Crocs make epic journey home
One of the crocodiles travelled 411km home
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Thursday, 27, Sep 2007 12:59
Three crocodiles taken up to more than 400km from their native habitat in Australia have managed to return home, scientists have reported.
The creatures were captured on the Nesbit and Wenlock rivers on the Cape York Peninsula, North Queensland, and tagged with satellite transmitters.
Secured in nets, the crocodiles were then flown by helicopter to new locations which would take between 56 and 411km to return to their former locations.
All three behaved similarly after release, each making apparently random movements around their new site for between ten and 108 days.
The researchers say this time period could have let the crocodiles take in local signs and work out the direction of travel required.
Each crocodile then took the most direct route back to their capture site; once there they showed no inclination to leave, remaining there for the remainder of the tracking period.
It took one of the crocodiles 20 days to cover 411 km of coastline, during which he rounded the tip of the Cape York Peninsula. Figures show he often travelled more than 15km per day.
Writing in PLOS One, scientists behind the project say the journeys of the animals were both "purposeful and direct".
"All returned to the same place at which they were captured, and none travelled any distance in an inappropriate direction, except for a brief excursion southwards by crocodile C, the most disrupted individual," they said.
"Was this movement associated with an assessment of the correct direction home? Our observations clearly imply that crocodilians are skilful at interpreting a suite of complex cues for orientation and navigation, and this aspect of their behaviour demands additional investigation."
The researchers conclude that their findings show relocating crocodiles away from humans is "very likely to be ineffective".
"If a problem crocodile animal is living in an area where conflict with humans is likely, then other options need to be employed."