Bats Inside Your Home?
The 2 most common structural bats in New England are the little brown and big brown bats. The presence of bats can be detected in several ways. At dusk, when bats leave roosts to feed, they may be seen exiting through eaves, vents or from behind shutters or siding. Noise from large colonies may also announce their presence. Droppings and dark brown stains may appear near eaves and beneath entrance holes and roosts. Bat droppings (guano) are easily crushed, revealing shiny bits of undigested insects. They are never white or chalky in appearance, as are the droppings of birds.
The 2 most common bats involved in nuisance complaints are the little brown bat and the big brown bat. The little brown bat ranges from 3.1 to 3.7 inches in length and has a wingspan of 8.6 to 10.5 inches. Big brown bats range from 4.1 to 4.8 inches in length, with a wingspan of 12.1 to 12.9 inches. Big brown bats can readily be distinguished from little brown bats in flight by their larger size, slow wing beats and audible chatter.
Most colonies of bats are small and often remain unnoticed for many years. Large colonies residing in an attic or wall may become a nuisance because of noise and unsightly guano accumulations. Eviction and exclusion of roosting bats are the only safe, permanent solutions to a nuisance problem. Numerous repellents and techniques may be used in an effort to evict nuisance bats.
Bats are furred, warm-blooded mammals with body lengths of 3 to 6 inches and wingspans ranging from 8 to 16 inches. The bones in a bat’s wing are similar to those in human arms and hands. The fingers are extended and connected by leathery, elastic skin that grows from the sides of a bat’s body. Their thumbs are free from the wing membrane and have claws for grasping.
Bats have good eyesight and rely on vision for long-distance orientation. For short-distance navigation and catching food at night, they use echolocation. This sonar system helps bats, like dolphins, locate targets and background objects from the echoes of ultrasonic sounds. These ultrasonic sounds are given slowly when a bat is foraging and quicken as the bat pursues and captures an insect. Detection, pursuit and capture of an insect take about 1 second.