The Australian crocodile hunter, the late Steve Irwin, spent his last few months working with researchers from Australia Zoo and University of Queensland, to track saltwater crocodiles and see how far they could swim.
Using satellite technology, Irwin and his colleagues tracked three of the large reptiles, which had been relocated many kilometres from their homes in far North Queensland.
I spoke with the project researcher, Professor Craig Franklin, from UQ's School of Integrative Biology about the crocodile relocation project.
Swimming Hundreds of Kilometres Home
All three crocodiles were moved by helicopter between 52 and 130 kilometres away but still found their way back to where they had been captured and tagged.
They were tracked using a specially-designed transmitter attached to the back of their heads which collected data on their position and relayed it via satellite back to the scientists.
The reptiles were found to be swimming between 10 and 30 kilometres per day, with one crocodile swimming around the northern tip of Australia to reach home — covering more than 400 kilometres in 20 days. It had been flown across Cape York Peninsula from the west to the east coast, but succeeded in circumnavigating the peninsula to return home.
Phenomenal Ocean Swimmers
“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,” Professor Franklin said
“The data showed that crocodiles are oceanic animals which can move phenomenal distances over a prolonged period of time.”
Steve Irwin was a major driving force behind the study, and Professor Franklin said Irwin’s intellectual and logistical support complemented the knowledge, experience and contributions made by the other team members.
"He also gave us the assistance of the croc team from Australia Zoo who are highly skilled in the capture and care of crocodiles."
How Do They Navigate?
Crocodiles are often moved from waterholes and creeks in northern Australia, if they are considered to be a danger to locals or tourists to the area.
Professor Franklin said the study showed that moving problem crocodiles away to remote river systems was not effective, and some other solution would need to be found.
"Moving crocodiles to isolated waterholes which are surrounded by land might prove to be an effective impediment to them returning home."
The crocodiles probably used factors such as its position to the sun, magnetic fields, sight and smell to navigate their way back home.
“Crocodiles are more closely related to birds than they are any other reptile,” Professor Franklin said. “Maybe they are using navigation systems that are similar to what occurs in birds?”
Now that remote satellite tracking of crocodiles has proved successful, he said further satellite and acoustic tracking studies would reveal even more impressive results about crocodile behaviour, particularly about their navigation abilities.
The team's results will be published in the open access online journal, Public Library of Sciences One (PLoS ONE).
You night like to also read about Australian freshwater crocodiles in Cane Toads Kill Crocodiles
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