Procellariiformes is an order of seabirds that comprises four families; the albatrosses, the petrels and shearwaters, and two families of storm petrels. Formerly called Tubinares and still called tubenoses in English, Procellariiformes are often referred to collectively as the petrels, a term that has been applied to all members of the order,Warham, J. (1996). The Behaviour, Population, Biology and Physiology of the Petrels. London: Academic Press, or more commonly all the families except the albatrosses.Brooke, 2004. They are almost exclusively pelagic (feeding in the open ocean), and have a cosmopolitan distribution across the world's oceans, with the highest diversity being the seas around New Zealand.
Procellariiformes are colonial, mostly nesting on remote, predator-free islands. The larger species nest on the surface, while most smaller species nest in natural cavities and burrows. They exhibit strong philopatry, returning to their natal colony to breed and returning to the same nesting site over many years. Procellariiforms are monogamous and form long-term pair bonds that are formed over several years and may last for the life of the pair. A single egg is laid per nesting attempt, and usually a single nesting attempt is made per year, although the larger albatrosses may only nest once every two years. Both parents participate in incubation and chick rearing. Incubation times are long compared to other birds, as are fledging periods. Once a chick has fledged there is no further parental care. Birds of this order generally have long lifespans spanning multiple decades; the world's oldest known bird, Wisdom, is now around 75 years old.
Procellariiformes have had a long relationship with humans, with the albatrosses in particular have been the subject of numerous cultural depictions. They have been important food sources for many people, and continue to be hunted as such in some parts of the world. Procellariiforms include some of the most endangered bird taxa, with many species threatened with extinction due to introduced predators in their breeding colonies, marine pollution and the danger of fisheries by-catch. Scientists, conservationists, fishermen, and governments around the world are working to reduce the threats posed to them, and these efforts have led to the signing of the Agreement on the Conservation of Albatrosses and Petrels, a legally binding international treaty signed in 2001.
Nomenclature
The name "tubenoses", which may be used to refer to all members of this clade, refers to the "naricorns" or bony nostrils that distinguish these birds from other groups.
The word petrel (first recorded in that spelling 1602) comes from likely earlier (though not recorded until 1676) 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 (Matthew xiv.28), being formed in English as a diminutive of Peter (< Old (?) < Late < Late < < = "stone"); this connection is however due to later speculation.
Taxonomy
The order Procellariiformes was named by German anatomist Max Fürbringer in 1888. The word comes from the Latin word procella, which means a violent wind or a storm, and -iformes for order. Until the beginning of the 20th century, the family Hydrobatidae was named Procellariidae, and the family now called Procellariidae was rendered "Puffinidae". The order itself was called Tubinares. A major early work on this group is Frederick DuCane Godman's Monograph of the Petrels, five fascicles, 1907–1910, with figures by John Gerrard Keulemans.
Phylogenetic studies based on genetics have repeatedly proven this order to be a natural grouping, being monophyletic. In the Sibley-Ahlquist taxonomy, the tubenoses were included in a greatly enlarged order "Ciconiiformes". This taxonomic treatment was almost certainly erroneous, but its assumption of a close evolutionary relationship with other "higher waterbirds" – such as loons (Gaviiformes) and penguins (Sphenisciformes) – appears to be correct. The procellariiforms are most closely related to penguins, having diverged from them about 60 million years ago.
The diving petrels in the genus Pelecanoides were formerly placed in their own family Pelecanoididae. When genetic studies found that they were embedded within the family Procellariidae, the two families were merged.
All the storm petrels were once placed in the family Hydrobatidae but genetic data indicated that Hydrobatidae consisted of two deeply divergent clades that were not sister taxa. In 2018 the austral storm petrels were moved to the new family Oceanitidae. The northern storm petrels in the family Hydrobatidae are more closely related to the family Procellariidae than they are to the austral storm petrels in the family Oceanitidae.
Earlier molecular phylogenetic studies found the family Oceantidae containing the austral storm petrels as the most basal with differing branching topologies for other three families. More recent large-scale studies have found a consistent pattern with the albatross family Diomedeidae as the most basal and Hydrobatidae sister to Procellariidae.
There are 147 living species of procellariiform worldwide, and the order is divided into four extant families, with a fifth prehistorically extinct:
Family Diomedeidae (albatrosses) are very large seabirds with a large strong hooked bill. They have strong legs, enabling them to walk well on land.Tickell, W.L.N. (2000). Albatrosses. Pica Press. Family Oceanitidae (Austral storm petrels) are among the smallest seabirds, with fluttering flight and long but weak legs. Most have dark upperparts and a white underside. Family Hydrobatidae (northern storm petrels) are similar to the austral storm petrels but have longer more pointed wings and most species have forked tails. Family Procellariidae (shearwaters, fulmarine petrels, gadfly petrels, and prions) are a varied group of small or medium-sized seabirds, the largest being the giant petrels. They are heavy for their size, with a high wing loading, so they need to fly fast. Most, except the giant petrels, have weak legs and are nearly helpless on land. Family †Diomedeoididae (Early Oligocene – Early Miocene) is an extinct group that had narrow beaks and feet with wide, flat phalanges, especially on the fourth toe.
Fossils of a bird similar to a petrel from the Eocene have been found in the London Clay and in Louisiana. Diving petrels occurred in the Miocene, with a species from that family (Pelecanoides miokuaka) being described in 2007. The most numerous fossils from the Paleogene are those from the extinct family Diomedeoididae, fossils of which have been found in Central Europe and Iran.
Description
Procellariiforms range in size from the very large wandering albatross, at and a wingspan, to tiny birds like the least storm petrel, at with a wingspan, and the smallest of the prions, the fairy prion, with a wingspan of . Their nostrils are enclosed in one or two tubes on their straight deeply-grooved bills with hooked tips. The beaks are made up of several plates. Their wings are long and narrow; the feet are webbed, and the hind toe is undeveloped or non-existent; their adult plumage is predominantly monochromatic, being black, white, and/or grey.
The order has a few unifying characteristics, starting with their tubular nasal passage which is used for olfaction. Procellariiformes that nest in burrows have a strong sense of smell, being able to detect dimethyl sulfide released from plankton in the ocean. This ability to smell helps to locate patchily distributed prey at sea and may also help locate their nests within nesting colonies. In contrast, surface nesting Procellariiformes have increased vision, having six times better spatial resolution than those that nest in burrows. The structure of the bill, which contains seven to nine distinct horny plates, is another unifying feature, although there are differences within the order. Petrels have a plate called the maxillary unguis that forms a hook on the maxilla. The smaller members of the order have a comb-like mandible, made by the tomial plate, for plankton feeding. Most members of the order are unable to walk well on land, and many species visit their remote breeding islands only at night. The exceptions are the huge albatrosses, several of the gadfly petrels and shearwaters and the fulmars. The latter can disable even large predatory birds with their obnoxious stomach oil, which they can project some distance. This stomach oil, stored in the proventriculus, is a digestive residue created in the foregut of all tubenoses except the diving petrels, and is used mainly for storage of energy-rich food during their long flights. The oil is also fed to their young, as well as being used for defence.
Procellariiforms drink seawater, so they have to excrete excess salt. All birds have an enlarged nasal gland at the base of the bill, above the eyes, and in the Procellariiformes the gland is active. In general terms, the salt gland removes salt from the system and forms a 5 percent saline solution that drips out of the nostrils, or is forcibly ejected in some petrels. The processes behind this involve high levels of sodium ion reabsorption into the blood plasma within the kidneys, and secretion of sodium chloride via the salt glands using less water than was absorbed, which essentially generates salt-free water for other physiological uses. This high efficiency of sodium ion absorption is attributed to mammalian-type nephrons.
Behaviour and biology
Most albatrosses and procellariids use two techniques to minimise exertion while flying, dynamic soaring, and slope soaring. The albatrosses and giant petrels share a morphological adaptation to aid in flight, a sheet of tendon which locks the wing when fully extended, allowing the wing to be kept up and out without any muscle effort. Amongst the Oceanitidae storm petrels there are two unique flight patterns, one being surface pattering. In this they move across the water surface holding and moving their feet on the water's surface while holding steady above the water, and remaining stationary by hovering with rapid fluttering or by using the wind to anchor themselves in place. A similar flight method is thought to have been used by the extinct petrel family Diomedeoididae. The white-faced storm petrel possesses a unique variation on pattering, holding its wings motionless and at an angle into the wind, it pushes itself off the water's surface in a succession of bounding jumps.
Distribution and movements
The procellariiforms have a cosmopolitan distribution across the world's oceans and seas, although at the levels of family and genus there are some clear patterns. Antarctic petrels, Thalassoica antarctica, have to fly over to get to the ocean from their breeding colonies in Antarctica, and northern fulmars breed on the northeastern tip of Greenland, the northernmost piece of land. The most cosmopolitan family is the Procellariidae, which are found in tropical, temperate and polar zones of both the Northern and the Southern Hemispheres, though the majority do not breed in the tropics, and half the species are restricted to southern temperate and polar regions. The gadfly petrels, Pterodroma, have a generally tropical and temperate distribution, whereas the fulmarine petrels are mostly polar with some temperate species. The majority of the fulmarine petrels, along with all of the prions, are confined to the Southern Hemisphere.