Smithsonian Tropical Research Institute scientists, led by William Laurance, said sea turtle nesting attempts are impeded by lost or abandoned logs floated downriver from forests to coastal lumberyards in the Gabonese Republic. Some logs float out to sea and wash ashore, forming large tangles.

Laurance's team, in co-ordination with J. Michael Fay of the Wildlife Conservation Society, counted more than 11,000 logs along Gabon's beaches.

"It's really sad to see what the logs are doing to the turtles," Laurance said. "Sea turtles move very slowly on land. When a log blocks their path, sometimes they just give up and return to the sea. In other cases they lay their eggs too close to the waterline, where the eggs are killed by seawater."

The researchers estimated up to 14 percent of all turtle nesting attempts are thwarted by logs. Most turtles nesting in the area are leatherback turtles (Dermochelys coriacea), a critically endangered species, Laurance said.

The study is to be published this month in the online edition of the journal Oryx.