The birds circle the rig lights at night until they drop from exhaustion. No new government studies are planned until 2013.
Sunday, January 01, 2012, 6:00 AM
DAUPHIN ISLAND, Alabama -- Heaped on a table at the laboratory, the pile of beaks, feet, eyeballs, feathers and whole bird carcasses testified to what may be the oil industry’s most unexpected environmental impact.
For the second year in a row, researchers at the Dauphin Island Sea Lab have found the remnants of migratory birds in the bellies of tiger sharks caught off Alabama.
The body parts provide compelling evidence of the mortal toll that oil platforms take on birds migrating across the Gulf of Mexico each year. The carcasses also highlight an issue federal officials have essentially ignored since it was revealed seven years ago.
A federal study from 2005 described a phenomenon known as “nocturnal circulation.” Groups of birds migrating across the Gulf on cloudy nights can be disoriented by the brightly lit oil platforms and fly around them in circles for hours, often until they become exhausted and fall into the sea and die.
That study called for further investigation, but federal officials never followed up, according to a statement from the Bureau of Ocean Energy Management, Regulation and Enforcement emailed to the Press-Register.
...
Some observers have described clouds of up to 100,000 birds circling a single platform at night.
But calculating the actual toll has been difficult, as the carcasses simply disappear when the birds fall.
Complicating an accurate count of the dead, many birds are believed to stop circling and resume their migration when the morning sun comes up. Whether they are able to complete their journeys after flying in a circle for eight hours remains an open question, scientists say.
Enter Marcus Drymon, a shark researcher at the Dauphin Island Sea Lab. After reading an article about the phenomenon in the Press-Register in 2010, Drymon began paying more attention to the masses of feathers he often found inside sharks he was dissecting.
In the past two years, Drymon’s team has identified the remains of a number of woodland birds inside the sharks, including brown thrashers, woodpeckers, scarlet tanagers, meadowlarks, catbirds, kingbirds and swallows. With the addition of DNA analysis, Drymon hopes to gain a fuller picture of what is getting eaten and how often.
…
With numerous platforms off the Alabama coastline, Drymon said there was no question the sharks often feed near the giant structures. And, he said, the platforms are directly in the center of the Dauphin Island Trans-migration thruway, one of the most important migration corridors in the hemisphere.
…
Drymon said that a few days after he read about the nocturnal circulation problem last year, he noticed feathers in the throat of a tiger shark he was pulling onto a research boat.
“This is a really interesting aspect of this story. Look at the migration pathway. These are not birds we would expect to find in tiger sharks,” said Drymon, whose research represents the first proof that Gulf sharks are routinely gobbling up land-based birds.
…
Stanley Senner, with the Ocean Conservancy, said Drymon’s work also has important ramifications for the scientists calculating how many birds died during the BP oil spill.
“I will be eager to see how the U.S. Fish and Wildlife Service accounts for birds consumed by sharks in the final tally of birds killed by BP oil,” Senner said.
The 330-page federal study found that once migrating birds “get inside the cone of light surrounding the platform, they are either reluctant to leave or have a difficult time getting out, seemingly becoming trapped by the surrounding wall of darkness.”
When the Bureau of Ocean Energy Management, Regulation and Enforcement — then known as the Minerals Management Service —published the study, it also issued a press release titled “Oil and Gas Platforms Provide Haven for Migrating Birds.” The press release made no mention of the circling behavior, although it was listed in the full study as one of three “primary” impacts that platforms have on migratory birds. Birds flying into the platform structures and dying was another primary impact.
A paper published by researchers in the North Sea suggested that a switch from yellow lighting at platforms to green lighting would nearly eliminate the circling behavior. Scientists working with Royal Dutch Shell speculated that such a switch would reduce the number of birds circling platforms in the North Sea from 6 million a year to 600,000.
...U.S. officials have not followed up on the North Sea work.
