Crocs find way home from 400km exile

PUBLISHED : Friday, 28 September, 2007, 12:00am
UPDATED : Friday, 28 September, 2007, 12:00am

Moving rogue crocodiles to remote, uninhabited areas is useless because of the reptiles' highly developed homing instinct, Australian researchers have discovered.

Scientists were astonished to find that relocated saltwater crocodiles swam up to 400km to return to the site they were originally trapped.

The discovery of the boomerang-like instinct was made by a team of researchers that included Steve Irwin, killed last year by a stingray while snorkeling over a reef in Queensland.

The findings, detailed this week in an online scientific journal, PLoS ONE, suggest authorities must rethink how they relocate crocodiles.

Moving the reptiles could even worsen the problem, because they become upset, and possibly more aggressive, when displaced from their home territory.

'They seem to have a strong home fidelity,' said team leader Craig Franklin of Queensland University.

The scientists used satellite tracking technology to follow three crocodiles relocated in the far north of Queensland. The crocodiles were captured in the wild, anaesthetised and fitted with tracking devices.

They were then transported far from their home range and released. All three found their way back to their capture sites. Professor Franklin said he was 'staggered' by the fact that a crocodile could travel up to 30km a day.

'We often thought crocodiles tired very quickly, but here we show very clearly that they are capable of moving long distances for days on end.'

Exactly how crocodiles can navigate so well is still not known.

'Crocodiles are more closely related to birds, so maybe they are using similar navigational tools, such as magnetic fields and smell.'

The research was a collaboration between Queensland University, the Queensland Parks and Wildlife Service and Irwin's Australia Zoo.