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Tiny GPS unit tracks bats

Asaf Tsoar of the Hebrew University of Jerusalem and the daughter of Prof. Ran Nathan hold one of the bats used in the study of how these mammals are able to
Asaf Tsoar of the Hebrew University of Jerusalem and the daughter of Prof. Ran Nathan hold one of the bats used in the study of how these mammals are able toThe Hebrew University of Jerusalem

Tiny and lightweight GPS units are giving researchers a new way to track small critters, a breakthrough that could open our eyes anew on the mysterious wonders of nature.

For example, a team of Israeli researchers recently outfitted Egyptian fruit bats with GPS units that weigh less than a half ounce (10 grams) to gain clues on how the free-ranging mammals find their way around each night to feed at specific trees, often dozens of miles away from their caves.

The units consist of a GPS receiver that is smaller than a penny coupled with a data logger that weighs 8 grams. The data is downloaded upon recapture, or wirelessly up to 500 meters away.

The tiny GPS units allowed the researchers to step outside the lab and conduct experiments in the complex landscape the animals navigate on a nightly basis.

Their findings show the mammals carry around an internal cognitive map of their home range based on visual landmarks such as lights or hills, according to a paper in the August 15 in Proceedings of the National Academy of Sciences.

"Although lab experiments based on distances of a meter or two had hinted at the existence of an internal map for navigation, this study is the first to show that such mammals as fruit bats use these maps to find their way around areas 100 km in size," notes a press release on the study.

This is far from the first use of GPS to track wildlife. Collars outfitted with the technology are routinely used to study larger animals, including coyotes, jaguars and polar bears.

GPS technology is also used to track students who skip class, sex offenders, and, secretly, the cars of citizens.

But as the systems get smaller, smaller animals can be studied with GPS, which might be easier than the currently available radio transmitters used to track the movements of critters such as dragonflies and songbirds.

More stories on wildlife tracking:

John Roach is a contributing writer for msnbc.com.