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While brown pelican population is strong, does die-off along California coast point to bigger issue?

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By DINO GRANDONI/The Washington Post

They started showing up in odd places far from the ocean: in the middle of roads, backyards, even a major league baseball game. The wayward marine birds were cold, disoriented, anemic. The stomach of one that veterinary surgeon Rebecca Duerr opened up was full of feathers and wood chips.

Up and down the coast, something was wrong with California’s brown pelicans, but no one was sure what. By the time they got to wildlife rehab centers such as International Bird Rescue, where Duerr works, many of the birds were “essentially on death’s door,” she said.
Nearly 900 brown pelicans were brought into wildlife rehabilitation centers from Southern California to the San Francisco Bay Area this past spring and summer, according to Duerr, with hundreds more dead in the wild. It’s an eyebrow-raising die-off — one of several in recent years — of a bird species that only in 2009 has recovered enough for the federal government to take it off the Endangered Species Act list.
Dead brown pelicans washed up on Molera Beach in Big Sur, Calif., during a time when a large number of pelicans are turning up sick, malnourished or dead along the California coastline.

Now biologists are racing to figure out what is going on with the state’s brown pelicans — and see if the die-offs are a sign of some broader problem lurking in the water off California’s coast.

Their first suspect was avian influenza. The virus has struck more than 170 dairy herds in the United States while raging through wild bird and marine mammal populations around the world. Whether or not it was bird flu was “a very critical thing to determine early on,” said Kelly Beffa, wildlife center manager for International Bird Rescue’s Bay Area center.
But testing showed no signs of the virus. Next, scientists looked for signs of poisoning from domoic acid, a naturally occurring toxin produced by algae. There was no evidence of that, either.
The condition of the pelicans brought in was the biggest clue.

“The birds were extremely skinny,” said Laird Henkel, a scientist at a California Department of Fish and Wildlife veterinary lab. “So starvation was the obvious cause of death.”

But why the pelicans couldn’t find food in the ocean was still a mystery. There appeared to be plenty of anchovies there for them to eat.

One leading theory has to do with the way brown pelicans feed. Flying as high as 60 feet above the ocean, the pelicans plunge headfirst into the water to scoop up fish near the surface with their massive bills and swallow them whole.

But the birds can only divebomb so deep. Storms may have reduced their ability to see into the water, or the fish that pelicans like to eat may be swimming deeper than usual, possibly the result of warmer waters due to climate change, though Duerr and others cautioned that more research is needed on that question.

“It’s not really clear-cut enough to just say, ‘Oh, blame climate change.’ But having warm surface waters in areas that normally are cold ocean is certainly a complicating factor for the animals that live there,” Duerr said. “And we may see more of that in the future.” She is working with the state on a report on the die-off for the U.S. Fish and Wildlife Service.

Until they figure that out, veterinarians are just trying to save as many pelicans as they can.

During the height of the crisis, Beffa regularly pulled 12-hour days. Duerr came back early from knee surgery to pitch in. So far, International Bird Rescue has rehabilitated and released more than 240 pelicans as of early August, with about 40 more still in care.

There had been lingering worries that the federal government acted too hastily when it declared in 2009 that the brown pelican had recovered, said Bergeron. Recognized as being on the verge of extinction in the 1970s, the brown pelican surged back after environmentalists succeeded in halting the use of pesticides that were killing it and other bird species.

“These die-off events are not good news for those individual pelicans,” he added, “but the pelican population seems to still be doing well.”

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  1. azire says

    And there may not be enough food for the additional brown pelicans because of changes in the climate caused by warming. I wouldn’t say it was a good sign of environmental health when a bird’s native environment can’t support an moderate increase in population. I wonder if the population of brown pelicans –prior to widespread pesticide use– can be estimated? If so, it would provide a baseline population level.