Captive-Bred Crocodiles Didn't Try to Go Home After Release, Study Finds

Saltwater crocodiles bred and raised in captivity may not try to return to their breeding facility once released into the wild, a new study from Bangladesh's Sundarbans mangrove forest has found — a result that could help conservationists restore declining crocodile populations. Crocodiles are known for a strong homing instinct, often returning to their original capture sites even after being moved, which has limited the success of past relocation programs. 'What we still don't fully understand... is how this behavior plays out in individuals that have been bred or kept in captivity for long periods before being released back into the wild,' said Ru Somaweera, a behavioral ecologist at Murdoch University.

The Sundarbans is one of Bangladesh's last major refuges for saltwater crocodiles, whose numbers were severely reduced by commercial hunting until the 1970s. Despite legal protection since 1973, the population has shown no measurable recovery; the most recent survey estimated just 140 mature individuals. Researchers fitted five mature crocodiles with satellite trackers — three captive-reared females that had spent 8 to 22 years in captivity, one local wild crocodile released at its capture site, and one wild crocodile translocated far away — and monitored them for several months.

The three captive-reared crocodiles showed no sign of trying to return to the breeding facility. Instead, they settled into small, well-defined areas and moved in ways similar to the local wild crocodile that was tracked, suggesting they may adapt to a new environment. The translocated wild crocodile, named Jongra, told a different story: moved about 132 kilometers from home, it did not make it back during the study, but its movements were clearly heading in that direction, and it traveled far more each day than any other crocodile tracked, at times covering more than 30 kilometers in a single day.

'These findings suggest that releasing subadult and adult captive-reared crocodiles can be a viable strategy to strengthen wild populations,' Somaweera said, noting that the traditional approach of releasing hatchlings suffers from extremely low survival rates. For translocated crocodiles, he said, careful release planning is needed to manage their tendency to head home. The study was published in the journal Wildlife Research.