Petrel
Petrels are tube-nosed seabirds in the phylogenetic order Procellariiformes.
Description
Petrels are a monophyletic group of marine seabirds, sharing a characteristic of a nostril arrangement that results in the name "tubenoses". Petrels encompass three of the four extant families within the Procellariiformes order, namely Procellariidae, Hydrobatidae, and Oceanitidae. The remaining family in Procellariiformes is the albatross family, Diomedeidae.Etymology
The word petrel comes from likely earlier pitteral or pittrel, and refers to the way the storm petrel patters with its feet over the sea surface. The English explorer William Dampier wrote the bird was so called from its way of flying with its feet just skimming the surface of the water, recalling Saint Peter's walk on the sea of Galilee, being formed in English as a diminutive of Peter ; this connection is however due to later speculation.Known species
All the members of the order are exclusively pelagic in distribution, returning to land only to breed.The family Hydrobatidae comprises the northern storm petrels, the "true" petrels of the Northern Hemisphere, characterised by very small size, pattering flight while feeding, and strictly nocturnal behaviour when visiting their breeding sites on remote islands. The 18 species currently accepted are now all included in the genus Hydrobates, after the former genus Oceanodroma was shown to be paraphyletic with respect to Hydrobates. Despite their tiny size, they are remakably long-lived, with European storm petrel known to exceed 38 years even though only weighing 20–30 g.
The family Procellariidae is the main radiation of medium-sized petrels and shearwaters, characterised by united nostrils with medium septum, and a long outer functional primary feather. It is dominant in the Southern Oceans, but less so in the Northern Hemisphere.
It includes a number of petrel groups, the relationships between which have finally been resolved to satisfaction.
- The fulmarine petrels: seven species of surface predators and filter feeders, breed in high latitudes but migrate along cool currents to the north. All but Fulmarus are essentially confined to the south, Fulmarus apparently colonised the Northern Hemisphere during the Early Miocene.
- * The huge giant petrels, genus Macronectes, which are convergent with the albatrosses in size, though not behaviour
- * The true fulmars, genus Fulmarus
- * Antarctic petrel Thalassoica antarctica
- * Cape petrel Daption capense
- * Snow petrel Pagodroma nivea
- The prions: A specialised group of a few very numerous species, all southern. They have a small, fulmar-like form and mostly filter-feed on zooplankton.
- * Pachyptila, the prions proper
- The procellariine petrels, larger or mid-sized species feeding on fish and molluscs which are fairly close to the prions:
- * Procellaria
- * Bulweria
- Shearwaters: There are numerous species in several genera with a medium number of species.
- * Calonectris
- * Puffinus, which is two rather distinct groups of larger and smaller species
- * Pseudobulweria
- * Kerguelen petrel Lugensa brevirostris
- The gadfly petrels: These are a considerable number of agile short-billed petrels in the genus Pterodroma which include the endangered Bermuda petrel and a considerable number of forms rendered extinct by human activity.
- The diving petrels: These are the four species of superficially auk-like small petrels of the southern oceans in the genus Pelacanoides.
The family Oceanitidae is the austral 'storm petrels'. They are small pelagic petrels with a fluttering flight which often follow ships. They show marked convergence with the northern Hydrobatidae in size and behaviour, but are actually more closely related to albatrosses than they are to the other petrels.