A phenomenon known as "nocturnal circulation," caused by brightly lit oil platforms in the Gulf of Mexico, is proving deadly for thousands of migratory birds.
Scientists recently have seen evidence of nocturnal circulation's toll off the coast of Alabama. Reports Ben Raines in the Mobile Press-Register:
Feathers of woodland birds found in tiger shark bellies this fall bolster the theory that the Gulf’s offshore oil and gas platforms pose a fatal danger to migrating birds, according to scientists from the Dauphin Island Sea Lab.
“The best way I can describe what we found in the sharks is to think of a hairball like cats cough up,” said Marcus Drymon, a Sea Lab scientist who dissected several of the sharks. “The balls are just solid feathers and about as big around as a grapefruit. We caught these sharks during the fall migration in the general vicinity of the platforms off Alabama.”
The story is an example of journalists and scientists working together to pinpoint an environmental problem. Writes Raines:
Drymon and his fellow scientists said they have found feathers in years past during an ongoing shark survey but didn’t make the connection to migratory birds until they read a November Press-Register article.
It described a 2005 federal study documenting a phenomenon called “nocturnal circulation,” during which birds migrating across the sea on cloudy nights became disoriented by the brightly lit oil platforms. The birds flew around a platform for hours, often until they died of exhaustion and fell into the water.
In some instances, scientists estimated that flocks of 100,000 or more birds were circling a single platform.
The 2005 study called for more investigation, but federal officials never followed up. Scientists at Dauphin Island, however, do not intend to let the issue rest:
Drymon said the scientists planned to publish their findings and seek research money. He said DNA testing on the feathers in the sharks’ stomachs could help identify more species being eaten.
In addition, a relatively new technique that relies on weather radar to track bird migrations could pinpoint platforms where flocks of birds ended up circling.