Once believed extinct, Hong Kong’s giant lizards return to the wild ... after being imported as pets then dumped – via Herp Digest

February, 25, 2016, South China Morning Post

A giant lizard thought to have become extinct in Hong Kong could be re-establishing a small population in country parks, a conservationist says.

Dr Gary Ades, head of the fauna conservation department of Kadoorie Farm and Botanic Garden, said common water monitors captured in country parks were occasionally handed in to the centre. The reptiles have almost certainly been released or escaped from the illegal wildlife trade, he said. However, it was highly likely they were breeding in small numbers.

“This interests us on a conservation level because the monitor is probably one of our native species that went extinct, maybe a hundred years or so ago, and so quite a few conservationists in Hong Kong would like to see it come back,” he said.

“We’re rooting for the few escapees, if they manage to survive our cool winters in Hong Kong, if they’ve got the right genetic makeup, because some … are from Malaysia and more tropical areas, and they probably don’t survive the winter. But there may be a few out there that are doing OK, and they might be the starting stock for a reintroduction of the water monitor.”

Anthony Lau, a PhD candidate at University of Hong Kong who has studied lizards for almost a decade, said the monitors were a popular pet among reptile lovers in the city. They could be bought in pet shops and owners feed them on mice, but would release them once they grew too large.

The common water monitor (Varanus salvator), is the world’s second-largest lizard after the Komodo dragon, Lau said. An adult can grow to 1.5 metres to 2 metres in length, although there is a record of one monitor in Sri Lanka growing as long as 3.21 metres.

Sightings of the common water monitor, also called the Asian water monitor, were first officially recorded in Hong Kong between 1961 and 1963 — in Sha Tau Kok, Fanling, Stonecutters Island and Cha Kwu Ling — according to University of Hong Kong’s School of Biological Sciences. Later sightings, from the 1980s onwards, were most likely escapees or released animals, it says on its website.

Lau said the disappearance of low-elevation wetlands partly explains why the monitor had not been spotted much since the 1960s. Housing development on many wetlands, mostly in northwestern and northeastern parts of New Territories, have “all but destroyed their original habitats”, he said.

The monitor is an indiscriminate carnivore that eats small mammals, fish, frogs, birds and their eggs, but also decaying matter. It is aggressive if aroused, hissing loudly and opening its mouth wide, thrashing its tail if cornered, HKU says. enable JavaScript if it is disabled in your browser.

Both Ades and Lau agreed it would be good to see the lizards reestablished in Hong Kong because they would fill a void in the ecosystem.

“They’re a good cleanup species; they eat a lot of carrion and they basically clean up the forest floor. There isn’t an animal existing in Hong Kong at the moment that’s good at doing that in the same way as the monitor,” Ades said.

Lau said: “If they do indeed persist in the wild, they could refuel the ecological role [of scavengers and predators] once played in the ecosystem. In that sense, it’s a good thing.”

Lau said more monitors had been seen in recent years around the city’s canals and reservoirs, but he knew of no evidence of a breeding population, such as the appearance of juveniles. “If the population is really persistent, you should see different sizes, but all you see are adults,” Lau said.

HKU says the lizard is found from Sri Lanka through to Southeast Asia and in southern China, where it is classified as critically endangered or extinct in the wild.

A spokesman for the Agriculture, Fisheries and Conservation Department said an injured monitor was rescued by the department from a water catchment in Tai Lam Country Park in April 2014. “The animal was sent to the AFCD Animal Management Centre for treatment but died after arrival,” the spokesman said.