Brown Pelican

Pelecanus occidentalis

Description

The brown pelican is a large, diving water bird, weighing up to 8 lbs (3.6 kg) and having a wingspan of up to 7 ft (2.1 m). It has a light brown body with a white head and neck, which are often tinged with yellow. In breeding season, the back of the neck turns dark brown and a yellow patch appears at the base of the foreneck.

The United States is home to two subspecies of the brown pelican: the California brown pelican (Pelecanus occidentalis californicus ), native to the Southern California Coast; and the eastern brown pelican (P. o. carolinensis ), which occurs on the Atlantic and Gulf coasts. While generally similar in appearance, the California subspecies is slightly larger and shows a darker hindneck and bright red throat pouch during breeding. This red throat pouch is rare among eastern brown pelicans. The brown pelican is one of two pelican species found in North America. The white pelican (P. erythrorhynchos ) winters along the Southern California Coast, the Gulf Coast, and the Atlantic Coast of Florida.

Behavior

Brown pelicans are rarely found away from salt-water and do not normally venture more than about 20 mi (32.2 km) out to sea. They feed almost entirely on fish captured by plunge diving. Brown pelicans are colonial nesters that use small, inaccessible coastal islands as breeding sites. Nesting occurs primarily in early spring and summer. The normal clutch size is three eggs; both sexes participate in incubation. Young are born naked and helpless and acquire down after about 10 days. Fledging takes place at 12 weeks. In some years, depending on water temperature and prey availability, birds disperse northward from their breeding range in late summer. Brown pelicans are only very rarely observed inland. Many brown pelicans stay close to their nesting sites throughout the winter. A portion of the eastern subspecies migrates to Florida, the Caribbean coasts of Columbia and Venezuela, and the Greater Antilles. During cold winters, some Texas brown pelicans winter along the Gulf Coast of Mexico. Brown pelican populations fluctuate considerably from year to year and from place to place. Colonies may switch breeding sites yearly, especially in Florida where the breeding population is widely distributed. Therefore, abandonment of rookeries in one area is no indication of an overall declining population. The pelican is a long-lived species that has evolved with this "boom and bust" reproduction strategy.

Habitat

The brown pelican almost always nests on coastal islands, rarely more than 6 ft (1.8 m) above high tide. In the eastern United States it uses low, sandy islands and spits or mangrove trees for nesting. Islands and spits are subject to erosion and flooding by storm and spring tides, forcing brown pelicans to constantly shift nesting sites. Florida brown pelicans nest slightly above the high tide line on islands of black, red, or white mangroves, and to a lesser extent in other trees and shrubs, including Australian pine, red cedar, live oak, redbay, and sea-grape.

Distribution

The eastern brown pelican has nested along the Atlantic and Gulf coasts of the United States (from the Carolinas to Texas), the West Indies, and Central and South America. Large numbers were once found on small coastal islands in Texas, Louisiana, Florida, and South Carolina, while smaller numbers nested in North Carolina and possibly Georgia. Nesting has not been recorded in Mississippi or states north of North Carolina.

In 1983 several pairs of pelicans nested on a spoil island in Alabama's Mobile Bay, the first nesting recorded in that state. In the early 1800s John J. Audubon estimated up to 9,000 nesting pairs in Florida; 3,000-6,000 pairs in South Carolina; and perhaps a hundred pairs in North Carolina. A small colony of a few hundred birds was seen sporadically in Georgia. Historically, up to 50,000 birds nested in Louisiana and Texas. Between 1957 and 1961, pelican populations in both states declined precipitously because of pesticide poisoning. Nesting ceased on the Louisiana Coast and was very nearly eliminated on the Texas Coast. On the West Coast, the California brown pelican nests on offshore islands in extreme Southern California and Baja California, Mexico. Population estimates before 1968, when regular surveys were begun, indicate that up to 2,000 pairs nested on Anacapa Island and an equal number nested on the Channel Islands. Smaller colonies have been recorded on Santa Barbara Island, San Miguel Island, and Santa Cruz. During the 1930s another large colony, estimated at 2,500 pairs, nested on Los Coronados, near the U.S.-Mexican border. Islands in the Gulf of California have always held the largest population of California brown pelicans. Since the late 1980s the Florida population of brown pelicans has remained stable. In 1989 about 11,500 pairs nested throughout the state in 37 active colonies, stretching from Daytona Beach on the Atlantic Coast to Panama City on the Gulf of Mexico. In South Carolina two colonies support about 5,000 nesting pairs, a population at or above historic levels. The North Carolina brown pelican population has shown an increase in recent years. There are now about five active colonies in two separate coastal areas. Biologists attribute the increase to the northward expansion of the South Carolina population, aided by the recent creation of dredge spoil islands, which provide additional nesting habitat. Along the Texas and Louisiana coasts, the pesticide disaster of the 1950s and 1960s has been somewhat mitigated. The Texas population recovered from a low of less than 100 pelicans in the late 1960s to about 500 pairs in 1989. In Louisiana, where the breeding population was extirpated, colonies have been successfully reestablished using birds from Florida. Currently, the nesting population numbers over 1,000 pairs. Annual surveys of California brown pelican populations began in the late 1960s. Current estimates indicate that the total population is about 48,500 pairs. Of this total, 3,000 pairs (6%) nest in Southern California; 33,000 (68%) nest in the Gulf of California; 7,500 (15%) nest on islands off mainland Mexico; and 5,000 (10%) nest in southwest Baja California.

Threats

Pesticide pollution presented a double threat to the survival of the brown pelican: direct poisoning and impaired reproduction. Between 1957 and 1961, exposure to concentrations of the pesticide endrin almost eliminated the brown pelican as a breeding species along the Texas and Louisiana coasts. Exposure to the pesticide DDT caused dramatic reproductive failure in brown pelicans on the Gulf, Atlantic, and Pacific coasts. DDT interferes with calcium formation and produces brittle, thin-shelled eggs that are easily crushed during incubation. As a result, the brown pelican was listed as "endangered" throughout its U.S. range in 1970.

In the late 1960s brown pelican populations in South Carolina declined primarily because of egg loss resulting from eggshell thinning. In California, thin-shelled eggs and other complications resulted in almost complete reproductive failure. Out of 375 nests in one colony in 1969, no young were produced. In 1970 a colony on Anacapa Island produced only a single fledgling from 552 nesting pairs. This dramatic decline was caused by the direct dumping of DDT wastes into the Los Angeles sewer system by a pesticide manufacturing plant.

Following publicity about the plight of the brown pelican, human interference in their nesting areas— by both scientists and the public—increased. Human disturbance causes adults to flush, resulting in egg breakage or an increase in predation on unguarded eggs and nestlings. Access to brown pelican colonies is now generally limited to scientific investigators and resource managers on federally owned nesting sites. Even with federal protection for nesting sites, human interference can have a devastating impact—a case in point: Louisiana State biologists had been trying since 1968 to reestablish nesting sites for pelicans on the coast. One site was at the mouth of the Mississippi River in an area known as South Pass, where biologists were trying to encourage the pelicans to use "mud lumps" (small silt formations that naturally rise 6-8 ft [1.8-2.4 m] above the surface of the water) for nesting. In 1989 pelicans nested in this area for the first time since the early 1960s. But on May 30, 1990, four men from a commercial fishing vessel stole 83 eggs from all but one of the pelican nests and from numerous laughing gull (Larus atricilla ) nests. A tip from a concerned citizen and grants from the Izaak Walton League of America and the National Fish and Wildlife Foundation (which funded necessary operational expenses) led to the arrest of the perpetrators, each of whom was sentenced to four months in prison and 200 hours of community service for violating the Endangered Species Act. Although the pelican eggs were recovered, they could not be incubated successfully. Consequently, no young were produced by the colony in 1990. The adult pelicans did not return the following year to nest—a major disappointment to the state biologists. Another threat that has reared its head in recent years is the danger of avian botulism. An outbreak identified in 1996 killed at least 1,125 brown pelicans, 8,525 American white pelicans (Pelecanus erythrorhynchos ), and 4,383 other birds in Southern California's Salton Sea. Preliminary evidence collected by biologists suggested that the bird deaths may be traceable to massive kills of tilapia, an African fish species introduced into the Salton Sea. Avian botulism, which is caused by a toxin produced by the anaerobic bacterium Clostridium botulinum, is considered a disease of waterfowl. It had never before been reported to affect pelicans in such large numbers. Although the link between bacterial infection in tilapia and botulism poisoning in birds is not proven, scientists suspect the bacterial disease may produce conditions in the intestinal tract of sick fish that allow botulism spores to germinate and produce toxin. The spores themselves are likely to be widely present in both the Salton Sea and the fish. The dying fish become easy prey for pelicans, herons, and other fish-eating birds that then ingest fatal doses of toxin. This new danger adds a new dimension and urgency to recovery efforts, not just to restore historic populations but also to preserve the existing ones.

Conservation and Recovery

In 1972 the Environmental Protection Agency placed a ban on the use of DDT in the United States and sharply curtailed the use of endrin. As a result, residue levels of these chemicals have steadily decreased in most areas with a corresponding rise in reproductive success for all brown pelican populations. The eastern brown pelican populations of the Atlantic Coast and the Florida Gulf Coast have since been removed from the federal list of endangered species.

Contacts

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P.O. Box 1306
Albuquerque, New Mexico 87103-1306
Telephone: (505) 248-6911
Fax: (505) 248-6915
http://southwest.fws.gov/

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
Telephone: (404) 679-4000
http://southeast.fws.gov/

Jackson Ecological Services Field Office
6578 Dogwood View Parkway, Suite A
Jackson, Mississippi 39213
Telephone: (601) 965-4900

References

Anderson, D.W., and J.O. Keith. 1980. "The Human Influence on Seabird Nesting Success: Conservation Implications." Biological Conservation 18: 65-80.

Briggs, K.T., and others. 1983. "Brown Pelicans in Central and Northern California." Journal of Field Ornithology 54: 353-373.

King, K.A., and others. 1977. "The Decline of Brown Pelicans on the Louisiana and Texas Gulf Coast." Southwest Naturalist 21 (4): 417-31.

Schreiber, R.W. 1980. "The Brown Pelican: An Endangered Species?" Bioscience 30 (11): 742-747.

U.S. Fish and Wildlife Service. 1983. "The California Brown Pelican Recovery Plan." U.S. Fish and Wildlife Service, Portland.

U. S. Fish and Wildlife Service. 1980. "Eastern Brown Pelican Recovery Plan." U.S. Fish and Wildlife Service, Atlanta.

Brown pelican

The brown pelican (Pelecanus occidentalis ) is a large water bird of the family Pelicanidae that is found along both coasts of the United States, chiefly in saltwater habitats. It weighs up to 8 lb (3.5 kg) and has a wingspan of up to 7 ft (2 m). This pelican has a light brown body and a white head and neck often tinged with yellow. Its distinctive, long, flat bill and large throat pouch are adaptations for catching its primary food, schools of mid-water fishes. The brown pelican hunts while flying a dozen or more feet above the surface of the water, dropping or diving straight down into the water, and using its expandable pouch as a scoop or net to engulf its catch.

Both east and west coast populations, which are considered to be different subspecies, have shown various levels of decline over the later part of the twentieth century. It is estimated that there were 50,000 pairs of nesting brown pelicans along the Gulf coast of Texas and Louisiana in the early part of the twentieth century, but by the early 1960s, most of the Texas and all of the Louisiana populations were depleted. The main reason for the drastic decline was the use of organic pesticides, including DDT and endrin. These pesticides poisoned pelicans directly and also caused thinning of their eggshells. This eggshell thinning led to reproductive failure, because the egg were crushed during incubation. Louisiana has the distinction of being the only state to have its state bird become extinct within its borders. In 1970 the brown pelican was listed as endangered throughout its U.S. range.

During the late 1960s and early 1970s, brown pelicans from Florida were reintroduced to Louisiana, but many of these birds were doomed. Throughout the 1970s these transplanted birds were poisoned at their nesting sites at the outflow of the Mississippi River by endrin, which was used extensively upriver. In 1972 the use of DDT was banned in the U.S., and the use of endrin was sharply curtailed. Continued reintroduction of the brown pelican from Florida to Louisiana subsequently met with greater success, and the Louisiana population had grown to more than 1,000 pairs by 1989. Although the Texas, Louisiana, and California populations are still listed as endangered, the Alabama and Florida populations of the brown pelican have been removed from the federal list due to recent increases in fledgling success. In 2002, taking the Louisiana populations off of the endangered listing is being considered. There are currently 16,4000 nesting pairs and 35,000 young in that state. The Texas population has only 2,400 pairs.

Other problems that face the brown pelican include habitat loss, encroachment by humans, and disturbance by humans. Disturbances have included mass visitation of nesting colonies. This practice has been stopped on federally owned lands and access to nesting colonies is restricted. Other human impacts on brown pelican populations have had a more malicious intent. On the California coast in the 1980s there were cases of pelicans' bills being broken purposefully, so that these birds could not feed and would ultimately starve to death. It is thought that disgruntled commercial fishermen faced with dwindling catches were responsible for at least some of these attacks. The brown pelican was a scapegoat for conditions that were due to weather, pollution , or, most likely, overfishing .

Recovery for the brown pelican has been slow, but progress is being made on both coasts. The banning of DDT in the early 1970s was probably the turning point for this species , and the delisting of the Alabama and Florida populations is a hopeful sign for the future.

[Eugene C. Beckham ]

RESOURCES

BOOKS

Ehrlich, P., D. Dobkin, and D. Wheye. Birds in Jeopardy. Stanford, CA: Stanford University Press, 1992.

PERIODICALS

Schreiber, R. W. "The Brown Pelican: An Endangered Species?" BioScience 30 (November 1980): 742–747.

Tompkins, Shannon. "Brown Pelicans Reappearance Proves Lessons can be Learned." Houston Chronicle (February 14, 2002) [cited May 2002]. <http://www.chron.com/cs/CDA/story.hts/outdoors/tompkins/1256525>.