Southern California rescues are dealing with an influx of sick and dying brown pelicans and it remains unclear what’s causing the problem.

Calling it a “major crisis,” the International Bird Rescue’s Los Angeles Wildlife Center said it is being inundated with brown pelicans.

More than 101 pelicans were brought into the center for care since May 12, with more expected this week, according to the Bird Rescue.

Many of the birds arrived injured, including some that had been stuck with multiple fish hooks, hit by cars or have fractures for unknown reasons. A few just arrived cold and starving.

Similarly, the Wetlands and Wildlife Care Center in Huntington Beach is also dealing with an influx of sick and injured pelicans.

The rescue noted getting four times as many pelicans as usual, many of them still young.

“They’re being found in very poor body condition, they’re hungry,” Debbie McGuire told KTLA. “There’s also some deceased ones out there on the beach being found.”

It’s not just the beach. The seabirds are showing up in inland areas, elementary school playgrounds, parks and streets.

Many of the birds brought in — around 40% — have died within the first hour or two of arriving, according to the Wetlands and Wildlife Care Center.

McGuire said what’s happening is “very concerning” and no one yet knows what’s causing it.

California Department of Fish and Wildlife spokesman Tim Daly said the agency is aware of an increase in sick and dying brown pelicans in Southern California.

“We are working quickly to receive some carcasses so we can perform necropsies at the department’s Marine Wildlife Veterinary Care and Research Center and the Wildlife Health Laboratory,” Daly said in an email. “Until information on cause of death is available, we are unable to provide a likely cause of the problem.”

The Wetlands and Wildlife Care Center was one of the organizations that participated in an emergency meeting Thursday morning to discuss the flood of injured birds.

“I’m always concerned when there’s an unusual mortality event — especially so widespread,” McGuire said. “I mean, we’re talking the entire coast area of Southern California.”

McGuire said the phenomenon could be the result of a variety of causes, including a disease or an environmental reason tied to red tides or tar balls.

“We have really no idea,” McGuire said.

Meanwhile, the Bird Rescue theorizes that part of the problem may be a lack of available fish stocks.

“We’re seeing a mix of fledglings, second-year birds, and mature adults, which makes me think it could be a food supply issue rather than a simple influx of starving fledglings,” said Dr. Rebecca Duerr, Bird Rescue’s director of research and veterinary science.

The rescue said there were similar inundations of brown pelicans in 2010 and 2012 at Bird Rescue that lasted for months and involved hundreds of pelicans.

Brown pelicans were on the endangered species list in 1970 but were removed from the list in 2009.

Anyone who sees a pelican in distress is asked to stay away and contact a local wildlife center.