Unlike previous mass bouts of illness, such as one involving domoic acid that devastated mostly young pelicans last summer, the current problem involves a significant number of adult birds, like the one found dead Sunday in the backyard of Dru Hammond's home in the foothills near Carmel Valley Village, in Monterey County.
"We've lived in this house 12 years and we've never seen a pelican here before," she said. "My husband found it by our small pond. It looked like it just laid down and died there."
Pending completion of blood and tissue analysis, speculation on possible causes of the event has become a main topic of conversation among animal rehabilitation workers.
Some wondered whether pelicans afflicted by domoic acid in years past had developed a lower tolerance.
Others suggested that the birds had somehow ingested fire retardants and chemical residues washed to sea after recent devastating fires, or caught a virus.
"We've ruled out starvation because there are plenty of fish in coastal waters right now," said Jay Holcomb, executive director of the Northern California-based International Bird Rescue Research Center. "We're seeking answers from all the experts we can find."
Brown pelicans plunged to near zero population growth in the 1960s and '70s because the pesticide DDT infiltrated their food in nesting grounds such as Anacapa Island, about 11 miles off Oxnard. DDT residues in fish the pelicans consumed were believed to have prevented the mothers from depositing calcium in the shells of their eggs, which caused them to break easily.
When DDT was banned in the United States in 1972, the species started to recover. In February, the Interior Department announced a proposal to remove brown pelicans from the national endangered species list.
More than 70,000 breeding pairs of pelicans inhabit California and Baja California, and total numbers have surged to about 620,000 birds along the West Coast, Gulf Coast and Latin and South America.
"They're pretty tough, having survived everything they've been through," said veterinarian Erica Lander of the San Pedro rescue center. "But pelicans are also very fragile, and they need our help."
For more information on helping the birds, visit www.ibrrc.org.
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louis.sahagun@latimes.com
