just when you thought it might not be that bad
Louisiana’s state bird, the brown pelican, under assault from spreading oil, biologists say
By Bob Marshall, The Times-Picayune
June 01, 2010, 5:48PM
State and federal wildlife agencies spent four decades rebuilding Louisiana’s pelican population after it was decimated by the insecticide DDT. This brown pelican was photographed Sunday in the marsh near Pass a Loutre.
From a distance the small grass and mangrove islands on the eastern side of Barataria Bay seem like the happiest places on the planet for a brown pelican. More than 1,500 of Louisiana’s gregarious state birds are noisily consumed with bringing their next generation into the wetlands. Parents sit on tall nests of sticks and grass that cradle fist-sized eggs, or constantly wing between the bay and the island bringing meals to newly-hatched chicks – tiny, featherless, bony creatures that look more like dinosaurs than birds.
But a slim line separates domestic joy from tragedy. It’s the brown line of oil sludge gripping the islands at the tidal waterline, a chemical cocktail that could at least injure and probably kill any birds that wade through it.
This year it could be a line that decimates an entire generation of Louisiana pelicans, biologists say.
“Young pelicans love to go down to that zone when they first start to walk, because they like getting out of the nest and moving around,” said Mike Carloss, biologist with the Louisiana Department of Wildlife and Fisheries. “But if they get in there with a fresh wave of oil, the result could be devastating.”
Louisiana has about 20 brown pelican nesting sites. This one on the eastern side of Barataria Bay was photographed May 23. Pelicans build nests of grass that rise more than a foot above the ground, but the eggs appear to be picking up oil from incubating parents that swim through oil while foraging in the bay.
That concern has state and federal wildlife officials closely monitoring Louisiana’s 20-odd brown pelican nesting sites, colonies that evoke both pride and fear at the agencies.
The pride comes from the success of a four-decade effort to rebuild the state’s brown pelican population after it had been eradicated by the insecticide DDT. Washed into the habitat from farm fields, DDT saturated the pelicans’ food chain, ultimately causing egg shells to become so fragile they collapsed during incubation.
“By 1963 there were no pelicans left here, so after DDT was banned, we began bringing birds in from Florida to restart colonies,” Carloss said. “We started in 1966, and by 1971 we had reproducing colonies. In 2008, we produced about 375,000 pelicans from the sites. And last year they were removed from the endangered list.”
The fear comes from knowing the recent success still doesn’t guarantee the brown pelican a secure place in Louisiana. The coastal marshes and barrier islands that are its primary nesting and habitat continue to crumble into open water at rates as high as 35 square miles per year.
As prime nesting areas are lost, pelicans are forced to marginal sites such as those small, grass and mangrove islands on the eastern side of Barataria Bay, Carloss said. Moves to protect and enhance those remaining were under way when the Deepwater Horizon rig blew up.
That pushed coastal erosion to the back burner, because oil arriving during the peak of nesting season quickly became a potential disaster.
Carloss estimates the state’s 10,000 breeding pairs, which typically mate for life, are in various stages of nesting, from tending weeks-old offspring to putting finishing touches on nests which rise three to five feet from the ground. Females typically lay two to three eggs, which usually take 23 to 30 days to hatch under constant incubation.
Chicks are born without feathers, but quickly develop down. They are fed regurgitated fish from their parents sack-like bills, and within 62 to 75 days are fledged.
But the BP oil poses an unprecedented lethal threat to the this next generation of pelicans from egg to fledgling, and beyond, biologists said, because waves of poison will be washing toward these nesting sites for months to come.
Egg shells are porous to allow embryos to exchange carbon dioxide for oxygen through the shell, so if enough pores are blocked by oil, suffocation could result. These eggs were photographed May 23 in Barataria Bay.
The worries start with the oil smudges already seen on many eggs, carried there by parents after swimming in the oiled waters of Barataria Bay.
Egg shells are porous to allow embryos to exchange carbon dioxide for oxygen through the shell, so if enough pores are blocked, suffocation could result. Another concern is that the oil’s toxic components – called volatile organic compounds, or VOCs – could pass through the shell, bringing certain death to the embryo inside.
“It all depends on the composition of those smudges,” Carloss said. “If it’s been heavily weathered and most of the VOCs are dissipated, then that wouldn’t be a concern.
“We’d like to know, but going out there to inspect eggs could do more harm than good, because the nests could be abandoned. So we just have to wait.”
After hatching, chicks face skin and internal injury from oil passed to them by their parents’ feathers and the food being supplied, biologists said. The heavy oil residue picked up by parents foraging in the bay can cause lesions on the skin of featherless chicks. And like adult birds, oil residue can be ingested by chicks trying to clean contaminated feathers. Remnants of VOCs can quickly injure internal organs, including kidneys and liver.
Any of these things can happen to chicks and young birds while still on the nests, but they would be almost unavoidable when the young birds begin wading in the circle of oil sludge around their nesting islands.
“A lot will depend on how fresh that oil is,” Carloss said. “If it’s been heavily weathered for weeks, then there probably won’t be many of the VOCs left. That’s good news.
“But there are other components of the sludge that can still do real damage to an adult pelican, much less these young birds.”
Biologists anchored at the islands use binoculars to watch the nests, scanning for signs of impacts. They have already seen one set of chicks that have golden-toned down, and adults that have been partially and severely coated with oil.
“We’re guessing that’s from oil carried to the nests by the adults,” Carloss said. “But we have no way of knowing. We really can’t go stomping around those nesting sites collecting eggs and birds.”
Oil’s lethal threat to pelicans isn’t confined to the nesting sites. Biologists said as long as oil is flowing into the bays, pelicans are at risk from contamination through the food chain. Smaller creatures such as menhaden, sardines, mullet and shrimp that either ingest the toxins or are coated with them, can pass these toxins to pelicans causing illness or death.
“If a mullet or menhaden were to ingest some of the VOCs, they could die, or they could still have them in their bodies when they are eaten by larger predators, like pelicans,” said Kerry St. Pe, executive director of the Barataria-Terrebonne National Estuary Program, and formerly head of Louisiana’s oil spill response efforts. “The VOCs don’t bio-accumulate in the fat or tissue of animals, like some other pollutants. But as long as that oil is out there, and coming ashore, it’s a threat to everything in that ecosystem because it can kill, and it can be passed along and kill other species.”
Spill responders are maintaining a database on the number of birds and other wildlife injured and killed by the spill. Through the end of May the number of all birds killed was less than 200, but wildlife officials who have worked other spills say any accurate count is difficult because many stricken animals are never recovered.
Carloss said many of the dead birds have been pelicans. Oiled pelicans and other birds that are rescued are rehabbed and released on the east coast of Florida, away from the oil, he said.
While the loss of adult pelicans is saddening, biologists are more worried about what the next few weeks will bring. That’s when the pelican class of 2010 – perhaps as many as 100,000 chicks – begins coming of age and moving toward those brown lines.
pictures by George Riedel AP