"Homing" Crocs Voyage Hundreds of Miles

Brian Handwerk
for National Geographic News
September 26, 2007

Captured and relocated saltwater crocodiles can swim hundreds of miles to return to their home rivers, according to a new study.

A team of crocodile researchers, including the late Steve Irwin, seized three crocs near bays in Queensland, Australia, and flew them by helicopter to coastal spots between 32 and 81 miles (52 and 130 kilometers) away.

In the first satellite tracking study of wild crocodiles ever conducted, researchers kept tabs on the reptiles with a transmitter attached to the back of their heads. The device collected the data and relayed it via satellite.

The data revealed that once in ocean waters, the animals covered surprising distances—between 6 and 19 miles (10 and 30 kilometers) each day.

The reptiles headed homeward following navigational cues that scientists do not yet understand.

Because of the crocodiles' speedy return home, the study also concluded that relocating "problem" animals—which favor living near people—is not an effective strategy, and that other methods of controlling them should be developed.

Super Croc

Craig Franklin, of the University of Queensland's School of Integrative Biology, is a co-author of the study, which appears in today's issue of the journal Public Library of Science.

Franklin and colleagues were particularly shocked by the endurance of a croc that was transported from one side of the northern tip of Australia to the other.

The animal simply circumnavigated the cape on a long, speedy swim home.

"It blew us away," Franklin said.

The animal spent several months roaming the coastline in various rivers, Franklin said.

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