If you’ve spent any time along the coastline in San Diego County, you’ve probably seen California brown pelicans gliding silently in formation, perching on a pier railing, or perhaps, after tucking in those enormous wings, plunge feeding for a meal of fish. They really are magnificent birds to behold, an impressive symbol of everything that is coastal California. Today, the brown pelican population is fairing well, despite a serious reduction in past years attributed to DDT use; agricultural runoff of the pesticide resulted in its high concentration within the food chain. Fish tainted by DDT were consumed by the pelicans, which lead to an accumulation of the toxin within their bodies. As a result of the contamination, female browns began laying thin-shelled eggs that were cracked under the weight of an incubating adult bird. Finally, after a banning of DDT in the early 1970s, the population began to recover, and has continued to steadily grow.

With the ban of DDT, and subsequent increase in California brown pelican numbers, both bird watchers and environmentalists could breath a collective sigh of relief. However, these sea birds must still contend with a number of challenges within their range. At SeaWorld San Diego, avian specialists and veterinarians may be called upon to disentangle a wing wrapped with monofilament line, suture a torn pouch, or remove an ingested fish hook-the result of dining on fisherman’s bait. First aid, however, is not limited to pelicans in coastal San Diego.

The Salton Sea in the Coachella Valley has become an important stop over for migratory waterfowl, including brown pelicans, within the Pacific Flyway. In recent years, some brown pelicans from the Salton Sea have been diagnosed with avian botulism, a disease state that usually leads to a flaccid paralysis of the musculature and possible death. The causative organism, a bacterium called Clostridium botulinum, is present in the fish that brown pelicans eat. Clostridium itself doesn’t cause the paralysis, but rather a potent toxin liberated by the bacteria affects neuromuscular transmission. Interestingly, of the five fish species present in the Salton Sea, only tilapia is responsible for botulism toxicity in the pelicans; dead or dying tilapia provide an ideal environment for the proliferation of Clostridium and production of botulinum toxin.

Each year, ailing pelicans from the Salton Sea, some completely limp and near death, are transported to SeaWorld for advanced care. In an effort to save these birds, an established treatment protocol, developed at Seaworld, is put into action. Birds are weighed, given a complete physical, and classified into four categories according to the severity of infection; Stage 1 pelicans are the most critical, incapable of even holding up their heads, while Stage 4 pelicans are described as “non-critical” and require far less intervention to recover. Depending on the their condition, birds may be fed a pelican gruel or solid fish, given fluid replacement therapy, and administered antibiotics to combat the infections. Some birds are also given an antitoxin to block the effect of the toxin produced by C. botulinum. Following the rehabilitative effort, pelicans that are capable of flying and strong swimming, eating on their own, maintaining good weight, and free of antibiotics are classified as Stage 5 birds, and are prepared for release.

Given the importance of the Salton Sea to migratory waterfowl, it is likely that SeaWorld personnel will continue to rescue and rehabilitate brown pelicans on an annual basis. The collaborative effort of aviculturists, veterinarians, and lab technicians gives these birds a “second lease on life”, and helps to preserve an important part of the California heritage.

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