Ohio is home to a variety of bat species, all of which are insectivores that play a beneficial role in the state’s ecosystem. These nocturnal mammals help control insect populations, including many agricultural pests, as they forage after sunset. The state’s diverse geography, from dense forests to urban environments, supports several distinct types of bats throughout the year.
Common Bat Species and Identification
The Big Brown Bat (Eptesicus fuscus) is one of the species most frequently encountered by Ohio residents, often utilizing buildings for summer roosts and winter hibernation. This medium-to-large bat has a wingspan of about 12 to 13 inches and features glossy, dark brown fur with black ears and wings. It is notably robust and feeds primarily on hard-bodied insects like beetles.
Other common species are categorized as migratory tree bats, which are typically solitary and roost in foliage rather than structures. The Eastern Red Bat (Lasiurus borealis) is easily identified by its unique brick-red fur, often with a frosted appearance, and a fully furred tail membrane. The Hoary Bat (Lasiurus cinereus), Ohio’s largest bat with a wingspan up to 15.5 inches, has dark brown fur tipped with white, giving it a distinctive silver-gray or “hoary” look. The Silver-Haired Bat (Lasionycteris noctivagans) is smaller, characterized by its dark black fur with silver-tipped hairs, and prefers to roost under loose tree bark or in tree cavities.
Federally Protected Bats and White-Nose Syndrome
Several Ohio bat species face severe population threats and are protected under the federal Endangered Species Act (ESA). The Indiana Bat (Myotis sodalis), federally listed as endangered, is a small, dark-brown bat that depends on specific cave temperatures for winter hibernation. The Northern Long-Eared Bat (Myotis septentrionalis), also federally protected, is distinguished by its long ears and prefers to roost in tree cavities during the summer.
White-Nose Syndrome (WNS) is the primary cause of steep declines in these hibernating populations. WNS is caused by the fungus Pseudogymnoascus destructans, which grows on the muzzle and wings during winter torpor. The irritation causes bats to wake up more frequently, prematurely depleting the fat reserves needed to survive the winter. Since its arrival in Ohio, WNS has caused mortality rates of 90 to 99 percent in cave-dwelling species.
The Tri-Colored Bat (Perimyotis subflavus), formerly known as the Eastern Pipistrelle, is another small species that has experienced catastrophic declines due to WNS. This bat features distinctive tricolored fur, with bands of dark, light, and dark coloration along each hair shaft. Federal agencies are proposing to list the Tri-Colored Bat as endangered under the ESA, which prohibits activities that disrupt its habitat or hibernation sites.
Habitats and Seasonal Activity
Ohio bats exhibit distinct seasonal behaviors, dividing them into species that hibernate locally and those that migrate south. Cave-dwelling bats, including the Big Brown Bat and the federally protected species, overwinter in structures called hibernacula, such as caves or abandoned mines. During hibernation, which typically runs from late October to early April, bats enter a state of torpor to conserve energy.
In contrast, tree-roosting species like the Hoary Bat and Eastern Red Bat migrate to warmer southern climates for the winter months. Mating for many species occurs in the fall through a process called “fall-swarming,” often near hibernacula entrances. Females store the sperm through a mechanism called delayed fertilization, with actual conception occurring after they emerge from hibernation in the spring. Pregnant females then form maternity colonies in summer roosts, giving birth to a single pup in late May or June.
Coexisting Safely with Bats
A small fraction of bats can carry the rabies virus, making it necessary to avoid all direct contact with the animals. A bat found on the ground or acting erratically during the day is likely sick and should never be handled without specialized protective gear. If a bat is found in a room with a sleeping person, an unattended child, or someone mentally impaired, immediate medical consultation is necessary, even if no bite is apparent.
The bat should be safely captured for rabies testing by contacting the local health department. When bats take up residence in a structure, their removal is regulated by state law. Exclusion, the only legal method, involves installing one-way devices that let bats leave but prevent re-entry. Exclusion is prohibited during the state’s maternity season, which is legally defined as May 16th through July 31st, to prevent the entrapment of flightless young inside the structure. Exclusion should occur outside of these summer months and the winter hibernation period.