Pelicans, cormorants and allies

About

The Pelecaniformes are a (possibly invalid) order of medium-sized and large waterbirds found worldwide. As traditionally – but erroneously – defined, they encompass all birds that have feet with all four toes webbed. Hence, they were formerly also known by such names as totipalmates or steganopodes. Most have a bare throat patch (gular patch), and the nostrils have evolved into dysfunctional slits, forcing them to breathe through their mouths. They feed on fish, squid or similar marine life. Nesting is colonial, but individual birds are monogamous. The young are altricial, hatching from the egg helpless and naked in most. They lack a brood patch.

In the all-encompassing "steganopode" circumscription, the Pelecaniformes had some 50-60 living species. However, modern opionion considers the apparent similarities the result of convergent evolution, and based on a wealth of evidence splits the classically defined "Pelecaniformes" into several groups. Most lineages – frigatebirds, gannets, cormorants and anhingas – constitute indeed a natural group, for which the name Phalacrocoraciformes has been proposed. Tropicbirds are of unclear relationships, but appear to be a quite distinct lineage; they are typically placed in an own order today. The pelicans, meanwhile, are linked to the storks by two bizarre monotypic families, the Hammerkop (Scopidae) and the Shoebill (Balaenicipitidae). Indeed, they may be closer related to storks than these are to herons. To overcome this confusion, it has been proposed to merge the "core" Pelecaniformes into the Ciconiiformes.

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