Scientific classification

• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Infraclass: Eutheria
• Superorder: Laurasiatheria / Archonta
• Order: Chiroptera

No other mammals in the Northeast are as misunderstood as bats. A variety of myths and misconceptions surround these small, nocturnal, flying mammals. Many people think of bats as vicious animals that carry diseases and get tangled in hair. Others consider them to be friendly, cuddly animals that need only our love and understanding. Both images are somewhat misguided.

will describe the important role that bats play in our environment and will explain what to do if you find yourself sharing living quarters with them. It will also discuss the reality behind the most commonly held misconceptions surrounding these beneficial mammals.

Although some mammals are able to glide, bats are the only mammals that truly fly. That is, they actually flap their wings to propel them in flight. They belong to their own unique order of mammals, called Chiroptera, meaning “hand wing,” which refers to how the finger bones of a bat support its wings. The wings of a bat are actually thin membranes of skin that stretch between the fingers of the front leg and extend to the hind legs and tail. The bat’s finger bones are greatly elongated and serve a purpose similar to struts on an airplane wing, providing support and maneuverability during flight. When at rest, a bat folds its wings alongside its body to protect the delicate finger bones and wing membranes.

Bats live in a variety of habitats, including wetlands, fields, forests, cities, suburbs, and agricul.tural areas. They usually feed in areas where insects swarm, such as over water and agricultural fields, in forest clearings and along forest edges, and around street lights.

All northeastern bats eat insects and take their prey on the wing. Bats use their mouths to scoop small insects out of the air. Larger insects are often disabled with a quick bite and then carried to the ground or to a perch for eating. If an insect takes last-second evasive action, a bat can flick out a wing to nab the insect and draw it into its mouth. This maneuverability makes bats very efficient insect predators: A bat may consume nearly 50 percent of its body weight in insects in a single night!

Although bats can see quite well, they rely on their hearing for night flying. A highly sophisticated adaptation, called echolocation, enables bats to use their large and well developed ears to navigate and catch prey in total darkness. A bat’s echolocation system makes use of ultrasonic sound pulses and echoes to locate objects. Bats open their mouths in flight and emit a series of ultrasonic sound pulses. These pulses bounce off nearby objects— such as bushes, fences, branches, and insects—then return as echoes to the bat’s ears. Using the information gathered from these echoes, a bat can maneuver to capture an insect or avoid flying into an object. Bats have one of the lowest reproductive rates for animals their size. Most northeastern bats have just one or two pups per year, and many females do not breed until their second year. This low reproductive rate is partially offset by their long life span. On average, bats live approximately four to six years, and there are some incredible records of bats living twenty to thirty years in the wild. Most bats mate in late summer or early fall. However, the male’s sperm remains dormant in the female’s reproductive system until spring, at which time the female ovulates and fertilization occurs. The pups are born approximately six to eight weeks later, during late May and early June.

Because few flying insects are active during the winter months, bats that remain in the Northeast year-round gather in caves and abandoned mines to hibernate. Hibernation is a state of prolonged torpor during which bats greatly reduce their normal metabolic activities. Body temperature in hibernat.ing bats falls from a normal level of more than 100o F to that of the surrounding cave temperature, usually 40–50o F. The heart rate slows to only about twenty beats per minute, as compared to 1,000 beats per minute during flight. By allowing their bodily processes to slow this way, hibernating bats can survive on a very small amount of stored fat during the five- to six-month hibernation period, losing from one-fourth to one-half of their prehibernation weight.

Bats arouse from hibernation during March and usually arrive at their summer roosts in April. At this time, pregnant females seek out sheltered roosts in rock crevices, tree cavities, and tree foliage in which to rear their pups. Female red, hoary, and silver-haired bats roost alone during the summer, while females of other species gather into large or small groupings called maternity colonies. Male bats usually roost alone in fairly exposed locations.

Depending upon the species, females give birth to one to three pups in late May and early June. The pups, which are born hairless, blind, and helpless, cling tightly to their mother in the maternity roost. On summer evenings, females leave the pups in the roost and hunt insects nearby, returning often throughout the night to nurse their offspring. As the pups grow older, the females return less frequently during the night. The pups begin to fly and hunt on their own by mid-July, when they are approximately five weeks old. However, the pups will continue to nurse until they can adequately feed themselves.

Maternity colonies begin to disband in late summer and early fall. At this time, males and females of hibernating species begin to swarm together. Large groups of these bats will swarm in and out of cave entrances throughout the night, often roosting in the caves during the day. This swarming behavior brings adults together for mating, and may also teach young bats the location of the hibernation caves. Autumn also prompts the silver-haired, red, and hoary bats to begin their migration to warmer climates

Most bats in the Northeast roost in secluded locations away from humans, but two species, the little brown bat and the big brown bat, often attract attention because they repeatedly roost in buildings. These bats once roosted in hollow trees, but adapted to roosting in human structures after early settlers eliminated large expanses of forests. These ‘house bats’ situate their roosts in hot attics, which act as incubators for the growing pups.

Because they live in such close quarters with humans, unique challenges are involved in the conservation of house bats. House bats have only one or two pups per year, so the protection of their maternity colonies is important to the survival of these beneficial mammals. The destruction of just one maternity colony through chemical extermination or vandalism can have a long-term impact on the populations of both bats and insects in a local area. Unfortunately, homeowners often consider maternity colonies a nuisance and may mistakenly believe that extermination or destruction of the colony is their only solution. There is, however, a safe, humane, and effective procedure for removing a bat colony from a building. This procedure, called bat-proofing, is described in the following sections.

One way to tell if you are sharing your house with a bat colony is to simply go into the attic and look for roosting bats. During the day, bats will likely be roosting in narrow crevices in the attic walls, between the rafters, or tucked into the space between the rafters and roofing material. When you enter the attic, the bats will quickly retreat out of sight (rather than taking flight). If you can’t see them, listen for the squeaking or scurrying sounds that will verify their presence. If you are uncomfortable entering the attic when bats may be present, you can inspect the attic at night for bat droppings. The dry, black droppings are about the size of a grain of rice, and accumulate in piles below areas where the bats roost. (Mouse droppings look similar, but you would find them scattered in small amounts throughout the attic.) If you find bats living in your attic during the day, or if you find large accumulations of bat droppings, then you prob.ably have a maternity colony in your house. Sometimes, when homeowners understand the important role that bats play in controlling insects, they decide to allow the colony to remain in the attic or eaves. In this case, the homeowner must seal all openings that would give bats access into the living spaces. This safety measure is particularly important for families with small children and pets.

Bats make good neighbors. As the only major preda.tors of night flying insects, bats play an important role in controlling many insect pests. A single bat can consume as many as 500 insects in just one hour, or nearly 3,000 insects every night. A colony of just 100 little brown bats, the most abundant species in the Northeast, may consume more than a quarter of a million mosquitoes and other small insects each night.

Big brown bats, which live primarily in agricultural areas, feed on June bugs, cucumber beetles, green and brown stinkbugs, and leafhoppers. Research has shown that over the course of a sum.mer, a colony of 150 big brown bats can eat 38,000 cucumber beetles, 16,000 June bugs, 19,000 stinkbugs, and 50,000 leafhoppers and can prevent the hatching of 18 million corn rootworms by devouring the adult beetles.

The red, hoary, and silver-haired bats help to maintain forest health in the region by feeding on forest pests such as tent caterpillar moths. Because of their role in controlling insect numbers throughout the Northeast and elsewhere in the United States, the maintenance of wild bat populations is important for maintaining ecosystem health.

1. Bats of all sizes will bite in self-defense, but they almost never attack people.
2. If you must handle a bat, take precautions to minimize the chance of being bitten. By wearing leather gloves and scooping a grounded bat into a coffee can or some other container, you make it virtually impossible for a bat to bite you.
3. If you are bitten by a bat, immediately wash the bite with soap and water and see a physician. If the bat is captured, it should be killed (without destroying the head) and submitted for testing. If there is any possibility that you have been infected, the physi.cian will recommend rabies shots. Today, most people receive the rabies vaccine in a series of five relatively painless shots in the arm administered during a one month period.
4. People usually know when they are bitten by a bat. However, because bats have very small teeth, the bite is rarely obvious. Consequently, if a bat is found in the same room with a young child or mentally incapacitated person or even a very heavy sleeper, and the possibility of a bite cannot be eliminated, rabies treatment should be given.

Rabies is the most important public health hazard associated with bats, but its impact has often been exaggerated. All mammals are vulnerable to this potentially fatal disease, which is caused by a virus that attacks the central nervous system.

Animals with rabies will go through either a “furious” stage, in which they attack anything in their path, or a “dumb” stage, in which they become progressively paralyzed before death. Bats can expe.rience either of these stages, although the majority of infected bats display behavior associated with the dumb stage of rabies (Constantine 1979). Once the symptoms of rabies appear, bats usually become immobilized within two days and die within four days (Fenton 1992). The incidence of rabies in the wild bat popula.tion is low, and the spread of rabies within indi.vidual colonies appears to be very rare (Constantine 1979). Scientific surveys of wild bats in the United States and Canada indicate that the incidence of rabies in clinically normal bats is less than 0.5 percent (Fenton 1992). However, of the sick, dead, or suspect bats submitted to health departments for testing, approximately 2–5 percent test positive for rabies. Thus it is import to take precautions when handling grounded bats. Most human exposure to infected bats results from careless handling of grounded bats.

Almost everyone recognizes the need to seek immediate medical attention after an unprovoked attack by a bat (or any other animal). However, a bat lying helplessly on the ground will often arouse humanitarian instincts. The person trying to help the grounded bat may get bitten and ignore the bite, because it occurred in self-defense. Regardless of the circumstances, anyone bitten by a wild animal should immediately wash the wound with soap and water and seek medical attention. (diseases)

Of course, not all grounded bats are rabid. For example, young pups often become grounded when learning to fly. However, bats that can be caught, particularly grounded bats or bats found in unusual places, are more likely to be sick than others. Always handle all bats with leather work gloves, and warn children never to approach or pick up grounded bats. Also, cats and dogs, which come into contact with bats and other wild animals far more often than their owners, should be immunized regularly for rabies.

There is little evidence to support the notion that bats with rabies contribute to outbreaks of the disease in other wild animals (Tuttle and Kern 1981). The World Health Organization’s Expert Committee on Rabies found no evidence of natural bite transmission from insect-eating bats to carnivores (Tuttle and Kern 1981). Laboratory experiments showed that animals could be infected with rabies if they ate large amounts of infected tissue (Fenton 1992). Although the significance of this finding to animals in the wild is unknown, it again highlights the need to immunize dogs and cats.

Humans and other mammals have contracted rabies through airborne transmission, but this happened in a large southwestern cave harboring about 13 million bats. The cave’s unique conditions of high temperature and humidity, and air saturated with the bats’ saliva and urine, probably contributed to the airborne transmission of the virus (Fenton 1992). Most bat roosts do not have the right conditions for transmitting rabies through the air, and there are no records of airborne transmissions from maternity colonies living in buildings (Fenton 1992).

Histoplasmosis is an airborne disease caused by a microscopic fungus that occurs in soil and in the nitrogen-rich droppings of birds and bats (Tuttle and Kern 1981, Greenhall 1982, Fenton 1992). A dry cough and other flu-like symptoms are the usual signs of histoplasmosis, which is often mistaken for influenza. While histoplasmosis often does not produce any symptoms, severe symptoms such as high fever, problems with vision, and life-threaten.ing complications occasionally do occur (Greenhall 1982, Fenton 1992).

The fungus that causes the disease occurs naturally in soils throughout warmer regions of the world, including parts of North America (Fenton 1992). The fungus also is associated with bat droppings, called guano, which accumulates in caves where bats live in summer months. Hibernating bats do not produce guano, and therefore do not deposit the fungus in caves where they hibernate (Fenton 1992). In the eastern United States, surveys in buildings that had accumulations of guano from several colonies of big brown and little brown bats produced no evidence of the fungus causing histoplasmosis (Fenton 1992).

Homeowners should still take safety precau.tions against inhaling any particles that may contain the fungus, particularly if large amounts of bat droppings are to be disturbed in an attic. To limit the amount of airborne particles, the droppings should be vacuumed, rather than swept or shoveled. Homeowners also should use a properly fitted respirator capable of filtering particles as small as two microns in diameter to further minimize the risk of exposure (Tuttle and Kern 1981).

Bat Parasites

Like other animals, bats are hosts to a number of internal and external parasites. Most of these parasites are specialized and cannot survive away from the bats, so they pose little threat to humans and other animals (Fenton 1992). A species of bedbug, which resembles the species that feeds on humans, lives on the bats and in their roosts. However, reports of these bedbugs biting humans or domestic animals are rare. Once a bat colony is evicted from a building, any parasites that remain behind may move around the attic (and possibly the house) in search of bats. Fortunately, these parasites usually die quickly when separated from the bats.

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