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How small is the white-tailed tropic bird compared with other pelecaniforms?

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Three eastern white pelicans with black-tipped wings take off from a muddy shoreline, wings outstretched, with blurred green vegetation in the background. — Pelecaniform European white pelicans (*Pelecanus onocrotalus*) in flight.

The white-tailed tropic bird (Phaethon lepturus) is the smallest member of the order Pelecaniformes, measuring approximately 40 cm (about 16 inches) in length, excluding its elongated central tail feathers.1

Compared to other pelecaniforms, which are generally considered large birds, the white-tailed tropic bird represents the lower end of the size spectrum. The order includes significantly larger species, such as the Dalmatian pelican, which can reach lengths of up to 1.8 metres (6 feet). While traditionally grouped within this order, it is worth noting that modern molecular genetic analyses suggest that tropic birds are only distantly related to other pelecaniforms and may belong to their own distinct order, Phaethontiformes.12