We have seen them go for chicks of all sorts of birds, from ducks to moorhens, coots and geese

Wildlife officer Dave Humphrys

Now wardens have warned parents to think twice before buying their children exotic pets for Christmas.

It is understood the red-eared terrapins were abandoned several years ago, as the craze for the children's cartoon, which was also known as "Teenage Mutant Ninja Turtles", died down.

However, they have since grown from the size of a 50p to that of the average dinner plate.

Dave Humphrys, a wildlife liaison officer, warned: "People get these animals but don't realise how big they get and how difficult they can be to handle, so they have to get rid of them.

"If wildlife centres can't find a home for them then they let them into the wild, without thinking of the consequences."

The dumped terrapins have colonised the lake

Mr Humphrys explained the terrapins have now colonised around the ornamental lake.

"We have seen them go for chicks of all sorts of birds, from ducks to moorhens, coots and geese," he added.

Park staff have so far managed to capture three of the terrapins and transferred them to wildlife sanctuaries.

However, many more are thought to remain in the ponds.

Populations of young birds in the park have dropped recently as a result of the terrapin menace, said Camden council employee Mr Humphrys.

Importation ban

He said: "The birds have a number of predators including foxes, domestic cats, crows and seagulls, but it only takes a small addition to upset the balance."

A spokeswoman for the Department for Environment, Food and Rural Affairs said an offender found guilty of dumping terrapins could be jailed for two years.

They are classified as a non-native species under the Countryside and Rights of Way Act 2000, and cannot be let out into the wild.

The importation of terrapins into the UK for anything other than scientific purposes was banned in 1997.