Just when it seemed as though the California brown pelican population was flourishing, having rebounded from near-extinction over the past century, the iconic birds have suffered another significant setback.
The University of California at Davis has released findings of a survey that reveal a sharp decline in the number of breeding pairs in Mexico’s Sea of Cortez, also known as the Gulf of California.
About 90% of California brown pelicans breed and raise their chicks in the gulf. Biologists visit sites that typically hold tens of thousands of nesting birds.
But this year many those sites were alarmingly deserted, in some cases totally deserted.
“That’s what we call a failure, a bust. The bottom dropped out,” Dan Anderson, a UC Davis biologist who was part of a survey team that also involved a Mexican ecological group, told ABC News.
California brown pelicans can often be seen soaring up and down the California coast, and their abundance during the past few years seemed to indicate a burgeoning population.
But if a new year class is substantially diminished, as it seems to be, far fewer pelicans might be seen in the next few years.
It’s possible that the crash could be linked to a developing El Niño in the equatorial mid-Pacific.
Water temperatures are warmer than normal in the Sea of Cortez and bait populations have shifted, affecting the pelicans’ ability to find food.
However, there could be more to this problem than a developing El Niño.
"During most El Niño events we've seen, numbers of nesting attempts drop by at least half to two-thirds, and production goes down, too," Anderson said, in a UC Davis statement. "But it drops from thousands to hundreds, not to 10 or less."
California brown pelicans, in recent decades, began a remarkable comeback after nearly being wiped out because of DDT pesticide poisoning.
They were declared an endangered species in 1970, and removed from the list in 2009, when their population was estimated to number 150,000.
The large birds, which feed by plunging into the water and catching fish with their large beaks, are found as far north as Washington.
–Photo: Two California brown pelicans rest atop a rock earlier this month beyond Cabo San Lucas at Land's End. Credit: ©Pete Thomas