At less than 12 inches long red eared terrapins or sliders hardly look like the stuff that ecological nightmares are made from. Unfortunately, the same animal that makes a quiet domestic pet, is carving a trail of destruction across Bermuda's wetlands. In fact, a better name for this terrapin might be 'terror-pin'.

Mark Outerbridge, marine biologist with the Bermuda Biodiversity Project, battles the red eared terrapin menace on a daily basis.

"Somerset Long Bay has a large population," said Mr. Outerbridge. "I pulled about 250 from Pittman's pond and there are still some in the pond. There was a time last summer when you could stand by the pond on a sunny day and count nothing but terrapin heads."

Red eared terrapins are native to the southern United States but were introduced to Bermuda as pets. Some people got bored with their red eared terrapins and released them into Bermuda's protected wildlife areas or onto golf courses, while other terrapins simply escaped captivity and became feral.

Females with eggs frequently make a dash for it, and bury their eggs in the wild. They can lay anywhere from two to 22 eggs, and can live up to 20 years.

Those babies hatch and quickly take over whatever ponds are at hand. At the moment they are one of the few living things that can survive in the heavily polluted Mills Creek drainage ditch.

"They were a big obstacle for the restoration of Pittman's pond," said Mr. Outerbridge. "Herons eat them when they are little, but when they are grown nothing can touch them."

Once the terrapins are in a nature reserve there is little that can be done to get rid of them, except attempt to manage the population.

Environmentalists fear that the terrapins might destroy a species of killifish that may exist in Warwick Pond and nowhere else in the world.

"I have pulled out almost a hundred from Warwick Pond," said Mr. Outerbridge. "The killifish is on the decline. One of the reasons for this could be that the red eared terrapins are eating them. When I looked at the diet of some of the red ears from Warwick Pond, they were eating the fish, and I also found bird bones in their stomachs."

The killifish are not only important to Bermuda's ecology, they are also an excellent mosquito control, so when they are eaten by the terrapins, it makes it easier for mosquitoes to breed.

"You get the terrapin population out or down, and there is a bit more of a chance for the killifish to make a comeback," said Mr. Outerbridge.

Scientists from Dr. Jamie Bacon's Amphibian Project are interested in examining red eared terrapins taken from the water because they can reveal vital clues about the toxicity of the pond environment.

"We want to look at the terrapins who have been living in the ponds for decades to see what sort of metals are in their systems," said Mr. Outerbridge. "We want to know if it is as bad for the terrapins as the toads. That is one thing we are looking at. We are looking for funding for this project. A project like that could cost in the thousands depending on how detailed you want to go."

Mr. Outerbridge said there has been some suggestion that there are pollutants in Pittman's pond that predate its days as a bottle dump.

"There would be some sewage from the cows that were kept nearby for a long time, but while it would make swimming in the pond unpleasant, but there are other worse nasties to consider," he said.

While there are lots of broken bottles still around the pond, glass doesn't leach out chemicals in the same way that something like a battery would.

"Ponds are a natural sump," said Mr. Outerbridge. "Everything that is bad runs into the ponds.There may be a link between pollutants in the pond and air quality."