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Brown Pelican
Pelecanus occidentalis
NatureServe conservation status
Global (G-rank): G4
State (S-rank): SNA
External links
Phenology
Most activity diurnal, little during twilight.
Species range
Breeding range extends along the Pacific coast from southern California to South America and along Atlantic, Gulf, and Caribbean coasts from Maryland south to Florida and westward to southern Texas, plus the Bahamas, West Indies, Yucatan Peninsula, and off Venezuela and the Caribbean coast of Colombia. During the nonbreeding season, brown pelicans range in Pacific coastal waters north to southern British Columbia (after breeding, before winter); in western North America, the species winters mainly from California south; in the southeastern U.S., the primary winter range includes Florida and the Gulf Coast. Subspecies CAROLINENSIS: breeds locally in Maryland and Virginia and south to Florida (primary nesting range), also locally in Louisiana (where reintroduced) and in central coastal Texas; breeds locally also off northeastern Yucatan and Belize, and ranges southward through coastal Honduras and Costa Rica to Panama, where local breeding occurs off the Pacific coast; vagrants wander north to New England and occur casually inland to the Great Lakes and Great Plains states (Johnsgard 1993). Breeds also in the Bahamas (Sprunt 1984) (extirpated, according to Johnsgard 1993). Ranges throughout breeding range and along eastern shores of Mexico south along Central America to the Caribbean coasts of Colombia and Venezuela, and through the Greater and Lesser Antilles to Trinidad; and on the Pacific coast of Central America (AOU 1957).Subspecies CALIFORNICUS: breeds along Pacific coast in southern California (Anacapa Island), and in Mexico on islands off Baja California and on islands in the Gulf of California (south to Isabella and the Tres Marias Islands); possibly locally along the coast of Sonora and Sinaloa; vagrants have occurred north to British Columbia and Idaho (Johnsgard 1993).
Migration
Many stay close to nesting areas in winter. A portion of the eastern subspecies migrates to Florida, the Caribbean coasts of Colombia and Venezuela, and the Greater Antilles for winter. During cold winters, some Texas breeders winter along the Gulf Coast of Mexico. Individuals from breeding areas north of Florida winter mainly in Florida and Cuba; young and adults from Florida breeding colonies are more sedentary (young generally do not disperse more than 250 km from natal areas, adults may move up to 450-575 km from colony during the nonbreeding season) (Johnsgard 1993).
Habitat
Brown pelicans inhabitat mainly coastal waters and rarely are seen inland or far out at sea. They feed mostly in shallow estuarine waters, less often up to 40 miles from shore. They make extensive use of sand spits, offshore sand bars, and islets for nocturnal roosting and daily loafing, especially nonbreeders and during the non-nesting season. Dry roosting sites are essential.Nesting occurs usually on coastal islands, on the ground or in small bushes and trees (Palmer 1962), including the middle or upper parts of steep rocky slopes of small islands in California and Baja California and low-lying islands landward of barrier islands or reefs on the Atlantic and Gulf coasts, where nests often are in mangroves, sometimes in Australian "pines," red-cedars, live oaks, redbays, or sea grapes. In the subtropics and tropics, mangrove vegetation constitutes an important roosting and nesting substrate (Collazo and Klaas 1985, Schreiber 1979, Schreiber and Schreiber 1982). Brown pelican may shift among different breeding sites, apparently in response to changing food supply distribution (Anderson and Gress 1983) and/or to erosion/flooding of nesting sites.
Food habits
Eats mainly fishes, especially menhaden, mullet, sardines, pinfish, and anchovies in U.S. waters; sometimes euphausiids; dives into water from air (USFWS 1980). Feeds by diving in deeper water, by swimming, sometimes in cooperative groups, in shallower water (Hilty and Brown 1986). Rarely reported scavenging or preying on eggs or young of water birds. Forages in shallow estuarine and inshore waters mostly within 10 km of the coast (Johnsgard 1993).
Ecology
Populations fluctuate considerably from year to year and from place to place.
Reproductive characteristics
Along the west coast of North America, egg laying may occur from late winter to early spring (peak usually in March or April but may vary among colonies and from year to year). In southeastern North America, southern populations nest irregularly, usually beginning in late fall and extending through June; northernmost populations nest in spring and summer; intermediate populations nest, somewhat irregularly, in winter and spring. Clutch size averages 2-3. Incubation, by both sexes, lasts about 28-30 days. Young leave ground nests at about 35 days, first fly at 71-88 days; leave nests in mangroves at about 63 days. Some first breed at two years in some colonies (e.g., newly formed ones), possibly not until about four to seven years in stable populations (see Johnsgard 1993). Reproductive success varies with level of disturbance by humans, starvation of young, and/or flooding of nests, but typically the number of young fledged per nest averages one or less. This is a long-lived bird, and reproduction tends to be "boom or bust." Colonies include up to 150 pairs in Trinidad.
Threats or limiting factors
This species was nearly extirpated from North America between the late 1950s and early 1970s when pesticides entering the marine food web caused major population declines. The pesticide endrin killed pelicans directly, whereas DDT reduced reproductive success by causing pelicans to lay thin-shelled eggs that broke during incubation.Populations are extremely vulnerable to chemical/pesticide pollution, which can result in eggshell thinning (reproductive failure) (Anderson and Hickey 1970, Blus et al. 1974), and presumably lethal poisoning. Populations (especially in California, Texas, and Louisiana) were decimated in the U.S. by pesticides (DDT and related compounds) in the 1950s and 60s. In the U.S. Caribbean, 7% of the pelican population in 1982 died as a result of fish die-offs in connection to chemical runoffs (e.g., organophosphates). Other threats include disturbance of nesting birds by humans (reduces reproductive success), declining fish (food) populations, increased turbidity (e.g., from dredging, resulting in reduced visibility of prey); oil and other chemical spills, entanglement in fishing gear, shooting, extreme weather conditions (freezing of soft parts, destruction of nest sites by hurricanes, storms), disease, and parasitism.Human disturbance (e.g., recreational boating, poaching) not only disrupts reproductive success (Anderson and Keith 1980; Schreiber 1979), but may affect distribution patterns and age structure of pelicans using roosting sites during the nonbreeding season (Jaques and Anderson 1987). Habitat degradation affects both roosting and nesting patterns. On the Gulf Coast, nesting efforts have failed because nesting sites are susceptible to flooding as a result of continued site erosion (McNease et al. 1992).Subspecies CALIFORNICUS: Declined greatly due to effects of pesticide contamination in the 1950s and 1960s. In Southern California threatened by pollution (primarily pesticides in food fishes, also oil), human disturbance of breeding colonies, loss or serious decline of food fishes due to human over-fishing (e.g., of anchovies); loss of post-breeding roost sites, fishing gear entanglement, and bacterial infection resulting from overcrowding at fish disposal areas in harbors (California Department of Fish and Game 1990). Human disturbance has decreased nesting success on Islas los Coronados, Mexico (Anderson 1988) and virtually extirpated the breeding colony (California Department of Fish and Game 1990). Southern populations in Mexico have faced problems associated with human disturbance and overexploitation of prey (e.g., sardines), yet they remain stable (D. W. Anderson, pers. comm.).U.S. Caribbean: contaminant levels and availability of nesting habitat are not limiting or affecting the population at present. See Williams et al. (1992) for an account of die-offs that have been observed in Puerto Rico and the Virgin Islands; apparent causes include pesticides, botulism, and unknown factors. In the tropics and subtropics, coastal development and incidental take (e.g., artisanal fishing) is a problem and represents a major threat to the continued availability of mangrove habitat. Close to 91% of all roosting and nesting habitat utilized in the U.S. Caribbean are fringe and overwash mangroves. Fringe mangroves are particularly important to the feeding ecology of pelicans because they provide nutrient inputs and cover for the associated marine community, including food fishes. Both mangrove types are very sensitive to human-created stress such as deforestation, filling and extractions in the salt flats, sedimentation, and oil spills (Cintron and Schaeffer-Novelli 1983). Siltation caused by erosion could be adversely impacting coral reefs, seagrass beds, and mangrove forests (Cintron and Schaeffer-Novelli 1983, Velazco et al. 1985).
