Northern Prairie Wildlife Research Center
Throughout history bats have aroused the curiosity and interest of men. Bats of the United States feed primarily upon insects, many noxious. Natural bat roosts are caves and tree hollows. A few species have readily taken their abode in houses thus gaining for themselves the name of "house bats" (Allen 1962).
Bats found north of Mexico are almost entirely beneficial to man. Infrequently they become nuisances or pose public health problems. Unfortunately, most bat complaints arise from an exaggerated fear of bats, not from any actual damage; however, some form of management is justified and the type of management depends upon the problem.
Fear of rabid bats, as well as sensational and inaccurate news coverage, has engendered the use of potentially dangerous chemicals to kill bats in buildings. This may create worse public health hazards by increasing contacts between humans and sick bats, in addition to exposing people to dangerous pesticides through contact, inhalation, or ingestion of contaminated food. The conspicuous decline of bat populations, the excessive use of toxicants to kill bats in buildings, and the need for effective methods of bat management have led to the preparation of this manual. The purpose of this publication is to provide a better understanding of the biology and ecological role of insectivorous bats and to describe their occasional conflicts with people and how these may be alleviated. The present methods and practices in house bat management are reviewed and promising areas for further investigation are suggested. Special emphasis is placed on "batproofing" or exclusion as the soundest long-term solution for the management of house bats.
One of the best deterrents against house bats is to improve the energy efficiency of a house by insulation, weatherstripping, and caulking. The Internal Revenue Service (IRS) has informed the U. S. Fish and Wildlife Service (FWS) (IRS, personal communication) that these energy-conserving methods, besides lowering heating-cooling costs and providing long-term batproofing, are also eligible for a Federal residential energy tax credit as provided by the Energy Tax Act of 1978 (Public Law 95-618). In addition to the Federal energy tax credits, 43 States grant some sort of tax benefits to residents who spend money to reduce their energy use (Anonymous 1980c).
In this manual, the term "management," rather than "control," is preferred. To some, control implies the reduction of bat populations without regard for the welfare of the target species, whereas management is directed at resolving the conflict without long-term adverse effects on bat populations. Animal Damage Control (ADC) activities of the FWS are confined to the target species and applied to individuals or local populations of bats in a house, church, school, or other buildings, and do not result in long-term injurious effects. Killing bats with chemicals is unnecessary and may, in fact, create more serious health hazards than are present without lethal control.
House bat problems vary widely due to multiple types of structures, construction, materials, age, and other factors so that no single method can be recommended to solve all problems. Often a combination of methods should be employed. The recommended approach to house bat management is "Integrated Pest Management" which utilizes biological, physical, and chemical controls as well as habitat modifications (Bottrell 1979).