A new photo of an apparently mature Siamese croc captured in the deep jungle of Kaeng Krachan National Park. Credit: DNP/ KKNP/ WCS Thailand

New evidence raises hopes for the survival of rare Siamese crocs in Kaeng Krachan National Park

The recent discovery of evidence of an apparently mature male croc has given a gleam of hope for the more fruitful reproduction and chances of survival of the critically endangered species, Siamese Crocodile (Crocodylus siamensis), in this park

It takes them more than sixteen years to have obtained new evidence to confirm the existence of a rare creature in one prime habitat deep in the country’s lush and largest national park of Kaeng Krachan after some few last sightings in 2004.

And if proved to be true, this could also help confirm the existence of the creature of different sex, after a female beast has been spotted in the area nearby alone for years.

The discovery, led by a joint survey team of the DNP and WCS Thailand, has raised a gleam of hope for this so-called “zombie” species, once dubbed by wildlife conservation scientists years ago, for the fact that it is a species of a population in the park, which composed of “a few and often long-lived individuals, or the living dead that would ultimately be doomed to extinction because of the continued lack of reproductive success”.

And it’s also for the fact that a Siamese crocodile is already placed under the global conservation list as the world’s critically endangered species, and rarely found in the country’s natural settings nowadays.

Credit: DNP/ KKNP/ WCS Thailand

The team, led by Wildlife Conservation Society (WCS) Thailand’s Project Manager of the Wildlife Conservation Project in Kaeng Krachan Landscape, Manoon Pliosungnoen, has been conducting a new field survey since December last year, when they went to the so-called site, Sub Chumhed, the riverside wetland by the Petchaburi River deep in Kaeng Krachan National Park in Petchaburi Province.

The team had deployed two camera traps there in mid-December in a hope that they would help capture photos of the species along with other rare species like the Smooth-coated Otter.

They went back to the site around mid-January and on Jan 20, they got a big surprise as they checked one camera trap and learned that it had recorded an apparently mature crocodile.

Around 400 meters away from the camera trap, the team also found two crocodile scats on the riverbank. They were later measured to be about 4.7 cm and 5.5 cm.

Having calculated the scats based on a scientific formula to get a glimpse of the size of that crocodile, they learned that the creature could be sized around 4.04 to 4.15 meters.

According Mr. Manoon, who has written an initial report on the findings, the existence of a crocodile at Sub Chumhed has long been documented, but there were very few direct sightings, as noted in some studies in 2004.

“From this survey, we have got important evidence suggesting that at least one full-sized individual still occupies Sub Chumhed,” noted Mr. Manoon in his report.

Sub Chumhed is roughly 20 km further upstream from another widely known crocodile inhabiting site, Wang Kha. There, a female crocodile of which the size is estimated to be around 2.4 meters is regularly found roaming the area since the last survey by the DNP-WCS team around ten years ago, 2010-2011. 

Mr. Manoon said the team are not sure whether she has grown up and moved upstream, but the large size on the record plus the absence of the nesting activities upstream have convinced them that she may rather have found her opposite sex.

Mr. Manoon said the team have forwarded their findings to the experts to help scientifically identify the creature’s sex and other features, and are waiting for the results.

“Though we believe that the individual that occupies Sub Chumhed Area is a mature male, regarding its large size and the absence of nesting activity since our survey began in 2010. This could only be precisely confirmed by animal handling or closely investigation or monitoring,” noted Mr. Manoon, remarking that knowing the animal’s sex is crucially important to rescue the remaining population of the species from extinction.

A new photo of an apparently mature Siamese croc captured in the deep jungle of Kaeng Krachan National Park.
Credit: DNP/ KKNP/ WCS Thailand

C. siamensis

According to established knowledge by scientists who have studied Siamese Crocodile in Thailand since the 2000s, they have noted their research and findings in their papers over the past years that the species, Siamese Crocodile (Crocodylus siamensis), is considered one of the least studied and most endangered crocodilians in the world. (In recent years, it’s been listed as a critically endangered species on the IUCN Red List and the Appendix I of CITES, the Convention on International Trade in Endangered Species of Fauna and Flora).

Once being widespread and abundant throughout much of Southeast Asia, the animal’s populations have steeply declined during the past 50 years, largely as a result of widespread habitat destruction, over-collecting to stock crocodile farms, and illegal hunting for skins and meat, the scientists noted.

The remnant populations, which were reported around 10 years ago, were in parts of Cambodia and Lao PDR, with questions over their long-term viability lingering. Little was known in Malaysia and Indonesia either.

In Thailand, the species was abundant in wetlands of central and southern Thailand, but the population declines were noted in the early 1900s due to widespread hunting. And by 1970s, the only population known to remain in Thailand was of about 200 crocodiles near Bung Boraphet, which was later decimated by illegal hunting for crocodile farm supplies, destruction of nests and eggs, and accidental drowning in fishing nets, the scientists noted.

It was not until the 1990s that there were more reports of crocodiles spotted in the wild, from Pang Sida National Park to Khao Ang Ru Nai Wildlife Sanctuary in the East, with some carcasses found in Yod Dom, while tracks and drag marks were discovered in Phu Khieo Wildlife Sanctuary in the Northeast, and in Kaeng Krachan National Park in the West.

A new photo of an apparently mature Siamese croc captured in the deep jungle of Kaeng Krachan National Park.
Credit: DNP/ KKNP/ WCS Thailand

Around 2001, the photos of the first adult crocodile in Kaeng Krachan was captured by a remote camera in one survey, while tracks and drag marks were also found along the Petchaburi River. The photographic evidence from the same river was presented again in 2004. 

Since, more surveys and studies in the park have been attempted, including those in the 2010s.

According to the paper, A Survey to Determine the Conservation Status of Siamese Crocodiles in Kaeng Krachan National Park, published in the Herpetological Conservation and Biology in late 2012, the joint DNP-WCS study team had conducted an intensive survey and study through upstream of the Petchaburi River and its tributary, Mae Pradone.

Crocodile signs were detected, including tracks and scats, although nocturnal sightings revealed none of them. Based on scientific calculations and assessments, the team said they would be of large juvenile or subadult crocodiles.

Villagers’ recalls in in-depth interviews to accompany the report also showed the presence of adult and small crocodiles, which were exploited and hunted to serve crocodile farms, especially during the 1980s.

The more critical components out of the survey trip were the crocodile nests representing their reproduction, although they were proved later by the evidence left at the discovered sites as being non-productive. For instance, the clutch sizes showed over 30 to 50 egg inside, but none either produced embryos or survived predators.

One of the nests found during the trips made by the team in 2010.
Credit: DNP/ KKNP/ WCS Thailand

According to that survey and study, the team estimated that at least four to six crocodiles were roaming around the upper reaches of the Petchaburi River, but since, there have been assumptions on only one same female beast, which has been present and spotted around Wang Kha. The latest sighting of her was in July last year. 

“Assessing long-term trends in this population is difficult, but we found nothing to indicate the number of crocodiles has increased since their presence was first documented in the park (the early 2000s)

“Whether the upper Petchburi River ever supported high densities of Siamese crocs is open to question. There is no mention of crocodiles in historic faunal surveys of the region now encompassed by KKNP, suggesting they were never common,” the team wrote in their report, citing that the nature of rough and fast-flowing streams and landscapes would contribute to the hindrance of the reproduction of the species there.

The team noted that the apparently small number of breeding adults and their continued failure to reproduce, coupled with the extinction risks inherent in any small population, called into question the long-term viability of this population. 

Without direct, aggressive conservation intervention by park authorities, the eventual extinction of Siamese crocodiles within the park was inevitable, the team remarked. 

“The crocodiles in Kaeng Krachan are both of both national and global conservation significance; not only is this population (the only extant wild population known in Thailand), it is also one of just a handful of such populations remaining within the historic range of C. siamensis,” the team had noted.

As of today, the creature is one of the four critically endangered species found in the park, proposed for the world’s protection of the Natural World Heritage Site along with other critical species including tigers and other natural values of the park.

A video clip of an apparently mature Siamese croc captured in the deep jungle of Kaeng Krachan National Park.
Credit: DNP/ KKNP/ WCS Thailand