Pelecanus erythrorhynchos

Geographic Range

American white pelicans are found throughout North America. They breed in inland, prairie regions of the United States and Canada and winter in southern and coastal areas. Breeding occurs in suitable habitat from British Columbia, Alberta, Saskatchewan, Manitoba, and southwestern Ontario south through northern California, Nevada, and Colorado. They winter in southern California, coastal and eastern Mexico, the coastal plain of Texas, and throughout the Gulf states, including Florida. Populations that breed mostly east of the continental divide tend to migrate to winter ranges in the Gulf of Mexico, breeding populations west of the continental divide tend to migrate towards Baja California and western Mexico. There are several, small year-round populations along the Gulf of Mexico and in central Durango, Mexico. The winter range is characterized by minimum January temperatures above 4 degrees Celsius.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

American white pelicans winter in coastal areas, such as coastal bays and estuaries. Significant inland wintering areas are the Salton Sea in California and large rivers in areas where water flow prevents freezing. They breed on islands in or near shallow, inland lakes, rivers, and marshes. Islands can be either permanent islands in freshwater water bodies or temporary islands in wetlands. These temporary nesting and roosting habitats can be important in determining breeding and winter distribution. Breeding islands are commonly more than 50 km from areas used for foraging. American white pelicans migrate over inland areas with large lakes and rivers for resting and foraging.

• Habitat Regions
• temperate temperate
• tropical tropical
• saltwater or marine saltwater or marine
• freshwater freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• coastal coastal
• brackish water brackish water

• Wetlands
• marsh marsh

• Other Habitat Features
• estuarine estuarine

Physical Description

American white pelicans are large, white pelicans, there are no similar species in North America. Their primary and outer secondary feathers are black, their bill and gular pouch are flesh colored or yellow, and their legs are pale yellow to bright orange. Both males and females develop a flattened protuberance on the upper bill during breeding season, which is shed at the end of breeding. American white pelicans are from 127 to 165 cm in length. The other North American pelican species, brown pelicans , are smaller, with dark plumage. Males are slightly larger than females. Their wingspan is from 244 to 290 and reported masses are from 4.54 to 9 kg. There are no described subspecies or geographic variation.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

American white pelicans form monogamous pairs in breeding season and defend small nesting territories in breeding colonies. Pair bonds form on arrival at the breeding colony through courtship rituals. These courtship displays include a circular courtship flight, parallel strutting walks, head swaying, and bowing. Bonds last through most of the breeding season, but whether pairs reform in subsequent years is unknown. Males guard female mates, although extra-pair copulations seem rare.

• Mating System
• monogamous monogamous

Once the bulk of birds arrive on the breeding grounds, pairs begin to form and breed. Mating occurs from late March through early May. Once a pair has formed, they begin to establish and defend a nest scrape. This process is highly synchronous in colonies, with nests being established over the course of about a week. Nests are simple scrapes with low rims on bare, level ground that are accessible to flying pelicans. Nest sites typically have little vegetation, but may be among low shrubs, weeds, or grass. They have 1 brood each year, laying 2 chalky-white eggs 2 days apart. If an egg is lost, it is not replaced. If both are lost, the nest is deserted. Eggs are incubated continuously under the foot webs of parents for about 30 days and brooded for about 17 days further. Young are fed by regurgitation by parents until the young leaves the colony at fledging, usually at 10 to 11 weeks after hatching. American white pelicans begin breeding at 3 years old.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Both parents incubate eggs, taking turns every 72 hours. When brooding, parents exchange places about every day.

• Parental Investment
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • protecting
    • male
    • female

Lifespan/Longevity

American white pelicans typically successfully raise just 1 of the 2 eggs they lay. Only 9.7% of clutches in one colony successfully raised 2 young to fledgling. Average mortality of that offspring through its first year of life is 41%. Average mortality from the 1st to 2nd year is 16%, and average mortality drops after that. The oldest recorded American white pelican in the wild was 26.4 years old. Nestlings and eggs die as a result of rolling out of nests, nest abandonment, starvation, attacks by other pelicans in the nesting colony, exposure, and predation. Adults are killed by severe weather, hitting wires, and diseases such as botulism.

Behavior

American white pelicans migrate annually, except for a few resident populations in Mexico and along the Gulf of Mexico. Juveniles migrate to the winter range their first year and don't begin annual migrations until they are 2 years old. American white pelicans arrive on the breeding grounds in the spring over a relatively short period, usually arriving by March or early April. Fall migration is more dispersed. They migrate during the day in formation in large flocks, often over 180 individuals.

American white pelicans fly gracefully, spreading their wings and sliding onto the water on their feet as they land. Flight is usually in linear formations or forming a "V." They flap and glide and may soar on days when they can take advantage of updrafts. American white pelicans don't dive, as do their relatives, brown pelicans , but they are strong swimmers and have subcutaneous air sacs in the region of their breast that give them buoyancy. They are gregarious birds, always found roosting, nesting, or foraging in groups. Nesting colonies are very large and densely populated, often around 1000 nests.

• Key Behaviors
• flies
• natatorial natatorial
• diurnal diurnal
• motile motile
• migratory migratory
• sedentary sedentary
• territorial territorial
• social social
• colonial colonial

Home Range

American white pelicans defend small nesting territories in breeding colonies, often jabbing at their neighbors, including other species of nesting waterbirds ( Phalacrocorax auritus , Larus ). Nests may be only 1 m apart. They do not have defined home ranges, instead ranging widely throughout the non-breeding season to forage and roost.

Communication and Perception

Adult American white pelicans are relatively silent, only using low grunts when in aggressive or sexual interactions. Young pelicans squawk loudly to beg for food. American white pelicans use a variety of visual displays to communicate aggression, appeasement, and alarm. They will jab at others with their bill or extend their gaped mouth towards them, usually in aggressive interactions around territories or mating. They hold their head upright with the bill extended horizontally and the gular pouch expanded, accompanied by a grunt, as a greeting or mild threat. In flight over colonies they stop flapping briefly and hold the bill down as another mild threat. Crouching or bowing is an appeasement display in young and adults. Courtship includes several visual displays in the air and on the ground, including circular courtship flights above the colony, parallel strutting displays between pairs, bowing, and head swaying between mates at the nest.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

American white pelicans forage in shallow waters for fish, crustaceans, and amphibians. They may also forage in deeper waters where fish occur near the surface. They forage during the day typically, but may forage at night during the breeding season. They forage alone or in cooperative groups, they dip their bills into the water while swimming at the surface and scoop prey into their bill and gular pouch. Cooperative foraging groups may collaborate to drive prey into shallow waters to make it more difficult for them to escape capture. Individuals that forage in groups tend to have greater foraging success. Plunge-diving, as in brown pelicans , has only been rarely observed in these pelicans. They will also take prey from other pelicans or waterbirds, including double-crested cormorants , gulls , and other pelicans. American white pelicans eat mainly small, schooling fish, although they also eat crayfish and amphibians on inland lakes and rivers in the breeding season. Fish recorded in the diet include carp , minnows , tui chub , and occasionally game fish, such as salmon .

• Primary Diet
• carnivore carnivore
  • piscivore piscivore

• Animal Foods
• amphibians
• fish
• aquatic crustaceans

Predation

Breeding colonies on isolated islands help to lessen the threat of terrestrial predators on American white pelican young and eggs. Red foxes and coyotes are threats to breeding colonies that are accessible. Gull species prey on eggs and young, including herring gulls , California gulls , and ring-billed gulls . Also, common ravens prey on eggs and great horned owls and bald eagles take young. Adult size may lessen the risk of predation, but coyotes have been known to take adults. Although American white pelicans readily forage and loaf near humans, they are easily disturbed from nests, abandoning their young readily when a threat is perceived. Gulls take advantage of this to attack exposed nestlings. They also attack nestlings that have wandered from the nest or been expelled by an older sibling. Gulls also take food from young if they empty their stomach contents after being disturbed. These pelicans don't leave the nest in response to avian predators, instead jabbing at them with their bills.

Ecosystem Roles

American white pelicans often breed in colonies along with double-crested cormorants , gull species , Canada geese , great blue herons , common terns , and Caspian terns .

American white pelicans suffer from infestations of biting lice ( Piagetiella peralis ), especially around their mouth and gular pouch. Nematodes ( Contracaecum spiculigerum ) and tape worms (tape worms Hymenolepis species, Dibothrium cordiceps , Oilgorchis longivaginatus ) have been reported from guts. One individual was infested with subcutaneous mites ( Pelecanectes apunctatus ).

Economic Importance for Humans: Positive

American white pelicans are lovely, majestic birds that are appreciate by bird enthusiasts. Historically they were also hunted for sport.

Economic Importance for Humans: Negative

There are no known adverse effects of American white pelicans on humans. They were previously persecuted because of the misperception that they compete with humans for fish prey, but American white pelicans eat mainly small fish with no commercial value.

Conservation Status

There have been documented increases in American white pelican populations in recent years, resulting from conservation efforts. Historically populations declined in response to destruction of breeding and foraging habitats and continued destruction of wetland habitats remains one of the most important influences on current populations. American white pelicans are especially sensitive to human disturbance at nesting sites, where human presence can result in temporary or permanent nest abandonment, increasing the likelihood of mortality associated with exposure and gull predation. Common human disturbances at nesting colonies are low-flying airplanes or motorboats. Pesticide use throughout their range has resulted in egg-shell thinning and poisoning. They are considered least concern by the IUCN because of their large population sizes and broad range.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (author), Animal Diversity Web.

References

Knopf, F., R. Evans. 2004. American White Pelican (Pelecanus erythrorhynchos). The Birds of North America Online , 57: 1-20. Accessed May 06, 2009 at http://bna.birds.cornell.edu/bna/species/057 .