The American white pelican is one of the largest of North American birds, and is a majestic sight when flying, soaring with remarkable steadiness on wide black-and-white wings. The large head and huge, heavy bill give this bird a prehistoric look. On water it dips its pouched bill to scoop up fish, tipping up sometimes like an oversized duck looking for food. Groups will work together in order to herd fish into shallow waters for easy feeding. These pelicans migrating in a flock are an impressive sight, being a long line of birds flapping and coasting ponderously. Each bird appears to take the cue from its neighbor in front of it, starting to flap and beginning a glide when the bird in front does. They ride rising air currents up to great heights, to soar gracefully and slowly in circles.
American white pelicans breed in some parts of inland Canada, as well as the northern United States, from Ontario to British Columbia, and from California to Minnesota. Small populations are also found on the central Texan coast and sometimes in parts of Mexico. These birds move south in winter to the Pacific coasts of Central America and the United States, from California to Nicaragua. They also spend the winter near the Gulf Coast, from Florida down to Mexico, perhaps as far to the south as Costa Rica. These pelicans are sometimes also seen on some Caribbean islands. They occur in a range of habitats of freshwater, including bogs, swamps, rivers and lakes, and occasionally saltwater habitats, like estuaries.
The American white pelican migrates annually, apart from several resident populations along the Gulf of Mexico and in Mexico. Juveniles migrate in their first year to the winter range and do not start annual migrations before they have reached 2 years old. Migration in the fall is more dispersed. The birds migrate in formation during the day in large flocks, often more than 180 individuals. Flying gracefully, they spread their wings to slide on their feet onto the water as they land. They fly usually either in linear formations or in a "V" shape. They glide and flap and may soar on some days when they are able to take advantage of updrafts. These pelicans do not dive, but are strong swimmers, having subcutaneous air sacs in their breast that afford them buoyancy. Being gregarious, these birds are always found in groups when roosting, nesting, or foraging. Nesting colonies are very big and densely populated, often with around 1,000 nests.
American white pelicans are serially monogamous and form pairs for one breeding season. Pairs form through courtship rituals once they arrive at the breeding colony. During these displays, to attract a mate, the birds show off their bright orange bills, strut around, bow and take short flights. Mating runs from late March until early May. The birds breed in large colonies of up to 5,000 pairs on a site on peninsulas or islands in undisturbed areas. Nests are built by both parents on the ground in a shallow depression, using sticks and twigs. 2 eggs are laid and incubation is by both members of the pair, for about 29 to 36 days. They both feed the altricial (naked and helpless) chicks, by regurgitating food, but usually only one chick fledges, at around 17 to 28 days, still flightless at that stage. Within their colony, young gather in groups. They start migrating when they are 10 to 11 weeks old, just one week after making their first flight. They reach maturity in 3 to 4 years, when they develop large ridges in their beaks, called “nuptial tubercles”, and ornamental feathers on their head.
These shy pelicans used to be shot for sport or because it was considered that they competed for fish with humans. As their numbers have increased, in spring their migration stopovers in the Mississippi Delta at catfish aquaculture ponds have also increased, and there have been more shootings there. Historically, destruction of breeding and foraging habitat and human disturbance have been major threats. These birds are also vulnerable to toxic pollutants from eating contaminated prey, which can cause eggshells to be thinner and thus reduce reproductive success. Another threat is the reduction of suitable breeding sites due to the drainage of lakes of the flooding of nesting islands.
According to the IUCN Red List, American white pelican has an extremely large range, and the total population size of this species is 180,000 individuals. Currently this species is classified as Least Concern (LC) and its numbers today are increasing.