Rat Radar: Rodent Uses Natural "GPS"

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The mole rats lost their way less often under the altered magnetic field when they only had to travel short distances, noted Kimchi, suggesting that they switch to using the Earth's magnetic field as a reference point when navigating over long distances.

Rat Radar

While some birds, fish, amphibians, insects, and several other rodents can use the Earth's magnetic field to assess direction when they begin an excursion, the blind mole rat is the first animal to be shown to use it to regularly correct errors as it travels.

"The change in navigation strategy [over long distances] is very interesting indeed," agreed Roswitha Wiltschko, behavioral physiologist at the J.W. Goethe University in Frankfurt, Germany. Though she says that the idea that mole rats switch from an internal map to an external reference such as the Earth's magnetic field has been suggested before but not tested.

Another study by Kimchi and Terkel, published in the November 2003 issue of the science journal Animal Behaviour, shows that blind mole rats have additional radar-like abilities to detect obstacles before they come into contact with them. Another talent human hikers would kill for.

The pair found that when they blocked wild mole rats' tunnels, the animals carefully dug out the shortest route around the obstacles to reconnect them. Furthermore, they left a safe margin of 10 to 20 centimeters (4 to 8 inches) when the obstacle was a hollow ditch, but closely followed the shape of solid concrete obstacles by just 3 to 8 centimeters (1 to 3 inches). Ingeniously, when an obstacle was placed asymmetrically across the tunnel, the mole rats always detoured it on the shorter side.

The scientists believe that the animals could be using seismic waves generated by banging their heads against the earth, much like radar, to detect any dangers that lie ahead. "It's totally clear that mole rats drum their heads to communicate and have a good sense of hearing low frequency sounds," commented Pavel Nemec, zoologist at Charles University in Prague, the Czech Republic. "And it is quite possible that they use vibrations to test proximal surroundings."

"It is amazing that mole rats live in a permanently dark environment and are able to navigate so well," added Nemec. "Other animals use sight to correct their mistakes. Mole rats use the Earth's magnetic field."

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