Procellariidae

The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the prions, and the shearwaters. This family is part of the bird order Procellariiformes (or tubenoses), which also includes the albatrosses, the storm petrels, and the diving petrels. The procellariids are the most numerous family of tubenoses, and the most diverse. They range in size from the giant petrels, which are almost as large as the albatrosses, to the prions, which are as small as the larger storm petrels. They feed on fish, squid and crustacea, with many also taking fisheries discards and carrion. All species are accomplished long-distance foragers, and many undertake long trans-equatorial migrations. They are colonial breeders, exhibiting long-term mate fidelity and site philopatry. In all species, each pair lays a single egg per breeding season. Their incubation times and chick-rearing periods are exceptionally long compared to other birds. Many procellariids have breeding populations of over several million pairs; others number fewer than 200 birds. Humans have traditionally exploited several species of fulmar and shearwater (known as muttonbirds) for food, fuel, and bait, a practice that continues in a controlled fashion today. Several species are threatened by introduced species attacking adults and chicks in breeding colonies and by long-line fisheries. The family Procellariidae was introduced by the English zoologist William Elford Leach in a guide to the contents of the British Museum published in 1820. According to the famous DNA hybridization study into avian phylogenetic relationships by Sibley and Ahlquist, the split of the Procellariiformes into the four families occurred around 30 million years ago; a fossil bone often attributed to the order, described as the genus Tytthostonyx, has been found in rocks dating around the Cretaceous–Paleogene boundary (70-60 mya), but the remains are too incomplete for placement within the Procellariiformes to be certain.The molecular evidence suggests that the storm petrels were the first to diverge from the ancestral stock, and the albatrosses next, with the procellariids and diving petrels splitting most recently. Many taxonomists used to retain the diving petrels in this family also, but today their distinctiveness is considered well supported. However, modern procellariid genera began to appear possibly just as early as the proposed splitting of the family, with a Rupelian (Early Oligocene) fossil from Belgium tentatively attributed to the shearwater genus Puffinus,and most modern genera were established by the Miocene. Thus, a basal radiation of the Procellariiformes in the Eocene at least (as with many modern orders of birds) seems likely, especially given that significant anomalies in molecular evolution rates and patterns have been discovered in the entire family (see also Leach's storm petrel), and molecular dates must be considered extremely tentative. Some genera (Argyrodyptes, Pterodromoides) are only known from fossils. Eopuffinus from the Late Paleocene is sometimes placed in the Procellariidae, but even its placement in the Procellariiformes is quite doubtful. Sibley and Ahlquist's taxonomy has included all the members of the Procellariiformes inside the Procellariidae and that family in an enlarged Ciconiiformes, but this change has not been widely accepted. The procellariid family is usually broken up into four fairly distinct groups; the fulmarine petrels, the gadfly petrels, the prions, and the shearwaters.