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Bats

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Bats, our only flying mammals, are truly remarkable animals. It's too bad their unwarranted reputation as bloodsucking and disease carrying creatures has prevented many people from appreciating how beneficial and unique they are.

Bats consume thousands of nocturnal flying insects including mosquitoes, moths, and beetles, making them a more efficient insect control than birds or bug zappers. Dr. Thomas Kunz, a bat researcher at Boston University, estimates that the bats living within Route 128 eat 13 tons of insects each summer.

NATURAL HISTORY
Bats belong to the order Chiroptera, which means "hand-wing." Their wings are composed of two thin layers of skin or membrane, attached to elongated finger bones. There are four fingers and a thumb on each membrane which control the wing's movement. The thumb, located at the top of the wing, acts as a hook with which the bat is able to crawl on flat surfaces. A similar membrane stretches between the tail and hind legs.

The two most common bats found in Massachusetts are the little brown myotis (Myotis lucifugus) and the big brown bat (Eptesicus fuscus), both roost in attics, barns, and other hot, dark places.

IDENTIFICATION
The little brown and big brown bats have short, soft fur covering their head and body and, as their name suggests, both have rich brown bodies with slightly darker brown wings. The body of a little brown bat measures 4½ to 5½ inches long, including the tail, and has an 8½ to 10½ inch wingspan. The big brown bat's body ranges from 5½ to 8 inches in length with a 12 to 11¼ inch wingspan.

The most common species in rural areas is the little brown bat. During the spring and summer females of this species form colonies consisting of hundreds of individuals. Big brown bats, which prefer the more urban areas inside Route 495, are usually found in colonies of less than two hundred bats.

The other species of Massachusetts bats are: the small-footed myotis, silver-haired bat, eastern pipistrelle, red bat, and hoary bat.

FOOD
All bats found in Massachusetts are insectivores. They feed primarily at night, catching thousands of mosquitoes, moths and other night-flying insects while in flight. It is estimated that an individual bat can eat 600 insects per hour and many of these are insects that people regard as pests.

MATING
Mating takes place in the fall before hibernation and the sperm is then stored in the female's uterus throughout the winter. The eggs become fertilized when hibernation ends in the spring and in June or early July the females gather into "nursery colonies" and give birth.

YOUNG
The gestation period for both the little brown and the big brown bats is 50 to 60 days. Little brown bats give birth to one offspring and the big brown delivers one or two. As soon as the baby is born it clings to its mother, attaching itself to a nipple and, for the first few days, is carried by her when she flies at night searching for food. At three or four weeks the young begin to take short flights and catch their own food. When the young are able to feed themselves the "nursery colony" disbands to begin preparing for hibernation.

ROOSTING SITES AND BEHAVIOR
During the late spring and summer pregnant female little brown and big brown bats form large nursery colonies and roost in dark, hot places such as, attics, barns, and other outbuildings to give birth and raise their young. Males, often solitary or in groups less than a dozen in the summer, roost in cooler spots behind window shutters, and awnings and under the bark of trees.

Bats rest in these protected roost sites during the day leaving at sunset to search for food.

HIBERNATION
The nursery colonies break-up in late summer and little brown bats migrate to hibernation caves and mines, mainly in western Massachusetts, upstate New York and Vermont. Big brown bats, which are more tolerant of cold temperatures, may migrate to caves or spend the winter in the same buildings they occupy the rest of the year.

Bats choose hibernacula with temperatures between 30 degrees and 40 degrees above zero. If the temperatures drop below freezing they will move to a location with more favorable temperatures. As hibernation begins, breathing slows to one breath every five minutes and the body temperature drops until it is only slightly higher than the air surrounding it.

ECHOLOCATION
Bats are not blind as many people believe, on the contrary they have excellent eyesight, but use echolocation in the dark to detect objects as minute as a human hair. When in flight they continuously emit high frequency sounds (unheard by humans) which bounce back to their ears enabling them to locate objects, as well as the flying insects they feed on. The bat uses the increasing frequency of the echoes to zero-in on its target. During its search for food the bat may emit 10-20 pulses per second, increasing to 500 per second just before it attacks its prey.

SITUATIONS AND SOLUTIONS

Because bats are so efficient at controlling many of the insect species considered pests by humans, it is advantageous to leave them alone. Where bats inhabit buildings they are usually unobtrusive, hanging quietly from rafters during the day and exiting at night in search of food. Unlike squirrels, they are not destructive and do not gnaw on wood or wiring.

A SINGLE BAT IN A LIVING SPACE
Unintentionally, bats may enter areas occupied by humans through an open window or door, or an opening from a colonized attic or wall. A bat indoors is not necessarily a sick bat; it may be a young bat who tried to follow its mother outside and took a wrong turn or it may have followed a moth through an open window.

According to the Massachusetts Department of Public Health (MDPH) if there is a possibility that the bat came in contact with people or pets it should be captured for testing. If possible, confine the bat to one room and call the local animal control officer or a private pest control company and the MDPH at (617) 983-6800 ( 24 hrs.) for more information.

An attempt can be made to capture the bat if it lands in a spot where a coffee can
or wide mouthed jar can be safely placed over it. Slide cardboard under the coffee can, leave the bat under the container and notify the local animal control officer or police. It will be transported to the Department of Public Health Laboratory for testing.

A BAT IN CHILD'S ROOM
If the bat is found in a child's room, the child should be completely checked for signs of a bite or scratch, although a bats teeth and claws are so small the signs may go undetected. In situations involving children, immediately contact the MDPH. They may recommend that the child undergo the pro-exposure prophylactic treatment, if the bat cannot be tested.

OTHER AREAS
Confine the bat to one room by closing doors. Open windows, turn off the lights and leave the room. Hitting the bat or throwing things at it will cause it to become disoriented making it harder for the bat to find its way out.

Do not try to capture the bat unless there is the possibility it has bitten or scratched someone. Make an attempt only if the bat lands and there is no risk in placing a wide-mouthed jar or coffee can over it. Contact the local animal control officer or police department.

A BAT FOUND IN WINTER
Every now and then during the winter alive bat will be found on the ground outdoors or possibly flying around indoors. No one can assume the reason it emerged from hibernation so it is best to leave it alone and contact the local animal control officer or police to handle the situation.

WHEN TO EXCLUDE BATS
We encourage hospitality towards bats, however if there is a substantial reason to exclude them this should be undertaken only during the month of May, and from mid-August to mid-October. In between those periods young bats could be blocked inside and the decaying bodies will cause a severe odor problem.

Block openings and put one-way door in place during the day when the bats are sleeping inside.

HOW TO LOCATE AND BLOCK ENTRANCE AND EXIT HOLES

Bats leave their daytime roosting site from a half hour before sunset to a half hour after sunset. Station someone on each side of the house during that time to watch areas under the eaves, around chimney flashing and louvered vents for exiting bats. It's also wise to check these areas on a ladder for openings that the bats may not be using.

A distinctive ammonia smell in the house or attic as well as stains and droppings on outside walls of the house are also signs that bats are present. Bat droppings are dark brown, small (3/16" to 1/4" long), and are more oval than round. Once the openings have been located, block all, except one, using: ¼ inch hardware cloth (galvanized steel mesh), wood, or sheet metal.

Seal edges well, bats need only a half-inch opening to enter.

EXCLUSION
The only way to exclude bats and be sure none are blocked inside is to use a one-way door. Here are two one-way door designs from which to choose. Put in place during the day while the bats are sleeping inside and leave in place for three or four days to be sure all bats have exited.

This technique uses a flexible plastic mesh purchased at garden centers and used to protect fruit trees from birds. It is called bird netting or fruit tree netting. Cut and hang the netting so it extends 6 inches beyond the opening on all sides. Using staples or duct tape, attach the netting across the top and halfway down each side, allowing the bottom to hang loosely.

The emerging bats will be able to crawl out the bottom, but returning bats will be unable to find a way in.

Another method is to place a piece of flexible plastic or .045 inch rubber over the opening, making sure that it extends two inches beyond the hole on all sides. You want a material which will allow the bats the ability to push the covering open to exit the hole, but the covering material will fall back into place and fit tightly over the opening so the bats cannot re-enter.

BATS AND PUBLIC HEALTH

Good judgment will help eliminate the chances of humans and wildlife coming in close contact with each other.

Children should be taught never to go near or pick up a bat; any wild animal will bite when handled. Have dogs and cats vaccinated against rabies, obey leash laws, and keep cats indoors. Seal all openings in buildings which are the size of a quarter or larger to prevent bats from entering.

BATS AND RABIES
As with most mammals, including dogs and cats, bats can carry the rabies virus, but it is estimated that the number is less than one percent. Rabid bats are rarely aggressive toward humans and usually die shortly after becoming infected. According to the Massachusetts Department of Public Health, there has never been a confirmed case of bat-transmitted rabies in the state.

Rabies is a viral disease that attacks the central nervous system and once symptoms begin it is always fatal. The virus is found in the saliva of an infected animal and transmitted through a bite or scratch, or if infected saliva gets into an open cut or wound.

If you suspect someone has been exposed to rabies, wash the area with copious amounts of soap and water for ten minutes. Contact a doctor or local hospital and the state Department of Public Health at (617) 983-6800. Notify the animal-control officer or police in your community so the bat can be captured and tested for rabies.

RABIES TREATMENT
There is now an effective vaccine that can be given to a person immediately after exposure to the rabies virus which will prevent them from getting rabies. The treatment no longer requires a series of shots in the stomach and is now just six shots given over a four to six week period.

BATS AND HISTOPLASMOSIS
Histoplasmosis is a disease caused by a fungus found in soil contaminated by bat droppings (guano). Humans can be infected by breathing dust containing the spores. It is rare to find the fungus present in hot dry attics in New England. More commonly it is present in the damp caves where thousands of bats roost.

Always wear a dust mask when cleaning bat guano to prevent the inhalation of airborne spores.

BATS AND THE LAW
Relocating wildlife is illegal in Massachusetts. It is detrimental to the well-being of wildlife as well as the public. Unknowingly, sick animals may be transported and released in other locations, causing the spread of disease. Animals released in unfamiliar territory have a hard time surviving. They must compete with resident animals, and they have difficulty finding food and shelter.

It is also against state law to possess wild birds and mammals. Wildlife rehabilitators are trained and licensed by the state to care for injured and orphaned wildlife. If you need the services of a rehabilitator contact MassWildlife (Massachusetts Division of Fisheries and Wildlife ) at 508-366-4470, or Massachusetts Audubon's Widlife Information Line at 781-259-2150.

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