Anacondas, giant otters and the world's largest bird of prey proved to be worth more than their weight in gold when dredging for the metal was banned in their forest home, conservationists said yesterday.

The ban on gold dredging in the unspoilt region of Guyana follows a campaign by Amerindian villagers, backed by scientists from the Zoological Society of London.

PhD students Rob Pickles and Niall McCann travelled to the Rewa Head in the South American country to study giant otters and tapirs.

The pair conducted an extensive assessment of the wildlife in the area and are working with conservationists in a bid to win international support for Guyana's plan to turn its forests into the world's largest carbon sink.

The Guyanan government wants financial incentives to keep its forests standing to prevent the release of greenhouse gases.

Conservationists believe the country could be a test case for implementing the "Redd+" initiative which, under an international climate change agreement, would see poor countries paid by rich nations to protect their forests and the carbon locked up in them.

Mr McCann warned that without funding to keep the wildlife-rich forest standing, it could be at risk from industry.

"The Rewa Head currently lies in a logging concession. Unless Guyana is given alternative financial incentives, its government will be forced to lease its land to oil drillers, miners and loggers.

"One of the world's last Edens is on the brink of destruction."

Mr McCann and Mr Pickles recorded 251 bird species and 33 large mammals, including the largest species of snakes, spider, eagle, armadillo and anteater, during their survey.

Mr Pickles said they had encounters with wildlife that biologists could wait years for in the field.