Relocated crocodiles do a reptilian impression of homing pigeons, swimming hundreds of kilometres to get back to their old haunts (The Australian, ABC, UPI). This is bad news for those advocating relocating dangerous crocodiles that threaten humans to distant regions – they’ll probably just come back. Craig Franklin of the University of Queensland found one beast swam 400 kilometres in 20 days to get home. “We often thought crocodiles tired very quickly but here we show very clearly that they are capable of moving marathon distances for days on end,” he said (UQ press release).

Franklin and colleagues, including the late ‘crocodile hunter’ Steve Irwin, moved three large Crocodylus porosus 56, 99 and 411 km away from home. “All crocodiles spent time around their release site before returning rapidly and apparently purposefully to their capture locations,” they report in the PLOS One journal (paper, PLOS press release).

Crocodiles probably use factors such as its position to the sun, magnetic fields, sight, and smell to navigate, according to Franklin. “Crocodiles are more closely related to birds than they are any other reptile so they are possibly using navigation systems similar to birds.”

Image: Irwin and team from Australia Zoo restraining crocodile / Craig Franklin