Acid, Algae, and the Case of the Disappearing Pelican

brown pelicANEarly in January, brown pelicans began falling out of the air from Baja, California to Southern Oregon. Reports of these large, brown birds crashing into cars and boats, wandering disoriented along beaches, or huddled in backyards alarmed wildlife experts, who had thought the brown pelican was on the verge of return.

The brown pelican earned a spot on the endangered species list in the California/Nevada region in 1970, when their numbers began to plummet as a result of DDT. Banned in the U.S. in 1972, DDT causes the shells of avian eggs to thin and crack, killing the embryos before they can mature.

The brown pelican measures about 4.5 feet from beak to tail at maturity, and weighs 8 to 20 pounds. With a wingspan between 6.5 and 7.5 feet, brown pelicans are the smallest members of the eight pelican species, and can be identified by their brown and white necks, white heads with pale yellow crowns, blackish-brown belly and coal black legs and feet.

Brown pelicans can live up to 40 years and are strong swimmers, but the young are barely able to fly. Virtually unchanged since they first appeared on earth some 40 million years ago, pelicans spend their lives along coasts, rarely more than 20 miles from a shoreline, and as such they are susceptible to all the pollution humans generate. They can go blind from repeated diving into polluted waters to fish, and easily succumb to avian botulism, caused by eating diseased fish found in the warm, shallow waters along the shoreline.

In the past month, ornithologists have recorded about 460 sick or dead brown pelicans. The survivors appear malnourished and disoriented. Some suspect these unfortunates were driven south from the Oregon coast after a severe winter storm brought high winds and disastrous conditions at sea.

dan According to Dan Anderson, an avian ecologist at the University of California, the birds flew 1,000 miles from their roosting site on East Sand Island in the Columbia River (Oregon) to California in an effort to find food and more habitable conditions. The birds got wet, temperatures dipped below freezing, and record-force winds may have confused their internal navigation systems, which often use wind as a directional beacon.

The tale of their flight, according to David Jessup, a senior veterinarian for the California Department of Fish and Game, is shown in their injuries, which include frozen toes and foot webs, and lesions on their pouches. However, even the most confused were not showing evidence of brain damage.

This rules out domoic acid, a neurotoxin in algae which was tied to both the 2006 and 2007 episodes of deaths among pelicans. In fact, according to the International Bird Rescue Research Center, or IBRRC, these domoic acid-induced deaths have been occurring regularly every spring since 2001, when the Center opened its San Pedro location.

Other investigators, who identified domoic acid in the blood samples of four brown pelicans, say the case isn't closed. In addition, five of 14 water-based algae samples taken offshore in the locations where the pelicans are turning up also show low levels of domoic acid. This might be a good causal indicator, except for the fact that domoic acid poisoning usually expresses itself in pelicans that are of average weight and otherwise healthy. Domoic acid has also been implicated in the increase in behavioral abnormalities in California sea lions.

On a related note, researchers are finding alarmingly high levels of urea in the San Francisco Bay area, likely as a result of leaky septic systems and home gardens. These levels, occurring in sampling from the Bay to Monterey, may even be high enough to stimulate toxic algae blooms, since the levels mirror those used in labs to make algae grow. These findings, which appeared in the November issue of the academic journal Harmful Algae, may further link human activities to the explosion of harmful algal blooms and toxins like domoic acid.

Scientists will try to isolate the primary cause of brown pelican deaths because that is what scientists do. The truth is always somewhat more complicated. In the case of the pelicans, climate change and destabilization have lead to bigger storms and warmer and more toxic oceans (especially along coasts), which causes more widespread, lethal algal blooms that poison the fish and mussels on which pelicans feed. Weakened by the latter, pelicans are then ‘done in' by the former.

In the case of climate change, human-created emissions have caused warming, which in this millennium translates into melting glaciers and poles, leading to cooler, salt-free water in some parts of oceans over which earth's major winds pass, delivering colder, wetter weather in some areas while other areas, like Australia (whose climate is tied to the Indian Ocean), suffer continued heat and drought. And this describes only one facet of climate change.

Nothing is ever as simple as it appears. By the time we realize the error of our Western mode of thinking, which attempts to isolate causes rather than identifying patterns, the California brown pelican - and at least 800 other species - will have disappeared in what is now being called the Holocene extinction event.

Related Reading:
A Quarter of All Mammals Now Endangered: 2008 Red List
Saving the Vanishing Vaquita

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  • Posted on Feb. 14, 2009. Listed in:

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