(Left) Thermal imaging sequence showing the colony of about 250,000 free-tailed bats at Carlsbad Cavern during the first 10 minutes of emergence on 13 Sept, 2005. Occasional clusters of up to 50 bats are seen dropping from the colony. It is not clear if there is a specific organization to the emergence but bats appear to monitor the density of flying bats below the roost and take on the wing when flight conditions permit.

(Right) A close up view of the roost showing the behavior of the bats during the day. Some bats stretch their wings, others are grooming. Areas of denser clusters are warmer than ones with fewer bats. Bats that take on flight are warmer than returning individuals that are convectively cooled while flying and appear darker (colder).

Thermal colony close-up

Thermal colony emergence

(Left) A thermal imaging sequence of the full force emergence of the colony of Brazilian free-tailed bats through the main corridor of Carlsbad Cavern on Sept 14, 2007. Visible in the beginning of the video is the roost. As the camera pans around, the entrance to the cave, and exist point for the bats is seen at the end.

Thermal colony pan