Bats use echolocation to see in the dark, but unfortunately human scientists cannot do the same.

That poses a problem for ecologists who want to know, for example, how many Brazilian free-tailed bats live in the Carlsbad Caverns of New Mexico. Researchers can't shine a light on them because that disrupts their behavior, but they can't see them without light. The answer? Infrared cameras, of course.

By installing infrared sensors, life scientist Nickolay Hristov of Winston-Salem State University and Thomas Kunz of Boston University were able to study the bat colonies in great detail from less than 50 feet away. They discovered that only something like 4 million bats live in the large colonies, an order of magnitude less [pdf] than previously estimated by visual inspection methods in the 1950s.

Beyond the science, their work also yielded tremendous video, which was posted at The Scientist. Embedded above, the team's infrared camera captured half a million bats emerging from the cave to feed at night.

The next step in this see-in-the-dark science will be taking data with multiple cameras, so that the scientists can triangulate the precise positions of the bats during flight, Hristov said.

See Also:

WiSci 2.0: Alexis Madrigal's Twitter, Google Reader feed, and green tech history research site; Wired Science on Twitter and Facebook.**