The Brazilian free-tailed bat (Tadarida brasiliensis) forms some of the largest aggregations of mammals known to mankind, with single caves in south-central Texas housing upwards to 20 million individuals. Although it is commonly assumed that these aerial predators feed on insect populations in both natural and managed ecosystems, relatively little is known about their population densities and nightly foraging behavior. In this three-year study, the density, composition, diet, and foraging behavior of Brazilian free-tailed bat populations in south- central Texas are being measured and modeled for use with previously published data on food habits, pesticide use, and crop production to evaluate the impact of these bats on agricultural production. Population densities and spatial patterns of foraging bats are being assessed using advanced infrared and Doppler radar imaging to provide the basic data for GIS analysis. Remote sensing methods and the resulting integrated economic model have important applications for assessing demographic and behavioral characteristics of other animal species and their economic impact on selected terrestrial and aquatic ecosystems.
