The Cozumel Thrasher: One Bird Away From Extinction

WASHINGTON, DC, July 9, 2004 (ENS) - A bird native to the Mexican island of Cozumel has been rediscovered a decade after scientists declared it extinct. A single Cozumel thrasher, Toxostoma guttatum, was sighted last month by a team of field biologists, the American Bird Conservancy and Conservation International said today. The species is no longer considered extinct but now has the distinction of being the most threatened bird in Mexico.

To protect the Cozumel thrasher and other rare species from disturbance, the exact location of the discovery is not being disclosed to the public.

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Drawing of the Cozumel thrasher (Drawing courtesy BirdLife International)
"The rediscovery of the Cozumel thrasher is a reminder of two key things - the importance of tropical islands for biodiversity conservation, and the importance of never giving up on a species - no matter how rare,” said Dr. Russell Mittermeier, president of Conservation International.

The Cozumel thrasher is an endemic bird found only on the island of Cozumel off the Yucatan Peninsula in Mexico. Scientists estimate that as many as 10,000 once thrived on the island, but numbers fell steeply in 1988 after Hurricane Gilbert slammed into the island.

The thrasher became rare, but small numbers were known to exist until it was last sighted in 1995. That same year, Hurricane Roxanne ripped through Cozumel and may have also contributed to the species’ decline.

Previous recent expeditions to find the Cozumel thrasher failed to find any of the birds.

Then last month, a team of field biologists working in conjunction with Villanova University and the Mexican counterpart of the Island Endemics Institute, spotted a single individual, confirming that the species was not yet extinct.

The field biologists were on a rediscovery mission sponsored by American Bird Conservancy and Conservation International.

"This is terrific news for the species," said Dr. George Wallace, vice president for International Programs at American Bird Conservancy. "It opens a door to a range of possibilities that we hope will lead to the establishment of a protected area if more birds are found."

The Cozumel thrasher is a medium-sized bird, 23 centimenters (nine inches) long, similar to a mockingbird.

A long, curved black bill tops a gray face. Its upper parts are a rich chestnut-brown with two white wing-bars, and its white underparts are heavily streaked with black.

Its song is described as a complex scratchy warbling.

Although the hurricanes are believed to have had a major negative impact on the birds, scientists speculate that other factors contributed to the decline, because the Cozumel thrasher likely survived hurricanes for millennia.

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Semi-deciduous forest is the Cozumel thrasher's preferred habitat. (Photo by Robert L. Curry courtesy Villanova University)
Introduced species, especially predatory boa constrictors brought to the island in 1971 and now abundant, may have contributed to the thrasher's demise.

Some positive factors encourage conservationists to hope that the thrasher may come back to Cozumel. Large tracts of deciduous and semi-deciduous forest, thought to be the birds' favorite habitat, still remain, and they are not hunted or trapped for the pet trade.

Formal protection and management of Cozumel’s habitat to foster the thrasher could benefit other species on the island, the conservation groups maintain. They point to two other native bird species, 15 endemic bird subspecies, and at least three endemic and threatened mammal species.

The team will now try to determine the size and range of the population represented by this single bird, and then return next January, when the birds are known to sing more frequently, to attempt further surveys.