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When thousands of frenzied seabirds invaded the coastline
near Monterey, Calif., in the summer of 1961, the scene played out like
a Hollywood horror movie. The Santa Cruz Sentinel reported a “rain” of birds known as Sooty Shearwaters slamming into homes and other shoreline structures.
“Dead and stunned seabirds littered the streets and roads in the foggy early dawn,” the newspaper reported on August 18, 1961.
Two years later, a similar plotline made it onto the
big screen through the eyes of filmmaker Alfred Hitchcock—in the Macabre
form of The Birds. The master of suspense and mystery, responsible for
Psycho, Rear Window and other classics, happened to be visiting the area
during the bird invasion. The event fueled inspiration for the film
(along with a chilling avian story published in 1952 by British author
Daphne du Maurier).
And now scientists have produced fresh evidence of what caused the birds to go crazy.
A team that includes Mark Ohman of Scripps Institution
of Oceanography at UC San Diego recently reported in Nature Geoscience
that high quantities of Pseudo-nitzschia, a type of phytoplankton,
produced a neuro- toxin that likely moved up the food chain and was
eventually gobbled up by the birds.
The researchers say the neurotoxin—known as domoic
acid—poisons the brain and “causes symptoms such as confusion,
disorientation, scratching, seizures, coma and even death.”
The key behind the new findings was the ability to
travel back in time to study ocean samples from a half-century prior.
The California Cooperative Oceanic Fisheries Investigations (CalCOFI),
one of the world’s longest continuous marine monitoring programs,
provided the necessary samples now stored in the Scripps Pelagic
Invertebrate Collection, a library of archived marine samples. Such
resources allowed Ohman and his colleagues to study the gut contents of
several specimens of grazing zooplankton that were captured off Monterey
prior to the bird frenzy.
It is an example, says Ohman, of how detailed and
carefully preserved geo-referenced materials can provide answers to
questions that were never anticipated when they were being collected.
—Mario C. Aguilera, ’89
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