LOS ANGELES — Wildlife experts are trying to figure out why sick, disoriented and bruised California brown pelicans are being found in record numbers along more than 1,000 miles of coastline.

The birds, some of them dead, have been spotted from San Francisco to Baja California, Mexico. Many have been found far from their homes on roads, fields and backyards.

The pelicans started appearing late last month north of San Pedro in Southern California, then began appearing farther north, said Jay Holcomb, executive director of the International Bird Rescue Research Center in Fairfield, in Northern California.

The center’s San Pedro facility received more than 40 birds in the past seven to 10 days, while the Fairfield one has received about 25, Holcomb said Tuesday.

A man vacationing in Baja California alerted the center about a similar problem there this week after discovering sick pelicans on the beach south of San Felipe.

“There are dead or sick brown’s all over the place,” Rick Meyer wrote in an e-mail Monday to the research center. “Normally there are just a couple, but in the last 10 days there is one every 100 feet... Something’s going on.”

In the Los Angeles area in the last week, birds have been reported staggering across a road in the beach community of Playa del Rey and on a runway at Los Angeles International Airport. One bird was reported to have struck a vehicle.

Bird rescuers knew something strange was happening because the increasing numbers of sick pelicans involved adults, ages 3 and older, Holcomb said. Typically, this time of year there is a significant die-off of young brown pelicans, but marine biologists say they are seeing a larger-than-normal die-off of adults.

The sick birds are thin, seem confused and disoriented, and have discoloration on their pouches and feet, Holcomb said.

“This type of disorientation in adult pelicans is something we’d see during a domoic acid outbreak, but we have yet to see them exhibiting the other common symptoms,” he said.

Domoic acid, a neurotoxin, is produced by microscopic algae. Birds and sea mammals ingest the acid by eating fish and shellfish that consume the algae.

Birds poisoned by domoic acid generally experience seizures, but the pelicans admitted to the rescue centers did not suffer seizures, Holcomb said.

Rescuers have sent pelican blood samples and carcasses to state and federal wildlife authorities and laboratories that specialize in detecting potentially fatal algae toxins.

Holcomb said test results are expected in about a week.

Meanwhile, veterinarians and volunteers are nursing the growing number of feathered patients with intravenous fluids, medications and a diet of smelt and squid. Holcomb said rescuers have been successful in nursing many of the ailing birds back to health, but the cost is staggering — $500 to $1,000 per bird.

The California brown pelican is a subspecies of the common brown pelican. Its habitat stretches from Mexico’s Sinaloa and Nayarit coasts to the Channel Islands off Southern California.

Brown pelicans nearly became extinct in the 1960s and 1970s because the pesticide DDT infiltrated their food. The species started to recover in 1972 when DDT was banned in the United States.