Pelecanidae – Pelicans

The Pelecanidae or Pelicans, are a family and genus of large water birds. They are part of Pelecaniformes along with Ardeidae (Herons, Egrets & Bitterns), Threskiornithidae (Ibises & Spoonbills), Scopidae (Hamerkop) and Balaenicipitidae (Shoebill).

They are characterised 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, the exceptions being the brown and Peruvian pelicans. The bills, pouches and bare facial skin of all species become brightly coloured before the breeding season. The eight living pelican species have a patchy global distribution, ranging latitudinally from the tropics to the temperate zone, though they are absent from interior South America as well as from polar regions and the open ocean. However, 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 (965 km) from the nearest coastline (the Pacific West Coast). They have also been seen hundreds of miles inland in North America, having flown northwards along the Mississippi River and other large waterways.

Great White Pelican Pelecanus onocrotalus – ©DickDaniels CC BY-SA 3.0 via Wikimedia Commons

Long thought to be related to frigatebirds, cormorants, tropicbirds, gannets and boobies, pelicans instead are now known to be part of the order Pelecaniformes that also includes Threskiornidae (Ibises & Spoonbills), Balaenicipitidae (Shoebill), Scopidae (Hamerkop) and Ardeidae (Herons, Egrets & Bitterns). They are most closely related to the shoebill and hamerkop with which they form a clade. On the other hand, Ibises, spoonbills, bitterns and herons are more distant relatives in the same order. Fossil evidence of pelicans, dates back to at least 30 million years to the remains of a beak very similar to that of modern species recovered from Oligocene strata in France. 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 genetic studies of the eight species show they divide into Old World and New World lineages.

Pink-backed Pelican Pelecanus rufescens – ©Dubi Shapiro

Pelicans frequent inland and coastal waters where they feed principally on fish, catching them at or near the water surface. 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. Their populations have fallen through habitat destruction, disturbance and environmental pollution, and three species are of conservation concern.

Australian Pelican Pelecanus conspicillatus – ©Public Domain, via Wikipedia

The eight living pelican species were traditionally divided into two groups, one containing four ground-nesters with mainly white adult plumage (Australian, Dalmatian, Great White, and American White Pelicans), and one containing four grey or brown plumaged species which nest preferentially either in trees (Pink-backed, Spot-billed and Brown Pelicans), or on sea rocks (Peruvian Pelican). The largely marine Brown and Peruvian pelicans, formerly considered conspecific, are now separated from each other.

Peruvian Pelican Pelecanus thagus – ©Dubi Shapiro

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 2.75 kg and 1.06 m long, with a wingspan of as little as 1.83 m. The largest is believed to be the Dalmatian Pelican, at up to 15 kg and 1.83 m in length, with a maximum wingspan of 3 m. The Australian Pelican’s bill may grow up to 0.5 m long in large males, the longest of any bird.

Spot-billed Pelican Pelecanus philippensis – ©Dubi Shapiro

Pelicans have a network of subcutaneous air sacs under their skin situated across the ventral surface including the throat, breast and undersides of the wings, as well as having air sacs in their bones. The air sacs are connected to the airways of the respiratory system, and the pelican can keep its air sacs inflated by closing its glottis, but it is not entirely clear how air sacs are inflated.