Pelican
Pelicans are a genus of large water birds that make up the family Pelecanidae. They are characterized by a long beak and a large throat pouch used for catching prey and draining water from the scooped-up contents before swallowing. They have predominantly pale plumage, except for the brown and Peruvian pelicans. The bills, pouches, and bare facial skin of all pelicans become brightly coloured before the breeding season.
The eight living pelican species have a patchy, seasonally-dependent yet global distribution, ranging latitudinally from the tropics to the temperate zone. Pelicans are absent from interior Amazonian South America, from polar regions and the open ocean; at least one species is known to migrate to the inland desert of Australia's Red Centre, after heavy rains create temporary lakes. White pelicans are also observed at the American state of Utah's Great Salt Lake, for example, some 600 miles from the nearest coastline. They have also been seen hundreds of miles inland in North America, having flown northwards along the Mississippi River and other large waterways.
Long thought to be related to frigatebirds, cormorants, tropicbirds, and gannets and boobies, pelicans instead are most closely related to the shoebill and hamerkop storks, and are placed in the order Pelecaniformes. Ibises, spoonbills, herons, and bitterns have been classified in the same order. Fossil evidence of pelicans dates back at least 36 million years to the remains of a tibiotarsus recovered from late Eocene strata of Egypt that bears striking similarity to modern species of pelican. They are thought to have evolved in the Old World and spread into the Americas; this is reflected in the relationships within the genus as the eight species divide into Old World and New World lineages. This hypothesis is supported by fossil evidence from the oldest pelican taxa.
File:Pelicans at National Zoo.jpg|thumb|Pelicans at National Zoo, Bangladesh
Pelicans will frequent inland waterways but are most known for residing along maritime and coastal zones, where they feed principally on fish in their large throat pouches, diving into the water and catching them at/near the water's surface. They can adapt to varying degrees of water salinity, from freshwater and brackish to—most commonly—seawater. They are gregarious birds, travelling in flocks, hunting cooperatively, and breeding colonially. Four white-plumaged species tend to nest on the ground, and four brown or grey-plumaged species nest mainly in trees. The relationship between pelicans and people has often been contentious. The birds have been persecuted because of their perceived competition with commercial and recreational fishing. Their populations have fallen through habitat destruction, disturbance, and environmental pollution, and three species are of conservation concern. They also have a long history of cultural significance in mythology, and in Christian and heraldic iconography.
Taxonomy and systematics
Etymology
The name comes from the Ancient Greek word pelekan, which is itself derived from the word pelekys meaning "axe". In classical times, the word was applied to both the pelican and the woodpecker.Taxonomy history
The genus Pelecanus was first formally described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae. He described the distinguishing characteristics as a straight bill hooked at the tip, linear nostrils, a bare face, and fully webbed feet. This early definition included frigatebirds, cormorants, and sulids, as well as pelicans. The family Pelecanidae was later introduced by the French polymath Constantine Samuel Rafinesque in 1815.Order and related taxa
Pelicans give their name to the Pelecaniformes, an order which has undergone significant revision. Tropicbirds, darters, cormorants, gannets, boobies, and frigatebirds, all traditional members of the order, have since been removed from Pelecaniformes. In their place, herons, ibises, spoonbills, the hamerkop, and the shoebill have now been added into the Pelecaniformes.Phylogenetic relationships
Molecular data support a close relationship between pelicans, shoebills, and hamerkops. Together, they form a distinct clade within Pelecaniformes, although their precise evolutionary relationships remain under study.Evolution and fossil record
The oldest known pelican fossil is Eopelecanus aegyptiacus, a tibiotarsus from the late Eocene the Birket Qarun Formation in the Wadi El Hitan in Egypt. It shows striking similarities with modern species.Later fossils from the Early Miocene found at Luberon, France, include Pelecanus sp. and Miopelecanus gracilis. Both fossils show a beak nearly morphologically identical to that of present-day pelicans. This remarkable stasis in pelican beak morphology may reflect strong functional constraints. Their specialized fish-eating beak has likely remained optimal over millions of years, with changes potentially reducing feeding efficiency. Some have also suggested that constraints imposed by flight may have limited the skeletal evolution of pelicans.
Notable fossil species include:
- Europe: P. fraasi, Lydekker, 1891; P. intermedius, Frass,1870; P. gracilis, Milne-Edwards, 1863; P. odessanus, Widhalm, 1886
- North America: P. halieus, Wetmore, 1933; P. schreiberi, Olson, 1999
- Asia: P. cautleyi, Davies, 1880; P. sivalensis, Davies, 1880
- South America: P. paranensis, Noriega et al., 2023
- Australia: P. cadimurka, Rich & van Tets, 1981; P. tirarensis, Miller, 1966
Controversial and dubious fossil assignments
- Protopelicanus – Once considered a possible early pelecaniform, this bird might instead belong to the Pelagornithidae or another unrelated aquatic lineage. It is not generally accepted as a member of Pelecanidae.
- Liptornis – Originally described as a pelican, this genus is now considered a nomen dubium, based on fragmentary material that lacks sufficient diagnostic features.
Extant species and phylogeny
Species overview
There are eight extant species of pelicans, which were historically divided into two groups based on plumage colouration and nesting behavior. One group includes four ground-nesting species with predominantly white plumage—the Australian, Dalmatian, great white, and American white pelicans. The other group consists of four species with grey or brown plumage that nest either in trees or on coastal rocks—the pink-backed, spot-billed, brown, and Peruvian pelicans. The largely marine brown and Peruvian pelicans, once considered conspecific, are sometimes placed in the subgenus Leptopelecanus due to their darker colouration and coastal habits. However, species with similar plumage and nesting behavior are found in both groups, indicating that these traits do not reflect deep evolutionary divisions.Genetic analyses using mitochondrial and nuclear DNA have revealed a different picture of pelican relationships. These studies support the existence of two major clades: a New World clade, comprising the American white, brown, and Peruvian pelicans, and an Old World clade that includes the Dalmatian, pink-backed, spot-billed, Australian, and great white pelicans. This phylogeny suggests that pelicans evolved in the Old World and later colonized the Americas. Furthermore, it indicates that nesting behavior is more strongly influenced by body size than by genetic lineage.
List of living species
Description
Pelicans are very large birds with very long bills characterised by a downcurved hook at the end of the upper mandible, and the attachment of a huge gular pouch to the lower. The slender rami of the lower bill and the flexible tongue muscles form the pouch into a basket for catching fish, and sometimes rainwater, though to not hinder the swallowing of large fish, the tongue itself is tiny. They have a long neck and short stout legs with large, fully webbed feet. Although they are among the heaviest of flying birds, they are relatively light for their apparent bulk because of air pockets in the skeleton and beneath the skin, enabling them to float high in the water. The tail is short and square. The wings are long and broad, suitably shaped for soaring and gliding flight, and have the unusually large number of 30 to 35 secondary flight feathers.Males are generally larger than females and have longer bills. The smallest species is the brown pelican, small individuals of which can be no more than and long, with a wingspan of as little as. The largest is believed to be the Dalmatian pelican, at up to and in length, with a maximum wingspan of. The Australian pelican's bill may grow up to long in large males, the longest of any bird.
Pelicans have mainly light-coloured plumage, the exceptions being the brown and Peruvian pelicans. The bills, pouches, and bare facial skin of all species become brighter before breeding season commences. The throat pouch of the Californian subspecies of the brown pelican turns bright red, and fades to yellow after the eggs are laid, while the throat pouch of the Peruvian pelican turns blue. The American white pelican grows a prominent knob on its bill that is shed once females have laid eggs. The plumage of immature pelicans is darker than that of adults. Newly hatched chicks are naked and pink, darkening to grey or black after four to 14 days, then developing a covering of white or grey down.