Crocodiles are famous for finding their way home. These ones didn’t.
A recent study shows that saltwater crocodiles raised in captivity can adapt to life in the wild more successfully than anticipated, remaining in their release locations rather than attempting to return to the breeding facility where they were born. This discovery points to a promising new approach for rebuilding endangered populations.
The Homing Instinct That Failed
The common belief is that crocodiles can find their way back home, which explains why they return to their original capture locations and limit the success of relocation efforts. This idea held true for the translocated wild crocodile named Jongra. The captive-raised crocodiles, however, did not follow the same path.
Behavioral ecologist Ru Somaweera, an adjunct associate professor at Murdoch University, explained the stakes. “If crocodiles who are bred and raised in captivity subsequently return to their enclosures or breeding facilities after being released, attempts to reintroduce them into the wild as part of conservation efforts will ultimately fail.”
A Long History Of Decline
Researchers conducted their work within the Sundarbans mangrove forest in Bangladesh, which remains one of that nation’s few remaining strongholds for saltwater crocodiles. Intense commercial hunting for crocodile hides greatly reduced the species in Bangladesh until the 1970s. Legal protection has been in place since 1973, yet the population has not measurably recovered.
The vast majority of the nation’s remaining known crocodiles reside within the Sundarbans. That population is tiny, with the latest survey putting the count of mature individuals at no more than 140.
How The Study Worked
Five adult saltwater crocodiles were followed with satellite trackers. Among them were three females that had lived 8-22 years in captivity, plus one local wild crocodile that was taken in and set free at the same place. The fifth was a wild crocodile that had been brought from far away from where it was first caught.
The scientists then followed the animals for several months after release.
What The Data Showed
None of the three captive-reared crocodiles attempted to return to the breeding facility where they had lived, which was the most encouraging result.
“Instead, they settled into small, well-defined areas and moved in much the same way as the local wild crocodile we tracked, which tells us they are possibly able to adapt to their new environment seamlessly.”
The outcome was very different for Jongra.
“Unfortunately, the results weren’t as good for the wild crocodile Jongra, who was translocated about 132km from his home before being released,” Somaweera said. “Although Jongra didn’t make it back to his original capture site during the study, his movements were very clearly going in that direction. He traveled far more each day than any other crocodile we tracked, covered an exceptionally large area, and even recorded single-day movements of more than 30 kilometers: all typical signs of homing behavior.”
A New Approach To Conservation
Practical use for conservation programs could come from comparing captive-reared crocodiles with those that were moved to a new location as wild animals.
“These findings suggest that releasing subadult and adult captive-reared crocodiles can be a viable strategy to strengthen wild populations,” Somaweera said. “For translocated crocodiles, it’s important there is careful release planning to manage their tendencies to return home.”
| Crocodile Group | Home Behavior After Release |
|---|---|
| Captive-reared females | Settled into new areas, no return attempts |
| Translocated wild crocodile (Jongra) | Moved toward original capture site |
The Study And Its Funders
A piece of research known as “What is home? Post-release movements of captive-reared and translocated mature saltwater crocodiles in Bangladesh,” appeared in the journal Wildlife Research. It was backed by the Deutsche Gesellschaft für Internationale Zusammenarbeit, with IUCN Bangladesh and the Bangladesh Forest Department doing the work under its leadership.
Why This Matters For Reintroduction
For a long while, conservationists have relied on young animals released into the wild as part of reintroduction efforts, though such attempts carry a heavy cost: the odds of these juveniles surviving are very low, and it takes a great deal of time before they can reproduce. A quicker path toward rebuilding a diminished population might instead involve larger, raised-in-captivity crocodiles.
According to the research, letting go of young and grown-up crocodiles raised in captivity appears to offer a practical way to bolster natural populations. However, the animals released still display powerful homing instincts, which means any plans for their release need to take those tendencies into consideration.
The tale of Jongra is one of sorrow, yet his data stands as proof for the scientists. Those raised in captivity changed to fit their surroundings. The wild crocodile who was moved elsewhere attempted to return home. That contrast holds weight for anyone planning a future release.
A clear course of action has been put forth for those working to protect wildlife. Rather than waiting for young creatures to reach adulthood, there is now reason to consider releasing grown, proven survivors instead. The change rests on an observation: certain crocodiles, once set free, show no interest in returning.