Greater Xe Champhone Wetland Complex, Lao PDR,  April 4, 2024 – A new research paper in the Journal of Threatened Taxa has confirmed for the first time the nesting of a reintroduced female Siamese crocodile. Two hatchlings resulted from the nesting, and they are now being head-started, raised by conservationists in captivity until they are old enough to be successfully released into the wild. 

The paper can be found here.

Steven G. Platt, a herpetologist with the Wildlife Conservation Society and lead author of the paper said: “This is something of a landmark in our conservation efforts, and as far as I know, the only time nesting by a head-started and reintroduced female Siamese crocodile has been confirmed, indicating these are effective conservation strategies. We also unequivocally established that head-started female Siamese crocodiles are capable of reproducing when nine-years-old.

“Since 2013, this project has released more than 180 head-started crocodiles. About 115 crocodiles are now being head-started; and not part of that number, 37 others were released in March 2024.”

The Siamese crocodile is considered one of the most imperiled and poorly-studied crocodilians in the world. Reintroductions—often in conjunction with head-starting of juveniles—are a critical component of efforts to restore viable wild populations of this species and other reptiles, especially turtles and tortoises.

Siamese crocodiles are large (up to 4 meters or 13 feet) mound-nesting crocodilian that occur or formerly occurred in freshwater habitats of mainland Southeast Asia (Thailand, Laos, Vietnam, Cambodia) and the Sundaic Islands of Java and Borneo. Populations throughout this geographic range are now greatly diminished as a result of habitat destruction, commercial hunting for skins, direct persecution because of perceived danger to humans and livestock, and illegal collection to stock crocodile farms.

The observations of the crocodile documented in the research paper were obtained from camera traps in the in Savannakhet Province where there are natural and anthropogenic wetlands, agricultural ecosystems, scrubland, and forest.

The authors note: “While collecting eggs for incubation in May 2022, we were able to identify a unique series of notched tail scutes on a female C. siamensis as she aggressively defended a nest.

“From these markings we determined the female was hatched on 11 August 2012 (age = 9.75 years) and released in March 2014. A camera-trap placed at the nest on 11 May 2022 and recovered on 5 July 2022 recorded 1724 images.

“These images indicated the female remained in attendance at the nest throughout the monitoring period. Camera-trap imagery captured eight nest repair events and two nest defense events; during the later the female defended the nest from village dogs.”

The program has reduced mortality among the young crocodiles from 90-95% to less than 5%, thereby boosting population recovery trajectories.

WCS Lao PDR, in close collaboration with the local communities and Government of Lao PDR, developed a long-term crocodile plan aiming to restore a viable population of this species.

Funders include: the European Union (EU); Agence Française de Développement (AFD); Critical Ecosystem Partnership Fund (CEPF); and Margaret A. Cargill Philanthropies (MACP)