Scores of weak and disoriented California brown pelicans have been slamming into cars and boats, landing on highways and airport runways, and turning up dead in back yards and parking lots many miles from their normal coastal habitats.
This behavior is far from ordinary, say wildlife experts. A lapel-grabbing press release from the International Bird Rescue Research Center in San Pedro says that something has gone seriously awry with the birds.
Typically this time of year we would see a significant die-off of YOUNG brown pelicans. We are seeing a larger than normal die-off of ADULTS - those are tremendously valuable to a population, potentially contributing to other species. This is not a good sign.
Secondly, we are seeing some common conditions - disorientation - birds landing inland, being found in neighborhoods, on roads, runways, etc. This disorientation implies something is wrong, possibly neurologically - they are not JUST STARVING!
Scientists are baffled by the mysterious illness, which has affected pelicans along the California coast from San Francisco to San Diego and whose symptoms include disorientation, extreme fatigue, and bruises inside the bird's pouches.
One suspect is domoic acid. Produced by algae, researchers believe this neurotoxin can build up in dangerous concentrations in the fish and shellfish that the pelicans eat. Scientists now think that domoic acid was responsible for the bizarre avian mass suicide that occurred on Aug. 18, 1961, in Capitola, Calif., where residents awoke to hundreds of shearwater carcasses in the streets and the sounds of others slamming into their homes. (Capitola was not far from the home of director Alfred Hitchcock.)
But domoic acid poisoning, which has reportedly disoriented pelicans in the past, usually occurs in the spring or summer, not in January. And according to the San Jose Mercury News, testing of coastal waters has not revealed an increase in domoic acid concentrations. What's more, according to the Associated Press, birds poisoned with domoic acid typically experience seizures, which have been not observed in the current population of sick pelicans.
Decimated by DDT in mid-20th century, the California brown pelican – the smallest of the family of water birds with distinctive pouched beaks– was listed as an endangered species in 1970. The pesticide was restricted in the US two years later, and the species began to recover. In February 2008, the Department of the Interior proposed removing it from the list.
The species has proved to be resilient, but bird rescuers are still worried. The LA Times quotes a volunteer with the International Bird Rescue Research Center:
"Pelicans have been hammered over the years by oil spills, DDT, domoic acid, fishing line, gunshots, starvation and parasites -- we're expert at dealing with those problems," said David Weeshoff, a volunteer at the San Pedro center. "But right now, we're scratching our heads over the cause of this event. Not a good deal."