Some parks have ducks, some have swans. Bangkok's Lumpini Park has hundreds of monitor lizards, which can grow up to two metres (6.5 feet) long. The park's population of the prehistoric-looking reptiles has grown to around 400, leading officials to come up with a plan to relocate them.

Monitor lizards lumpini park Bangkok
A park worker holds a monitor lizard in Lumpini Park in Bangkok Athit Perawongmetha/Reuters

Park staff were dispatched with ropes and snares to hunt down and catch around 40 of the creatures. Luring them out of the water with dead catfish as bait was a difficult task, as they're afraid of humans.

"When some of them are just standing still on land, it's not a struggle to catch them, I just hook them on. But if they are in the water, we have to lure them on to land, which is the difficult part because they are frightened," park official Saifon Netwong told Reuters.

The water monitor lizards are famous throughout Bangkok. Residents and tourists often come across them crawling across roads or alleys or emerging from one of the city's many canals. They can often be found sunbathing on the pavements or slithering out of the lakes in Lumpini Park, an inner-city oasis popular with joggers. Although the lizards don't attack people, they are a threat to the park's fish, plants and landscape, according to Suwanna Jungrungrueng, director of Bangkok's environment department. Their sheer numbers have also caused concern, with reports of cyclists falling while swerving to try to avoid the lizards.

However, Tuanjai Noochdamrong, director of the department's Wildlife Conservation Office, told Reuters that the lizards are vital to the park. "Water monitor lizards clean up all the mess when various animals die and their bodies starts decaying. They also eat rats. Therefore, the lizards clean up all these biowastes and get rid of diseases."

City authorities said the lizards will be transferred to a wildlife breeding centre in Ratchaburi, around 129 kilometres (80 miles) south of Bangkok, where they will be well looked after.