(NaturalSociety) Something is going on in the world of California brown pelicans; migration patterns are off-schedule and breeding is significantly down, but the birds aren’t sharing their secrets with biologists, leaving the scientists to guess about the cause of the disruptions.
“I was just sort of flabbergasted at seeing 3,500 brown pelicans resting in Malibu Lagoon,” said Dan Cooper, a biologist who monitors birds in that region. “I checked my notes, and I have numbers in the hundreds, but I’ve never seen anything like that.”
Cooper noticed the influx of pelicans in April, months in advance of their regular migration. Normally, the larger birds move in after other, smaller birds’ nesting seasons. The early pelicans are affecting the nesting season of these smaller birds as well, as they are forced to compete for space and resources.
“The absolute numbers are not shocking. It’s just the timing. They’re early, and when they’re early like this, that’s when they impact our nesting birds,” said biologist Kathy Molina.
Researchers are puzzled, but the early migration isn’t the only thing troubling them. Dan Anderson of the University of California Davis says he estimates this year’s brown pelicans have “reared less than one percent of the young they normally would.”
“It’s been almost a nearly complete failure to breed, which is quite unusual actually,” said Anderson. “At one island that we study, Isla Salvatierra, which would normally have 8,000-10,000 young, only had like 20 young.”
The researchers have a few ideas about what’s causing the disruption in brown pelican life cycles. One of those is weather.
“This was the first time that a major El Nino event could be directly tied to these massive breeding failures,” stated Kimball Garrett, an ornithology collections manager at the Natural History Museum, according to NaturalNews. “It’s become clear that this can happen in many areas and not just that little narrow area along the equator.”
El Nino is a weather pattern that causes unusually warm ocean water and can disrupt both fish population and thusly, birds. Low populations of anchovies and sardines could be blamed on an El Nino event, and it’s these factors that are being blamed with the nesting failure. But, Anderson says that can’t explain it all.
“Populations do decline somewhat during El Niño years, but not nearly as drastically as what we saw widespread this year. 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. But it drops from thousands to hundreds, not to 10 or less.”
Some have suggested even the nuclear disaster Fukushima has disrupted the supply of fish for the pelicans. Recently, tens of thousands of fish washed up on the California coast – the second time this has happened since 2011. These fish would have otherwise likely fed the hungry pelicans.
Brown pelicans were only removed from the endangered species list within the last five years. Too many seasons like this one and we could be looking at a threatened population again.
“They’re very long lived for birds. They’re going to live to breed for even decades, and a single-season failure is almost meaningless to the population,” Garrett said. As such, for now, scientists are taking the wait-and-see approach.
“Just a couple years of success can really turn things around when you consider that a bird in essence only needs to replace itself in its lifetime for a population to be stable.”