"Siamese Crocodile"

Film 3
(one hour special)

January 20th-February 9th 2002

Location of OBA film3:3

(mouse-over for view of Thailand)


Crocodylus siamensis

The Siamese crocodile (Crocodylus siamensis) is probably Asia's most endangered crocodile and could arguably be the most endangered crocodile in the world, rivalled for this unenviable title, probably only by the Cuban crocodile (Crocodylus rhombifer). It exhibits a wide but extremely fragmented distribution in Cambodia, Laos, and Indonesia (Kalimantan). There are historical reports for the species from Burma, Malaysia and Java (Indonesia). The main range of the crocodile is centred either in the Cardomom Mountains and Sre Ambel River region of western Cambodia or from Lake Tonle Sap to northern Cambodia and over into southern Laos. All other populations are miniscule and highly threatened, including the recently re-introduced populations in Cat Tien National Park, Vietnam, and Pang Sida National Park, southeast Thailand. This last population is especially important because the species was long thought to be extinct in Thailand, the country for which the crocodile was originally named, the old name for Thailand being Siam.


Distribution of the Siamese crocodile, Crocodylus siamensis, (blue)
Extant populations: A: s.Laos; B: n.Cambodia (Lake Tonle Sap);
C: sw.Cambodia (Cardomom Mts and Sre Ambel River); D: Indonesia, Kalimantan (Mahakam River);
E: Vietnam (Cat Tien NP - reintroduced); F: Thailand (Pang Sida NP - reintroduced);
: Thailand (Kaeng Krachan NP - expedition location).
Extinct or historical populations believed extinct: Burma, Malaysia (Peninsula) & Indonesia (Java)
Adapted from Simpson & Bezuijen 2010 Siamese Crocodile Crocodylus siamensis pp.120-126
in Crocodiles. Status Survey and Conservation Action Plan (3rd ed) Manolis & Stevenson, IUCN SSC CSP.

Crocodiles have long been hunted for their skins and many population were shot out before wild populations became protected by international treaties such as CITES (Commission for the International Trade in Endangered Species of Flora and Fauna) which set quotas or out-right bans on hunting wild crocodilians. Skin traders then established crocodile ranches and farms, either harvesting and hatching crocodile eggs from the wild or capturing crocodiles, breeding them in captivity, hatching the eggs and raising the young crocodiles for slaughter.Very soon there were more Siamese crocodiles in captivity than in the wild, certainly in Thailand, but a large captive bred stock should be able to supply the demands of the skin trade and ensure the survival of the species - in theory.

The problem was that many crocodile farm owners began hybridizing their Siamese crocodiles with the much larger Saltwater or Estuarine crocodile (Crocodylus porosus). This marine species has fewer osteoderms in its skin and the skin is more sought after than that of some freshwater species. Some farm owners where even hybridizing Siamese crocodiles with Cuban crocodiles, and maybe other species too. This thoughtless hybridization was mixing the gene pools of the captive crocodile populations making it very difficult to determine which crocodile was a pure-bred Siamese crocodile and which a hybrid. There are up to 16 external differences between saltwater and Siamese crocodiles which would enable a crocodile biologist to tell them apart, the most important being the absence of the twin pairs of elevated post-occipital scales from the neck of the saltwater crocodile (see below). These scales are present in all other crocodiles and have led to the saltwater crocodile being given the skin trade name of "naked-neck crocodile". However, since hybrids may exhibit a combination of all or any of these 16 characteristics they cannot be relied upon to define a pure lineage of Siamese crocodile in captivity.

Identifying the Siamese Crocodile
Siamese crocodile,
Crocodylus siamensis
Saltwater crocodile,
Crocodylus porosus

Re-introduction programs to re-establish wild populations of this endangered crocodile are underway in Thailand and Vietnam but the important question is, is the founder stock being introduced into the wild comprised of pure Siamese crocodiles. This question can only really be answered by comparing the DNA of the founder stock with that of pure Siamese crocodiles, but which are the pure Siamese crocodiles?

The question could be answered by sampling a wild population that has never been in contact with farm crocodiles, has not originated from escaped or released farm crocodiles and is too far from the coast or from major tidal rivers or large lakes to be influenced by wild populations of saltwater crocodile. This was the Holy Grail for the Crocodile Management Association of Thailand back in 2002, all they needed was DNA from a wild Siamese crocodile from a guaranteed pure, uncontaminated population, except no such population existed in Thailand, until........... (see below)

Siamese crocodile, Crocodylus siamensis


Map of central Thailand showing primary and secondary expedition locations
(click on map for enlarged view)
Map of southern Thailand showing expedition locations
(click on map for enlarged view)

Facts about Kaeng Krachan National Park
(sources Wikipedia and others)

The Kaeng Krachan National Park is located in southwestern Thailand, near the top of the peninsula and southwest of Bangkok. Almost 2,500 in size, the national park was established in 1981. To the west lie the Tenasserim Mountains which rise to 1200 m and form the border with neighbouring Burma, while to the east is the 46.7 lake created from the Phetchaburi River by the Kaeng Krachan dam, constructed in 1968.

Although an area of outstanding beauty and biological significance, which has been put forward as a potential World Heritage Site, it is also an area with a degree of unrest as Mong fighters seek sanctuary on the Thai side of the border when then Burmese army mounts an offensive against them. This action then brings in the Thai army to drive the fighters back and during these periods the national park becomes a no-go area for visitors.


The Film Crew and Expedition Participants

From the UK:
Roger Finnigan (Director)
Emma Ross (Associate Producer)
Mark O'Shea (Presenter)
Mark Stokes (Camera)
Terry Meadowcroft (Sound recordist)

In Thailand:
Passanana Boontua "Namfon" (location manager & fixer)
Bam Tesrumpun (assistant fixer)
Dr Chukiat Sirivichayakul (expedition doctor)
John "Caveman" Gray (John Gray's Sea Canoes)
Kho (Phetburi River rafters)

Tony Lynam (Wildlife Conservation Society)
Yosapong Temsiripong (Crocodile Management Association)
Somkait Junsawang "Kait" (Yosapong's assistant)
Steve Galster (WildAid Thailand)
Thanit Palasuwan (Chief, Wildlife Protection Division)


The Crew: (l-r )Terry Meadocroft, Roger Finnigan, Mark Stokes &
Mark O'Shea, at Khao Yai
click to enlarge
The Fixers: (l-r) Passanana Boontau "Namfon" & Bam Tesrumpun,
with Reticulated pythons, Python reticulatus,
on the Phetchaburi River


The Contributors: Mark O'Shea with Tony Lynam
on the Phetchaburi River.
click to enlarge
The Contributors: Mark O'Shea with Yosapong Temsiripong with a Reticulated python, Python reticulatus,
on the Phetchaburi River.

The Expedition

The idea for this film arose when this photograph appeared on the internet.

The photograph was taken on the Phetsburi River in the Kaeng Krachan National Park in southwestern Thailand, near the top of the Malay peninsular and near the Burmese border. The area is extremely remote and the sand bank where the photograph was taken is only accessible by boat, rafting down the river.

That the photograph ever existed at all is a miracle. It was taken with a camera trap, a remotely operated camera in a water-proof housing that fires one frame every time the infrared beam is broken. The New York based Wildlife Conservation Society and the Thai Royal Forest Department had set up a series of these camera traps in the Kaeng Krachan National Park in an effort to access tiger populations. Each camera holds a 36 exposure film and periodically the WCS fieldworker would visit and replace the films in the cameras.

A remote camera trap on the Phetburi River

'Our' camera contained an eclectic collection of images, one tiger, a leopard or two, even a passing Buddhist monk, but the majority of the images were of otters and monitor lizards, at least the first 36 frames of the 36 frame film were, but for some reason this film contained a 37th frame and it was the animal captured on that last shot that got everyone at WCS excited, and kick-started our expedition.

Clearly stomping away from the camera towards the water was a crocodile. Two Siamese crocodiles had been captured on this river over 30 years but the population was beleived extinct, like many others across the country of "Siam". This photograph seemed to prove otherwise. It was too far inland and away from the habitat of the saltwater crocodile and too far from human habitations or crocodile farm operations for it to be a released or escaped crocodile. The 37th frame contained an image of what could only be a wild Siamese crocodile, presumably one with pure Siamese crocodile blood and pure Siamese crocodile DNA, the sort of animal that could provide baseline DNA data with which all captive and potential founder stock crocodiles could be compared, if only it could be captured and sampled.

That was to be our task!

Siamese crocodile, Crocodylus siamensis

As well as mounting a major river-borne expedition to find the Phetchaburi crocodile we also set out to discover what is being done to protect endangered wildlife within Thailand and we made a few side-trips of interest, some of which did not make the final film but which are included here.

The primary locations around Thailand visited during filming in 2002 were:

1. Bangkok, Samut Prakan & Chonburi Provinces:
a) Bangkok
b) Crocodile Farms & Temple
c) The Wildlife Raid

2. Satun Province:
a) Tarutao Island

3. Nakhon Ratchasima Province:
a) Khao Yai National Park

4. Phetchaburi Province:
a) Kaeng Krachan National Park
b) Phetburi River - KU camp to Croc camp
c) Phetburi River - Croc camp
d) Phetburi River - Croc camp to Pong Luek

Filming schedule & itinerary:
Sunday 20th January - Depart UK, arrive Bangkok
Monday 21st January - Bangkok
Tuesday 22nd January - Samut Prakan & Chonburi Provs.
Wednesday 23rd January - Bangkok
Thursday 24th January - Hat Yai & Tarutao Island, Satun Prov.
Friday 25th January- Tarutao Island, Satun Prov.
Saturday 26th January - Tarutao Island, Satun Prov.
Sunday 27th January - Tarutao Island, Satun Prov.
Monday 28th January - Bangkok
Tuesday 29th January - Khao Yai, Nakhon Ratchasima Prov.
Wednesday 30th January - Kaeng Krachan, Phetchaburi Prov.
Thursday 31st January - Kaeng Krachan, Phetchaburi Prov.
Friday 1st February - Kaeng Krachan, Phetchaburi Prov.
Saturday 2nd February - Kaeng Krachan, Phetchaburi Prov.
Sunday 3rd February - Kaeng Krachan, Phetchaburi Prov.
Monday 4th February - Kaeng Krachan, Phetchaburi Prov.
Tuesday 5th February - Kaeng Krachan, Phetchaburi Prov.
Wednesday 6th February - Kaeng Krachan, Phetchaburi Prov.
Thursday 7th February - Kaeng Krachan, Phetchaburi Prov.
Friday 8th February - Kaeng Krachan, Phetchaburi Prov.
Saturday 9th February - Bangkok

At the end of each expedition of Season Three the Directors were asked to write a short "director's take" on the project. They were called "Director's Notes". Read the contribution from "Siamese Crocodile" Director Roger Finnigan here.


Expedition Results include a full life-list for the 2002 expedition to Thailand.