- This month, conservationists released 10 captive-bred Siamese crocodiles into Cambodia’s Virachey National Park as part of a regionwide effort to boost wild populations of the critically endangered crocodilian.
- The release marked the first such attempt in Virachey. Since the species was rediscovered in Cambodia in 2000, nearly 200 crocodiles have been released in Cambodia’s Cardamom mountains region.
- Efforts to restore or boost Siamese crocodile populations are underway in protected areas in Laos and Thailand, too.
In a conservation milestone, 10 Siamese crocodiles were released this month into Cambodia’s Virachey National Park for the first time, as part of a decades-long effort to save the critically endangered species.
The Siamese crocodile is one of the world’s rarest crocodilians, with less than 1,000 individuals estimated to be surviving in the wild.
The species hasn’t been sighted for more than 20 years in Virachey, one of Cambodia’s most remote national parks nestled in the northeastern corner of the kingdom on the border of Laos and Vietnam.
Combined with recent record-breaking hatchings both in the wild and in captivity, as well as new records of releases into the Cardamom Mountains, conservationists hope to build a second species stronghold in Cambodia.
“It is not every day in conservation that you can say you are achieving and seeing tangible results. This is one of those rare occasions,” said Pablo Sinovas, country director for the NGO Fauna & Flora in Cambodia, in an interview with Mongabay. “We are cautiously optimistic, but at the same time the species is still critically endangered and key wetland habitats across the region continue to decline.”
Similar efforts to save the species are taking place in nations neighboring Cambodia, reducing the risk of extinction and inching towards the goal of downlisting the Siamese crocodile from its “critically endangered” status.
Frank Rheindt, an associate professor in the National University of Singapore’s department of biological science, told Mongabay in an interview that reintroductions across its range “is key to the long-term global survival of the Siamese crocodile.”
“If Cambodia was the only player and you had one or two population clusters around the country, that is pretty good to start with. But ideally, you would want to have a large matrix of populations throughout the former range,” said Rheindt, who has studied the species genomics of Siamese crocodiles. “This only becomes more and more relevant in the next few decades with anthropogenic climate change.”
‘A double novelty’
Siamese crocodiles were thought to be extinct in Cambodia until a Fauna & Flora survey of the Cardamom Mountains rediscovered a small population in 2000. This kicked off the Cambodian Crocodile Conservation Project, which spans both captive-breeding and wild releases.
In the 25 years since the discovery, Fauna & Flora has released 196 Siamese crocodiles into sanctuaries scattered throughout the Cardamoms. The recent event in Virachey pushes the conservation group’s total to 206 released crocodiles. In 2022 and 2023, social enterprise Rising Phoenix released an additional 41 crocodiles in Siem Pang Wildlife Sanctuary in Cambodia’s northeast.
Spanning more than 3,300 square kilometers (1,274 square miles), Virachey is nearly five times the size of the capital city, Phnom Penh.
“The reintroduction of a locally extinct species into a new area, plus our use of new acoustic telemetry technology made this kind of a double novelty release,” said Sinovas.
Sinovas explained that the historical presence of Siamese crocodiles within the national park will likely boost the chances of its survival.
All 10 released juvenile crocodiles were implanted with acoustic telemetry transmitters, which emit soundwaves that are detected by receivers placed in points near the release site. At the end of the year, conservationists will return to collect data from the receivers, which will dictate if future releases in Virachey are viable.
“Assuming that we see the crocodiles have been moving around, which is an indication that they are alive and well, then that will be very useful to then plan additional releases into the area,” said Sinovas, who continued that, as top predators, crocodiles are essential to maintaining ecological balance.
According to Sinovas, plans are already underway to release around 40 juvenile crocodiles in the Cardamoms in April.
Many of these released crocodiles were bred in captivity at the Siamese crocodile breeding center in Phnom Tamao Wildlife Rescue Centre, which recorded its largest ever hatching of 180 crocodiles last year — more than doubling the hatching numbers of any single year since the breeding program began in 2009.
With nesting season rapidly approaching in April, all eyes are on the mating pairs in Phnom Tamao.
“We are fairly confident we will have a good hatching year. I wouldn’t be surprised if we had more than last year because we are continuously improving what we do in Phnom Tamao,” Sinovas said.
The new captive-bred hatching record last year came hand-in-hand with the discovery of 60 wild crocodile hatchlings within a crocodile sanctuary in the Cardamoms. While wild hatchlings have been recorded in the past, mostly in and around the Cardamoms, there had previously never been a record of one with more than 10 crocodiles.
“It is very tough to attribute population gains in the wild to particular release events directly, but there is certainly a lot of circumstances for that in this case,” said Rheindt. “From the magnitude, since it is an unprecedented increase in numbers, it must have been due at least to a great part to the releases.”
‘Matrix of populations’
Siamese crocodiles have been classified as “critically endangered” on the International Union for Conservation of Nature’s Red List of Threatened Species for nearly 30 years. The IUCN describes the species as “among the most threatened crocodilians.”
Historically, habitat degradation and the skin trade pushed Southeast Asia’s Siamese crocodiles to the brink of extinction. But as the demand for Cambodian crocodile skin has shrunk, conservationists are focusing on habitat loss.
“Crocodiles rely on wetlands, which are one of the more threatened ecosystems globally and are shrinking across the globe,” Sinovas said. “One of the biggest challenges for crocodile conservation is maintaining the habitats and it is one of the biggest risks in terms of the potential extinction.”
According to Sinovas, “in that context, it does make sense to identify additional areas where this species can have a foothold. This reduces the overall risk of extinction.”
Similar crocodile conservation efforts are occurring in Cambodia’s neighboring nations.
“We prioritize Siamese crocodile conservation work because we love crocodiles,” said Yosapong Temsiripong, chairman of the Thai Crocodile Farmer Association.
The association donates pure-bred Siamese crocodiles to Thailand’s Department of National Parks, Wildlife and Plant Conservation for release in government-managed protected areas that have existing remnant populations of the species.
At the end of March, the association is donating 15 crocodiles that will be released in Khao Ang Rue Nai Wildlife Sanctuary in eastern Thailand, the western extremity of the Cardamom Mountains.
“Hopefully, in the future, in my lifetime, we will see an abundance of Siamese crocodiles in the wild,” Temsiripong said. “It is important [that] governments, conservationists and farmers work together to recover the Siamese crocodiles, so that in our range states no one is left behind.”
Steven Platt, the Southeast Asia regional herpetologist at Wildlife Conservation Society (WCS), told Mongabay in an interview about the “inkblot strategy” that focuses on establishing a population and then protecting the habitat until the species spreads out.
“The larger a population is, the more resilient it is to extinction,” Platt said. “The populations are small and fragmented at the moment. Ideally, we want to join up these sites eventually, but the first step is always just getting them established.”
Platt has spent more than a decade working on Siamese crocodile conservation in Laos. To date, WCS has released 170 crocodiles into the Xe Champhone Wetlands within Savannakhet province in southern Laos. Currently, WCS is head-starting nearly 275 crocodiles in Laos, more than 80 of which are expected to be released in May.
“I hesitate at this point to call the Siamese crocodile a conservation ‘success story’ because habitat loss certainly remains a serious concern,” Platt said. “But the trajectory is moving in the right direction, and I am hopeful.”
Banner image: A recently released juvenile Siamese crocodile in Cambodia, by Anton L. Delgado.
Siamese crocodile hatchlings a ‘promising sign’ in Cambodia, but greater protection needed
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