Here we see what looks like the fall migration of Mexican free-tailed bats from Devil’s Sinkhole and Frio caves in Central Texas.
A 17 deg F drop in temp at dusk along with a 26 deg F drop in dew point seem to be the trigger.
We see them travel 100 miles SSW to the irrigated fields of Los Alamos, outside of Allende, Coahuila before they disperse.
They traveled about 116 miles in two hours, not the world speed record for mammals (99 mph) that the Frio bats hold, but not too shabby (58 mph). They seem to be headed toward Cueva de la Virgen in Coahuila, a cave historically known to hold 350,000 Tadarida and 10,000 cave myotis. We’d love to know if anyone is monitoring numbers at that cave and whether there is a big spike in numbers today and for how long. If numbers surge there, will they stay all winter, or will numbers wane as they move further south?
Austin meteorological conditions at emergence are in a chart below the video.
