in number in Maryland, due to White-nose Syndrome. In Maryland, listed as ‘species of greatest conservation need’ and ranked as ‘highly endangered’ and ‘highly state rare. Main threat is habitat disturbance. Conservation efforts are more difficult as their roosting locations are mysterious.
Description		Weight: 0.1 – 0.2 oz. \| Body length: 2 7/8 -3 1/4 in. \| Wingspan: 8-10 in. Males: Females: Both: Mostly golden brown in color and have a black facial mask and ears. Fur is dark at the roots, and fades to a light brown at the tips, which gives the bats a signature shiny, yellow-brown appearance.
Food		Heroic mosquito eaters! Capable of filling their stomachs in an hour! Small, soft-bellied prey like, flies, mosquitoes, true bugs, beetles, ants, and other insects
Water		Drinks fresh water daily. Will forage over streams and ponds. Females roost closer to ephemeral water sources than males.
Shelter		SUMMER: Eastern small-footed bats spend summer days roosting in rock crevices, under boulders, in quarries, and very rarely in buildings. WINTER: Hibernates in cold, dry areas near cave entrances (drafty, low humidity, may be subfreezing).
More Facts about Eastern Small-footed Bats		Among the smallest of North American bats. Flies slow and erratically from 3- 10 feet off the ground. This is probably why Eastern Small-footed bats are the last to begin hibernation, often the first to leave, by February or March. Very low levels of light, noise and heat are sufficient enough to wake hibernating bats. Once awoke the bats begin to expend energy and deplete critical fat reserves. If these disturbances are repeated bats, especially juveniles become very susceptible to death. Due to their dependency on rare ecological features where they nest they are at particularly high risk from human endeavors like mining, quarrying, oil and gas drilling and other mineral extraction. Also vulnerable due to agricultural, industrial and residential development. Has a very slow reproduction rate, another reason it’s in so much danger.
Where to See Them		They’re nighttime foragers. Wild, heavily forested, mountain regions, frequently but not exclusively in caves in hemlock forests. They are known from hemlock forest habitats and from rock falls, caves, mines and rock crevices associated with hemlock forest regions. They prefer to hibernate in caves and mines that are very short in length. Because they hibernate individually, or in groups of less than 50, and have also been found hibernating with other species of bats, documenting info about them has been difficult.
Not Box Roosters		Will not usually use bat boxes like many other bat species, due to their tendency to nest alone or in very small groups
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Little Brown Bat Myotis lucifugus Conservation Threats: Dramatically declined in Maryland, due to White-nose Syndrome. In Maryland, listed as ‘species of greatest conservation need’ and ‘highly state rare’. Vulnerable to a number of predators when they are packed together in hibernation. Pesticides can kill them.
Description		Weight: 1/4 – 1/2 . \| Body length: in. \| Wingspan: in. Males: Females: Both: Small bat, glossy tan to dark brown. Fur is uniformly dark brown and glossy on the back and upper parts with slightly paler, greyish fur underneath. Has relatively large feet with long hairs that extend past the toenails.
Food		Heroic mosquito and agricultural pest eaters! Mosquitoes, gnats, midges, mayflies, crane flies, beetles, wasps, moths.
Water		Drinks fresh water daily. Forage over water where their diet consists of aquatic insects, mainly midges, mosquitoes, mayflies, and caddisflies. They prefer to roost near water. and move in and out of adjacent vegetation.
Shelter		SUMMER: Often roost in buildings, mostly hot dry attics but sometimes beneath tar paper, under shingles, behind shutters or siding. They also will occasionally use bat houses. They may have differents roosts for day and night during spring and summer. WINTER: True hibernators. Little brown bats often use caves or mines for winter roost sites. Little brown bats hibernate as a community in the winter, with one roost (outside of Maryland) reportedly having over 300,000 bats packed together for warmth!
More Facts about Little Brown Bats		Little Brown Bats have been ‘model organisms’ in the study of bats (chiropterology). A Little Brown Bat can catch up to 1,200 insects in just one hour. Little brown bats can live up to 34 years! They echolocate to find their prey. They are particularly good at hunting insects when they are at close range and packed together. Capture prey both by gleaning and by catching them in the air. When in flight, bats scoop up the prey with their wings, while prey above water is directly grabbed with the mouth.
Where to See Them		leaves its roost at dusk and the next two or three hours are peak activity periods. They are also active before dawn. This species is especially associated with humans, often forming nursery colonies containing hundreds, sometimes thousands of individuals in buildings, attics, and other man-made structures. On warm winter days, above 50 degrees, Little Brown Bats may emerge to feast on insects. Evening forages are done in groups and above the water.
Potential Box Roosters		Little Brown Bats are heavily dependent upon roosts which provide safe havens from predators that are close to foraging grounds. Nursery roosts are in natural hollows and buildings (or at least close to them). They have been found under the sheet metal roofs of trappers’ caches[5] and attics of buildings. Night roosts tend to be in the same buildings as day roosts, but these roosts tend to be in different spots that are more constrained; the bats pack together for warmth. Bats rest in night roosts after feeding in the evening which may serve to keep their feces away from the day roosts and thus less noticeable to predators.
< Back to Maryland Bat List
Northern Long-eared Bat Myotis septentrionalis Conservation Threats: The US Fish and Wildlife Service listed the species as Threatened under the Endangered Species Act in April 2015. Dramatically declined in Maryland due to white-nose syndrome. In Maryland, listed as ‘species of greatest conservation need’ and ‘highly state rare’.
Description		Weight: 1/8 – 1/4 oz. \| Body length: 3 – 3 7/8 in \| Wingspan: 9-11 in. Males: Females: Both: Dull brown fur with a slightly paler belly. Long ears that would extend well beyond the muzzle (nose) if laid flat.
Food		Heroic agricultural pest eaters! Focus on moths, but also eat beetles, flies, and other insects. They glean from the service rather than capture prey in flight.
Water		Drinks fresh water daily.
Shelter		SUMMER: Buildings, hollow trees (both alive and dead), behind shutters, under loose bark, and under shingles. WINTER: Caves and mines. Within these areas, often roost in cracks and crevices.
More Facts about Northern Long-eared Bats		Northern Long-eared Bats are gleaners—capable of picking up insects like katydids off of vegetation. A relatively longer tail and larger wing area give them increased maneuvrability during slow flight.
Where to See Them		Dense forest stands. Long-eared Bats are active one to two hours after dusk and then again right before sunrise. begin feeding after dusk and often carry larger prey to their night roosts for consumption.
Not /Box Roosters?		generally more solitary and is most often found singly or in very small groups. Chooses maternity roosts beneath exfoliating bark and in tree cavities
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Indiana Bat Myotis sodalis Conservation Threats: One of the first bat species in the United States to be recognized as endangered by the U.S. Fish and Wildlife Service Endangered Species Act. Maryland, listed as ‘species of greatest conservation need’. The Indiana bat experienced a nationwide 57% population decline from 1960 to 2001 White-nose Syndrome has devastated the Indiana Bat. Estimated that 95% of Pennsylvania’s entire cave bat population is gone. Higly vulnerable to predators as they aggregate in large numbers. Human disturbance and the degradation of habitat are the primary causes for the decline.
Description		Weight: 1/8 – 1/4 oz. \| Body length: 3 – 3 5/8 in \| Wingspan: 9 – 11 in. Males: Females: Both: Dull, wooly fur is distinctly banded, band nearest the body is dark, gray middle, cinnamon-brown tip. Nose is pink to brown. Wing membranes blackish-brown. Hair on feet is short and does not extend beyond claws.
Food		Heroic agricultural pest eaters! Moths, beetles, mayflies, soft and hard-bodied insects
Water		Drinks fresh water daily. Roost proximity to water is highly variable and therefore probably not as important as once thought. Ponds, streams, and road ruts appear to be important water sources, especially in upland habitats.
Shelter		SUMMER: Hollow trees, under loose bark, sometimes in buildings. WINTER: Caves or mines.
More Facts about Indiana Bats		In winter, the largest hibernating populations of Indiana myotis occur in just three states: Kentucky, Missouri, and Indiana, where they form large, highly vulnerable aggregations.
Where to See Them		Primary roosts in canopy gaps and forest edges that receive direct sunlight throughout the day. Alternate roosts are generally in the forest interior with little or no direct sunlight.
Not Box Roosters		Indiana Bats seem to have preferences for hardwood trees that are dead or dying with exfoliating bark. Indiana Bats are frequent roost switchers. Maternity colonies appear to have at least one “primary roost” that is used by the majority of the colony. Over a dozen different “alternate roosts” may be used by portions of the colony intermittently. The switching may be because of a need to regulate temperature during reproduction or due to environmental changes.
< Back to Maryland Bat List
Tri-colored Bat Perimyotis subflavus Conservation Threats: Tri-colored bats have dramatically declined in Maryland due to white-nose syndrome. In Maryland, listed as ‘species of greatest conservation need’ and ‘highly state rare’.
Description		Weight: 1/5 oz. \| Body length: 2 3/4 – 3 3/4 in. \| Wingspan: 8-10 in. Males: Females: Both: distinct tri-colored fur that appears reddish-yellowish-brownish and is dark brown at the base, pale in the middle and dark at the tip. Forearms are orange-to-red and wing membrane is black.
Food		Moths, beetles, true bugs, mosquitoes, ants and other insects. Heroic agricultural pest eaters! Have been know to feed on grain moths hatching from corn cribs
Water		Drinks fresh water daily.
Shelter		SUMMER: clumps of leaves and sometimes in open houses and buildings. WINTER: caves, rock crevices, and mines.
More Facts about Tri-colored Bats		The Tri-colored Bat is the smallest bat found in Maryland. It’s also the only bat in Maryland with three colored fur. Tri-colored Bats do not tolerate freezing and are the first to enter hibernation and the last to leave the cave in the spring. They also have strong roost fidelity! Tri-colored bats will return to the exact same spot in a cave or mine from year to year. Because they choose to hibernate deeply in caves or mines with warm, stable temperatures, White-nose Syndrome is suspected to be the cause of their serious decline.
Where to See Them		Tri-colored bats seem to prefer edge habitats near areas of mixed agricultural use. Among the first bats to emerge at dusk. Look for them at tree-top level. Their foraging behavior is still mostly a mystery.
Not /Box Roosters?		Females form maternity colonies that are no bigger than 20 bats, whereas the males roost alone during summer. Their colonies tend be in foliage where they receive a lot more sunlight than other bat species.
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Big Brown Bat Eptesicus fuscus Conservation Threats: In Maryland, listed as ‘species of greatest conservation need’. Dramatically declined due to White-nose Syndrome, but currently on the rebound!
Description		Weight: 1/2 – 5/8 oz. \| Body length: 4 – 5 1/8 in. \| Wingspan: 13-16 in. Males: Females: Both: Large, brown overall. Large face with short, round ears. Belly tends to be lighter in color. Wings tend to be black.
Food		Heroic agricultural pest eaters! They consume significant crop and forest pests including ground beetles, scarab beetles, cucumber beetles, snout beetles and stink bugs, in addition to numerous species of moths and leafhoppers. In general, prodigious quantities of a wide variety of night-flying insects. Beetles, ants, flies, mosquitoes, mayflies, stoneflies, and others.
Water		Drinks fresh water daily.
Shelter		SUMMER: Buildings, under bridges, in hollow trees, beneath loose bark, and behind shutters. They also will occasionally use bat houses. WINTER: Buildings, caves, and mines.
More Facts about Big Brown Bats		Big Brown Bats are probably America’s most beneficial animal. Big Brown Bats are vital players in the checks and balances of insect pests. Females can consume their weight in insects every night. This adds up in a hurry and makes a significant impact. A colony of 150 bats consuming adult cucumber beetles all summer, which prevents 600,000 fewer egg-layers, which then prevents 33 MILLION of their larvae– a major pest of corn. Big Brown Bats have been found to live up to 19 years in the wild. That means a colony of 150 bats, even with the average life expectancy of 7 years, would have prevented over a quarter of a BILLION root-worms during their lives. Not to mention the 600,000 cucumber beetles, 194,000 scarab beetles, 158,000 leafhoppers, and 335,000 stink bugs per year,
Where to See Them		Although our human developments have forced them out of their natural habitats, Big Brown Bats are capable of coexisting with us in our urban, suburban, or rural environments. They are generalists in their foraging behavior, too. They showing no prefernce for feeding over water vs. land, or in forests vs. clearings.
Will Roost in Bat Boxes		As Big Brown Bats move into closer contact with us, roosting in our attics, buildings and other man-made structures, bat-specific artificial roosts are a healthy compromise to help us coexist together. Bats stay out of our houses, but are close enough to help us out with insect pest control.
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