After another El Niņo winter in California, biologists with Point Blue Conservation Science observed abnormally low breeding success for most species of seabirds on the Farallon Islands, and reduced presence of other birds and wildlife out at sea.
A common murre holding an adult anchovy, which is too large for murre chicks to eat. Photo by Ron LeValley
BC STAFF REPORT
Published: September, 2019
After another El Niño winter in California, biologists with Point Blue Conservation Science observed abnormally low breeding success for most species of seabirds on the Farallon Islands, and reduced presence of other birds and wildlife out at sea. Given that climate models forecast more El Niño winters in the future, researchers are alarmed.
In a unique partnership with the U.S. Fish and Wildlife Service, the official managers of the Farallon Islands, Point Blue biologists have been living on the islands continuously for 50 years, studying the wildlife there. Pete Warzybok, current Farallon Islands program manager with Point Blue, has logged more nights on the remote islands than anyone else in modern history.
“We track the differences in wildlife populations and breeding success very closely from year to year. There are always good years and bad years,” Warzybok said. “But this year we saw extremely low breeding success or near failure for most of the seabirds.”
Cassin’s auklets usually succeed in about 75 percent of their breeding attempts; this year biologists observed a success rate of less than 10 percent. In another example, researchers typically find around 150 pelagic cormorant nests on the island; this year only one nest was found with eggs, and it was subsequently abandoned.
Similar results were observed for other seabird species including rhinoceros auklets, common murres and pigeon guillemots.
Meanwhile, at-sea observations echoed the findings on the Farallones. In partnership with NOAA’s National Marine Sanctuaries, Point Blue conducts three annual research cruises, observing ocean conditions and wildlife from Central to Northern California. Dr. Jaime Jahncke, director of Point Blue’s California Current group, has been participating in these cruises since 2004.
“This year, we found a very low number of seabirds in the Gulf of the Farallones off the coast of Northern California,” said Dr. Jahncke. “While these trips are usually filled with bird and whale sightings, we observed just a handful of Cassin’s auklets, very few common murre chicks and no blue whales.”
In general, El Niño winters in California bring warmer land and water temperatures, more rain throughout the winter, more extreme precipitation events and reduced upwelling—the process through which cold, deep nutrient-rich water rises to the ocean’s surface. Often, El Niño winters also bring late storms, particularly the warm southern storm known as a Pineapple Express. This year was no exception, with all of the above traits playing out throughout the season.
And it appears that 2019’s El Niño was weaker than average overall, but displayed concentrated impacts on California, a phenomenon known as a “California El Niño.”
It makes sense that El Niño conditions would affect breeding. “So much of the richness in ocean life we have in the waters off of California can be attributed to the upwelling effect,” Dr. Jahncke said. “The cold, nutrient-rich water is very productive for plankton and krill, two key types of organism on which the rest of the ocean food web depends.”
Less upwelling means less plankton and krill, which means fewer young-of-the-year rockfish and anchovies—all of which are food for seabirds. In an absence of juvenile anchovies and rockfish, Warzybok observed adult murres and rhinoceros auklets bringing back larger adult anchovies to their chicks. These adult anchovies are often too big for the chicks to eat, resulting in many chicks starving to death.
“As scientists, we try our best to be detached observers of ecological processes,” said Warzybok. “That said, as conservationists, we want to see a thriving ecosystem and it’s heartbreaking to watch seabird chicks starve due to a lack of suitable food.”
“We recognize that these are complex ecosystems and we don’t fully understand how all the pieces connect,” said Warzybok. “Nonetheless, variability in the system over the past few years is far different than we saw in the first 40 years of our data. Climate models are predicting more El Niño winters and more unpredictability, which means more threats to seabirds. To me, this drives home the need to reduce other threats to seabirds and other wildlife. We need to do everything we can to protect special places like the Farallones because they provide marine life with the time and space they need to adapt, leading to a more resilient ecosystem.”
