Meteorological Drivers of Predator-Prey Interactions in the Aerosphere

Air is an important medium for passive and active movement of numerous organisms, yet interactions among volant organisms in their aerial habitats have been poorly studied because of technological limitations to track and monitor movement behaviors in the aerosphere. Past efforts have demonstrated that predator-prey interactions among insectivorous bats and agricultural pest insects in the aerosphere can have profound impacts on agriculture and human society. We examined spatio-temporal variation in foraging dynamics of Brazilian free-tailed bats (Tadarida brasiliensis) in south-central Texas, demonstrating the potential of radar aeroecology for advancing understanding of ecological interactions in the aerosphere. Brazilian free-tailed bats disperse nightly in dense columns from cave and bridge roosts and forage at high altitudes (300 – 2500 m AGL) over large spatial scales that are easily detectable with NEXRAD Doppler weather radar (WSR-88D) installations. Understanding variation in emergence behavior of Brazilian free-tailed bats provides a model system for testing hypotheses about the influence of abiotic factors on the dynamics of group behavior. Using high resolution Level II NEXRAD radar products, we tested hypotheses about the influence of atmospheric conditions such as surface temperature, precipitation and cloud cover on timing and relative density of bat emergences to determine how atmospheric cues determine group behavior and foraging dynamics of an aerial nocturnal predator.  We investigated seasonal variation in emergence behavior and how variation in climatic conditions influence colony dynamics at broad spatio-temporal scales.  Radar visualizations have great utility for generating new hypotheses about foraging behavior of aerial species by making it possible to ‘observe’ behavior at temporal and spatial scales not previously possible.