the american white pelican (pelecanus erythrorhynchos) is a large aquatic bird from the order pelecaniformes .
it breeds in interior north america , moving south and to the coasts , as far as central america , in winter .
the scientific name means "red-billed pelican", from the latin term for a pelican , pelecanus , and erythrorhynchos , derived from the ancient greek wordsthe american white pelican rivals the trumpeter swan , with a similar overall length , as the longest bird native to north america .
both very large and plump , it has an overall length of about 5070 in (130180 cm), courtesy of the huge beak which measures 11.315.2 in (290390 mm) in males and 10.314.2 in (260360 mm) in females .
it has a wingspan of about 95120 in (240300 cm) .
the species also has the second largest average wingspan of any north american bird , after the california condor .
this large wingspan allows the bird to easily use soaring flight for migration .
body weight can range between 7.7 and 30 lb (3.5 and 13.6 kg), although typically these birds average between 11 and 20 lb (5.0 and 9.1 kg) .
one mean body mass of 15.4 lb (7.0 kg) was reported .
another study found mean weights to be somewhat lower than expected , with eleven males averaging 13.97 lb (6.34 kg) and six females averaging 10.95 lb (4.97 kg) .
among standard measurements , the wing chord measures 2026.7 in (5168 cm) and the tarsus measures 3.95.4 in (9.913.7 cm) long .
the plumage is almost entirely bright white , except the black primary and secondary remiges , which are hardly visible except in flight .
from early spring until after breeding has finished in mid-late summer , the breast feathers have a yellowish hue .
after moulting into the eclipse plumage , the upper head often has a grey hue , as blackish feathers grow between the small wispy white crest .
the bill is huge and flat on the top , with a large throat sac below , and , in the breeding season , is vivid orange in color as are the iris , the bare skin around the eye , and the feet .
in the breeding season , there is a laterally flattened "horn" on the upper bill , located about one-third the bill's length behind the tip .
this is the only one of the eight species of pelican to have a bill "horn" .
the horn is shed after the birds have mated and laid their eggs .
outside the breeding season the bare parts become duller in color , with the naked facial skin yellow and the bill , pouch , and feet an orangy-flesh color .
apart from the difference in size , males and females look exactly alike .
immature birds have light grey plumage with darker brownish nape and remiges .
their bare parts are dull grey .
chicks are naked at first , then grow white down feathers all over , before moulting to the immature plumage .
it is a very large and plump bird; its overall length is about 5067 inches (130170 cm), courtesy of the huge beak which measures 1314.4 inches (330370 mm) in males and 10.413 in (260330 mm) in females .
it has a wingspan of about 95120 in (240300 cm), making it the second largest wingspan of any north american bird after the california condor  .
body weight can range between 10 and 30 lb (4.5 and 14 kg), although typically these birds average between 11 and 20 lb (5.0 and 9.1 kg) .
the plumage is almost entirely bright white , except the black primary and secondary remiges , which are hardly visible except in flight .
from early spring until after breeding has finished in mid-late summer , the breast feathers have a yellowish hue .
after moulting into the eclipse plumage , the upper head often has a grey hue , as blackish feathers grow between the small wispy white crest .
the bill is long and flat , with a large throat sac , and in the breeding season vivid orange like the iris , the bare skin around the eye , and the feet .
in the breeding season , there is a laterally flattened "horn" on the upper bill , about one-third the bill's length behind the tip .
this is shed off after the birds have mated and laid their eggs , and outside the breeding season the bare parts become duller in color , with the naked facial skin yellow and the bill , pouch and feet an orangy-flesh color .
apart from the difference in size , males and females look exactly alike .
immature birds have light grey plumage with darker brownish nape and remiges .
their bare parts are dull grey .
hatchlings are naked at first , then grow white down feathers all over , before moulting to the immature plumage .
american white pelicans nest in colonies of several hundred pairs on islands in remote brackish and freshwater lakes of inland north america .
the most northerly nesting colony can be found on islands in the rapids of the slave river between fort fitzgerald , alberta , and fort smith , northwest territories .
about 1020% of the population uses gunnison island in the great basin's great salt lake as a nesting ground .
the southernmost colonies are in southwestern ontario and northeastern california .
nesting colonies exist as far south as albany county in southern wyoming .
they winter on the pacific and gulf of mexico coasts from central california and florida south to panama , and along the mississippi river at least as far north as st .
louis , missouri .
in winter quarters , they are rarely found on the open seashore , preferring estuaries and lakes .
they cross deserts and mountains but avoid the open ocean on migration .
but stray birds , often blown off course by hurricanes , have been seen in the caribbean .
in colombian territory it has been recorded first on february 22, 1997, on the san andrs island , where they might have been swept by hurricane marco which passed nearby in november 1996. since then , there have also been a few observations likely to pertain to this species on the south american mainland , e .
g .
at calamar .
wild american white pelicans may live for more than 16 years .
in captivity , the record lifespan stands at over 34 years .
unlike the brown pelican (p .
occidentalis), the american white pelican does not dive for its food .
instead it catches its prey while swimming .
each bird eats more than 4 pounds of food a day , mostly fish such as cypriniformes like common carp (cyprinus carpio), lahontan tui chub (gila bicolor obesa) and shiners , perciformes like sacramento perch (archoplites interruptus) or yellow perch (perca flavescens), salmoniformes like rainbow trout (oncorhynchus mykiss), siluriformes (catfish), and jackfish .
other animals eaten by these birds are crayfish and amphibians .
birds nesting on saline lakes , where food is scarce , will travel great distances to better feeding grounds .
american white pelicans like to come together in groups of a handful of birds or so to feed , as they can thus cooperate and chase fish to one another .
when this is not easily possible  for example in deep water , where fish can escape by diving out of reach , they prefer to forage alone .
but the birds also steal food on occasion , sometimes from other pelicans , sometimes from gulls .
as noted above , they are colonial breeders , with up to 5,000 pairs per site .
the birds arrive on the breeding grounds in march or april; nesting starts between early april and early june .
the nest is a shallow depression scraped in the ground , in some twigs , sticks , reeds or similar debris have been gathered .
after about one week of courtship and nest-building , the female lays a clutch of usually 2 or 3 eggs , sometimes just one , sometimes up to six .
both parents incubate for about 4 weeks to one month .
the young leave the nest 34 weeks after hatching; at this point , usually only one young per nest has survived .
they spend the following month in a creche or "pod", moulting into immature plumage and eventually learning to fly .
after fledging , the parents care for their offspring some three more weeks , until the close family bond separates in late summer or early fall , and the birds gather in larger groups on rich feeding grounds in preparation for the migration to the winter quarters .
they migrate south by september or october .
occasionally , these pelican may nest in colonies on isolated islands , which is believed to significantly reduce the likelihood of mammalian predation .
red foxes and coyotes readily predate colonies that they can access , the later being the only known species to hunt adult pelicans (which are too large for most bird predators to subdue) .
several gulls have been known to predate pelican eggs and nestlings (including herring , ring-billed and california gull), as well as common ravens .
young pelicans may be hunted by great horned owls and bald eagles .
the pelicans react differently to mammalian threats as opposed to avian threats .
though fairly approachable while feeding , the pelicans may temporarily abandon their nests if a human or other large mammal closely approaches the colony .
if the threat is another bird , however , the pelicans do not abandon the nest and may fight off the interloper by jabbing at them with their considerable bills .
this species is protected by the migratory bird treaty act of 1918. it has the california department of fish and game protective status california species of special concern (csc) .
on a global scale however , the species is common enough to qualify as a species of least concern according to the iucn .
habitat loss is the largest known cause of nesting failure , with flooding and drought being recurrent problems .
human-related losses include entanglement in fishing gear , boating disturbance and poaching as well as additional habitat degradation .
there was a pronounced decline in american white pelican numbers in the mid-20th century , attributable to the excessive spraying of ddt , endrin and other organochlorides in agriculture as well as widespread draining and pollution of wetlands .
but populations have recovered well after stricter environmental protection laws came into effect , and are stable or slightly increasing today .
by the 1980s , more than 100,000 adult american white pelicans were estimated to exist in the wild , with 33,000 nests altogether in the 50 colonies in canada , and 18,500 nests in the 14-17 united states colonies .
shoreline erosion at breeding colonies remains a problem in some cases , as are the occasional mass poisonings when pesticides are used near breeding or wintering sites .
