Tuesday, July 20, 2010

Same bats, different state

These little beauties are Brazilian Freetailed bats, more scientifically known as Tadarida brasiliensis.  I took their picture recently in the early morning as they streamed back into their home at Frio Cave in southern Texas.  They were returning from a night of fine dining on corn earworms and whatever else was flying around way up there.  There are probably a couple million bats in that cave, but we only caught about a dozen of them, roughly half males and half females, and the females were all on their way to nurse their pups.

You might remember that this same bat represented most of the calls I recorded during my research in San Francisco.  I'm now working on my PhD at the University of Tennessee in Knoxville.  I'm interested in migration, and will be focused on insect and bat migration during the fall over southern Texas.  My advisor, Gary McCracken, and others have been working on these bats and the agricultural pests they consume for some time now, but most of that research has been focused during the spring migration and summer breeding season.  We think that the insects migrate south on the cold fronts that blow down off the plains as the summer ends, and the bats find those concentrations of insects and use them to fatten up for their own migration south to Mexico.  I'll be monitoring the bats and insects during September and October for the next few years in a variety of ways, looking for clues to explain exactly what is going on up there.  I hope to also include high-altitude acoustic recording with balloons, unmanned aircraft, and NEXRAD radar imaging in future field seasons.