The back, rump, and tail are streaked with gray and dark brown, sometimes with a rusty hue. The male and female are similar, but the female is slightly smaller. The nonbreeding adult has a white head and neck, and the pre-breeding adult has a creamy yellow head. The pink skin around the eyes becomes dull and gray in the non-breeding season. It lacks any red hue, and the pouch is strongly olivaceous ochre-tinged and the legs are olivaceous gray to blackish-gray. It has pale blue to yellowish-white irides which become brown during the breeding season. During courtship, the bill becomes pinkish red to pale orange, redder at the tip, and the pouch is blackish. Later in the breeding season, the bill becomes pale ash-gray over most of the upper jaw and the basal third of the mandible. The Brown pelican is exceptionally buoyant due to the internal air sacks beneath its skin and in its bones. It is as graceful in the air as it is clumsy on land.
The Brown pelican (Pelecanus occidentalis) has been described as a comically elegant bird. Groups of these seabirds glide above surf along western and southern coasts, gracefully echoing the waves with their rise and fall. They plunge-dive from high up to feed, the force of impact serving to stun small fish, which they then scoop up. Today this species is fairly common - a good example of recovery from the pesticide pollution that once threatened them with extinction.
The Brown pelican is the smallest of the eight extant pelican species but is often one of the larger seabirds in their range nonetheless. Like all pelicans, it has a very long bill, measuring 280 to 348 mm (11.0 to 13.7 in) in length. The nominate subspecies in its breeding plumage has a white head with a yellowish wash on the crown. The nape and neck are dark maroon–brown. The upper sides of the neck have white lines along the base of the gular pouch, and the lower foreneck has a pale yellowish patch. The feathers at the center of the nape are elongated, forming short, deep chestnut crest feathers. It has a silvery gray mantle, scapulars, and upperwing coverts (feathers on the upper side of the wings), with a brownish tinge. The lesser coverts have dark bases, which gives the leading edge of the wing a streaky appearance.
The uppertail coverts (feathers above the tail) are silvery white at the center, forming pale streaks. The median (between the greater and the lesser coverts), primary (connected to the distal forelimb), secondary (connected to the ulna), and greater coverts (feathers of the outermost, largest, row of upperwing coverts) are blackish, with the primaries having white shafts and the secondaries having variable silver-gray fringes. The tertials (feathers arising in the brachial region) are silver-gray with a brownish tinge. The underwing has grayish-brown remiges with white shafts to the outer primary feathers. The axillaries and covert feathers are dark, with a broad, silver–gray central area. The tail is dark gray with a variable silvery cast. The lower mandible is blackish, with a greenish-black gular pouch at the bottom for draining water when it scoops out prey. The breast and belly are dark, and the legs and feet are black. It has a grayish-white bill tinged with brown and intermixed with pale carmine spots. The crest is short and pale reddish-brown in color.
The Brown pelican occurs throughout the Pacific, Atlantic, and Gulf Coasts of the Americas. Most brown pelican populations are resident (nonmigratory) and dispersive (moving from their birth site to their breeding site, or their breeding site to another breeding site); however, some populations migrate, depending on local conditions. Brown pelicans are strictly marine and coastal birds but occasionally follow large rivers during storms. They avoid the open sea and rarely occur far offshore, usually frequenting shallow waters along coasts, as well as estuaries and bays. They breed on the arid coasts of flat, bare, remote islands, or occasionally in mangroves. Brown pelicans can often be seen around fishing ports.
Brown pelicans, after bathing, use their beaks to spread oil from the uropygial gland over their feathers.
Courtship displays by Brown pelicans usually last 2-4 days, but sometimes as long as three weeks.
Brown pelicans incubate their eggs by means of their webbed feet, turning the eggs from time to time.
Brown pelicans are the only type of pelican that dive in order to catch prey. They glide low above the water and when they see a fish they fly to a height of 10 m (30 ft), fold their wings back, and plunge down into the sea.
Brown pelicans do exercises, including stretching and turning their pouch inside out to maintain its flexibility.
Brown pelicans are very gregarious and live throughout the year in flocks. They are diurnal but sometimes forage at night during a full moon. They sleep on land either while standing on both their feet or resting on their breast and belly, their head sideways on their shoulder with their beak tilted towards the side. This is the only pelican species that dives from height as the main method of obtaining food. Their air sacs enable buoyancy for them in the water. They do not swim under the water but plunge their head below the surface when catching prey. Brown pelicans are territorial during the nesting period. Threat displays, often carried out when another pelican is too close to an individual’s nest involve head swaying, indicating readiness to interact, and bowing and a "hrraa-hrraa" sound. Young pelicans who approach a nest too closely are often killed.
Brown pelicans do not have many natural enemies. Although nests on the ground are sometimes destroyed by flooding, hurricane, or other natural disasters, people pose the biggest threat to pelicans. In the early 20th and late 19th centuries, pelicans’ feathers were sought after to adorn women’s clothing, especially hats. Today tourists and fishermen threaten them by disturbing their colonies, especially in Mexico.
