The Science of Monsters

Daphne Du Maurier, author of the well-known gothic novel Rebecca (1938), asked this very question in her novella The Birds published in her story collection The Apple Tree (1952). In The Birds, a small town in Cornwall, England is suddenly attacked by seabirds. The attacks are brutal with no answer as to why. Unlike Arachnophobia in which the catalyst of the film is an Amazonian spider coming to the United States, and in Cujo in which a dog is bitten by a rabid bat, the bloodthirsty birds of The Birds have no specific trigger or reason for their brutality. Perhaps it is this randomness that creates a whole new layer of horror to the trope of deadly animals.

Alfred Hitchcock seemed to think so. In 1940 he had adapted Du Maurier’s Rebecca into a successful picture starring Laurence Olivier and Joan Fontaine, so it was no wonder he dove back into Du Maurier’s source material, choosing to base another one of his suspenseful films on her novella. Before hiring screenwriter Evan Hunter to adapt and tweak the plot of The Birds, Hitchcock did his own research on a real-life bird “attack” in California. In 1961, a few mere weeks after this incident, the director requested news copy from the Santa Cruz Sentinel to study.

He read of the eerie morning of August 18th, 1961, when residents of Capitola, California, a smaller community on the coast of Monterey Bay, awoke to a frightening discovery. Droves of sooty shearwaters, a medium sized seabird native to the area, were acting erratically. Some crashed into rooftops, windows, and cars. Others flopped, dying in the streets, while more vomited their fish dinners into the grass. It was a short incident, but one that terrified and traumatized those who had witnessed this mass bird hysteria. Desperate to find an answer for this sudden behavior change of the seabirds, scientists hypothesized that domoic acid poisoning could be to blame. This was never proven, but it is a viable suggestion. Domoic acid is a neurotoxin produced by algae. These algae can then accumulate in shellfish, sardines, and anchovies. When animals or humans ingest this toxin, which was ingested by the shellfish, their brain is affected, causing seizures and even death. “Domoic acid is a tricarboxylic amino acid that is classified as an excitatory amino acid (along with the dicarboxylic amino acids glutamic acid and aspartic acid). It acts through the inotropic non-NMDA receptor and especially affects the hippocampus and amygdala of the brain. The time from ingestion to intoxication can range from minutes to hours.”² Seabirds would undoubtedly be susceptible to this type of poisoning, and the description of the event in August of 1961 mirrors the listed animal symptoms of domoic acid poisoning: head weaving, seizures, bulging eyes, mucus from the mouth, disorientation, and death. In 1991, domoic acid was the official cause of death for hundreds of brown pelicans and cormorants in Monterey Bay, on the same beaches the peculiar bird activity had played out exactly thirty years earlier. A bird attack in 2006 was also attributed to domoic acid poisoning when a brown pelican burst through the windshield of a moving car on the Pacific Coast Highway.

Domoic acid structural formula.

Unfortunately, humans have also been victim to this poisoning. The most dramatic case occurred in 1987. Over one hundred people in Eastern Canada fell ill after ingesting mussels fished from the coast of Prince Edward Island. They described a number of symptoms including nausea, vomiting, severe headache, and most alarming, loss of memory. This amnesia, for some, was permanent. At the time, the doctors called this phenomenon “amnesic shellfish poisoning.” Three of the sufferers died from this painful syndrome caused by domoic acid. In 1991, two months after the bird deaths in California, two dozen people were struck ill with amnesic shellfish poisoning, or domoic acid poisoning, in Washington State. They had all consumed razor clams seized from the coasts of Oregon and Washington. When testing was done after the incident, it was also found that Dungeness crabs in the area were rife with domoic acid. Though human incidents of amnesic shellfish poisoning are rare, according to the Channel Islands Marine and Wildlife Institute, animal incidents seem to be on the rise.

It is generally accepted that the incidence of problems associated with toxic algae is increasing. Possible reasons to explain this increase include natural mechanisms of species dispersal (currents and tides) to a host of human-related phenomena such as nutrient enrichment (agricultural runoff), climate shifts or transport of algae species via ship ballast water.³