By Guy De Launey
BBC News, Phnom Penh
The Siamese crocodiles were declared extinct in the wild in 1992
The Siamese crocodile is one of the world's rarest creatures.
Judging by its week-day morning performance at the Phnom Tamao wildlife sanctuary, it might also be one of the grumpiest.
Attempts to lasso the beast around the snout have contributed to its ill-humour. The croc only wants to come out of the enclosure on its own terms.
A joint team from conservation organisation Fauna and Flora International (FFI) and Cambodia's Forestry Administration is wrestling around a dozen crocodiles a day at Phnom Tamao - all in the name of preserving the species.
The Siamese was declared extinct in the wild in 1992, and while several population sites have been found in recent years, numbers are still critically low.
Conservationists are hoping to replenish the numbers with a captive breeding programme, but first they have to identify animals which suit that purpose.
Conservationists hope to replenish numbers by breeding them in captivity
The crocodile they have their eye on is making a disconcerting, low-pitched growl; it is in attack mode.
"Get your foot out of there," yells Adam Starr, FFI's crocodile programme manager. A flip flop-shod member of the team, armed with only a bamboo pole, beats a hasty retreat.
The Siamese might not be anything like as large as other crocodile species - for example the fearsome saltwater - but it can still inflict considerable damage on a human unwise enough to provoke it while limbs are within snapping range.
A "death roll" could easily break an arm or leg clamped between the crocodile's teeth.
Eventually the lasso is firmly tightened around the animal's upper jaw.
That is the cue for team members to grab the croc by the tail, wrestle it out of the enclosure and place it into a shallow pit.
More ropes and a blindfold keep the beast subdued so the conservationists can do their work.
"You can't tranquilise them," Mr Starr explains. "Their instinctive reaction to distress would be to dive into the water. When the tranquiliser kicked in, they'd drown."
As many as half a dozen people pin down the croc while the vets go to work, taking blood and tissue samples for DNA analysis and injecting a tracking chip into the tail.
They will do the same for each of the crocodiles at the sanctuary - around 70 in all.
The conservationists are hoping to find pure-bred Siamese among the population at Phnom Tamao.
The samples will be analysed at a laboratory in Thailand, and confirmed Siamese crocs will be paired off for breeding.
No quick fix
The director of the wildlife sanctuary, Nhek Ratanapich, admits he feels a great responsibility for making sure the programme is a success.
"We have found that there are less than 250 Siamese crocodiles in the wild, and they are isolated so there is a lot of in-breeding," he says.
Siamese crocodiles can inflict considerable damage on a human
"This project may allow us to breed the Siamese species and reintroduce it into the wild."
Humans are the Siamese crocodile's only predator; the animals are prized for their soft leather.
In Cambodia, however, their habitats are in protected areas, and the local human population now largely treat their reptilian neighbours with respect.
That means conservationists are optimistic about the chances of survival for any offspring from the breeding programme.
"Previously in Cambodia, with its civil war and social strife, there were not very effective laws to protect these animals," says FFI's Adam Starr.
"Today the Forestry Administration and other government ministries have been very good at developing these laws.
Confirmed Siamese crocs will be paired off for breeding
"There are rangers in protected forest areas, so we believe there's a better chance right now to breed crocodiles - and have them looked after properly."
There will be no quick fix. Siamese crocodiles mature slowly, so it may be 15 years before conservationists will be able to tell whether or not the project has been a success.
For now they are simply hoping that what they are doing will be enough to ensure the species is never declared extinct again.