Although the brown pelican population is strong, does the mass die-off along the California coast indicate a larger problem? • YachatsNews.com
Currently, biologists are trying to figure out what’s going on with the state’s brown pelicans – and whether the species’ decline is a sign of a larger problem lurking in the waters off California’s coast.
But tests showed no signs of the virus. Next, the scientists looked for signs of poisoning by domoic acid, a naturally occurring toxin produced by algae. There was no evidence of that either.
The condition of the introduced pelicans was the biggest clue.
“The birds were extremely emaciated,” said Laird Henkel, a scientist at a veterinary laboratory at the California Department of Fish and Wildlife. “So starvation was the obvious cause of death.”
Why the pelicans did not find food in the sea remained a mystery. It seemed as if there were enough anchovies there for them to eat.
One of the leading theories has to do with the way brown pelicans feed. They fly up to 20 metres above the sea and dive headfirst into the water, using their huge beaks to scoop up fish near the surface and swallow them whole.
But the birds can only reach so deep. Storms may have limited their ability to see into the water, or the fish that pelicans like to eat may be swimming deeper than usual, possibly due to warmer waters due to climate change. But Duerr and others cautioned that more research is needed on this question.
“It’s not clear enough to just say, ‘Oh, climate change is to blame.’ But warm surface water in areas that are normally cold ocean is certainly an aggravating 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 species extinctions for the U.S. Fish and Wildlife Service.
Until they figure that out, veterinarians are simply trying to save as many pelicans as possible.
At the height of the crisis, Beffa regularly worked 12-hour days. Duerr returned early after knee surgery to help out. By the beginning of August, International Bird Rescue had already rehabilitated and released over 240 pelicans; about 40 more are still in care.
There have been ongoing concerns that the federal government acted too hastily when it declared in 2009 that the brown pelican had recovered, Bergeron said. In the 1970s, the brown pelican was known to be on the brink of extinction, but after conservationists managed to stop the use of pesticides that were killing it and other bird species, it recovered.
“This extinction is not good news for individual pelicans,” he added, “but the pelican population still seems to be doing well.”
