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Class Mammalia Order Chiroptera

History and Biology

Bats are the only true flying mammal. They belong to the order Chioptera which means hand-winged. Their long slender finger bones act as wing struts, stretching the skin taut for flying and, when closed, fold the membrane neatly against the body.

There are about 900 species of bats distributed around most of the world. They are among the most numerous vertebrates found on land. The United States has approximately 40 species of bats, however, only a few species are problematic because of roosting in significant numbers in anthropogenic structures. The most common bats causing structural problems for humans include, but are not limited to, the following colonial species: little brown bat, Myotis lucifugus , big brown bat, Eptesicus fuscus, Mexican free-tailed bat, Tadarida brasiliensis , Yuma myotis, Myotis yumanensis , and less frequently the pallid bat, Antrozous pallidus. Blood-eating (vampire) bats are not established in the United States , they are found in Central and South America .

Bats are voracious eaters. They may consume up to a quarter of their body weight at a single feeding. Bats are insect predators and easily take their prey in flight. Feeding may occur over water, land, or some bats land and seize insects on the ground. Most bats feed at late evening, night, and early morning.

Bats' eyes are small and of limited use, but their ears are large, well developed, and adapted for sonar use. In flight, bats utter a series of high-pitched squeaks that echo off nearby objects such as branches, fences, telephone wires, insects, etc, and bounce back to the bat's ears. Bats respond to these echoes with split second reflexes that enable them to dodge obstructions and intercept insects. A bat uses its mouth as a scoop to engulf small insects and its sharp teeth to chew larger insects into tiny pieces. Bats can snare evasive insects with its wings and tail, then cradle it to the ground or perch for eating.

Most bats mate in the late summer or early fall. The sperm is stored in the female's reproductive tract until spring when fertilization occurs. Generally, female bats give birth to a single young in the summer. It is nursed by the mother until about six weeks of age. Bats make up for the low reproductive potential by being long lived. Bats have been recorded to live over 30 years. However their average life span is 9 to 10 years.

When insect populations are scarce in the winter, bats either migrate south or they hibernate. Bats are true hibernators, wintering in caves. In winter hibernation, they eat nothing, living only on stored body fat consumed slowly by a reduced metabolic rate and body temperature lowered close to air temperature.

Bats are beneficial insect eaters and may not be hunted, killed, possessed, purchased, or sold. However, bats may be moved, trapped, excluded, or killed if inside or on a building occupied by people. A person may kill or capture and transport a bat for the purpose of laboratory testing if there is a rabies concern.

Public Health Damage:

Bats are beneficial insect eaters. However, they may cause problems in groups of large numbers around structures. Bats and their droppings, guano, create a serious and constant health problem. They may be a reservoir for the transmission of diseases to humans (zoonotic diseases) such as rabies, several forms of encephalitis, histoplasmosis, Chagas' disease, and endemic relapsing fever. In additional to the numerous infectious zoonotic diseases, Bats also harbor and transmit a number of ectoparasites associated with the mammal and its nests such as lice, mites, fleas, ticks, and bugs.

Structural Damage:

Bats may roost in large numbers thereby defacing equipment, and buildings with excretory droppings. They foul areas where people may live and/or work. When bats roost inside structures, particularly attics, chimneys, or hollow spaces between walls and floors, their guano and urine may cause a persistent stench that is unbearable to humans. Moisture from urine and guano can penetrate wallboard and ceilings and stain the interior surface. In some situations removal and replacement of affected materials is the only solution. Sometimes guano removal can be dangerous and expensive.

Agricultural Damage:

Bats threaten the health of livestock in United States agriculture because they may be a reservoir for the potential transmission of many livestock diseases in concentrated livestock production facilities. Additionally, seed, grain, meat, vegetable, and fiber agricultural products can be contaminated by bat droppings from bats inhabiting production and warehouse facilities.

Environmental Damage:

Bats are voracious consumers of insects and benefit the environment in that respect. However, because of their potential to roost in human structures, caves, and caverns, and their potential production of guano and urine, bats are a serious and constant public health and property damage problem.

Economic Damage:

Bats do help control insects economically and are beneficial in that respect. However, they do have potential for damage to public health, the environment, and the economy. Economic damage from Bats is difficult to assess when you consider the intangible costs of the impact of zoonotic diseases on the public health of humans, livestock, and wildlife. Additionally, it is also difficult to determine the real cost of structural and park damages from defacement by guano and urine. Human food may become contaminated in food processing and warehouse facilities by guano from bats inhabiting the buildings or from insects, arthropods, and rodents that live in the guano deposits. Bat droppings are considered a food contaminant by consumers, the Food and Drug Administration, and USDA, and corrective measures must be taken.

References:

Coded Federal Registry, 50CFR17.Subpart D, Endangered and Threatened Wildlife an Plants

Coded Federal Registry, 50CFR 20.43, Wildlife and Fisheries, Hunting and Migratory Bird Regulations

Coded Federal Registry, 50 CFR 21.43 Subpart D, Control of Depredating Birds

Fergus, C., 2000, Wildlife of Pennsylvania and the Northeast, Stackpole Books, Mechanicsburg , PA 17055

Mallis, A. 1997. Handbook of Pest Control: The behavior, Life History, and Control of Household Pests, Eighth Edition. Mallis Handbook and Technical Training Company.

Oklahoma Wildlife Conservation Commission, 2004-2005, Oklahoma Hunting Guide, Protected Species. Page 9. Oklahoma Department of Wildlife Conservation, P.O. Box 53465 , Oklahoma City , OK 73152 .

Texas Parks and Wildlife Department, 2004, Hunting and Fishing Regulations, Endangered, Threatened, and Other Protected Nongame Species, Protected and Unprotected Birds, Texas Parks and wildlife, 4200 Smith School Road, Austin, Texas 78744.