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A venomous cottonmouth snake displays its namesake white mouth as a scientist prepares to capture it on Florida's Seahorse Key in November 2006.

The tiny island on the Gulf Coast is renowned among researchers for its teeming numbers of poisonous snakes.

About 600 vipers slither around the 165-acre (67-hectare) island—in some areas with an average of 22 cottonmouths on every palm tree-covered acre.

"It's almost a [subject of] folklore among natural historians," said biologist Harvey Lillywhite, who has been studying the snakes for nearly six years.

Many scientists have puzzled over how so many snakes can thrive on an island with no fresh water and only a scant number of mammals to prey on.

The secret to the snakes' success, Lillywhite believes, is Seahorse Key's other inhabitants—tens of thousands of birds that nest there from spring to fall.

The snakes aren't eating the birds, the scientist says—instead they live almost exclusively on the huge amounts of dead fish that the birds drop, vomit, and excrete every year.

"There's this disgusting carrion of fish that falls down for the snakes, and the snakes essentially scavenge on it," Lillywhite said.

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