Everything about Procellariiformes totally explained
Procellariiformes is an order of
seabirds that's comprised of four
families, the
albatrosses,
procellariids,
storm-petrels and
diving petrels. Formerly called
Tubinares and still called
tubenoses in English, they're often referred to collectively as the
petrels, a term that has been applied to all Procellariiformes or more commonly all the families except the albatrosses. They are almost exclusively
pelagic (feeding in the open ocean). They have a
cosmopolitan distribution across the world's oceans, with the highest diversity being 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 exibit strong
philopatry, returning to their natal colony to breed and returning to the same nesting site over many years. Procellariiformes are
monogamous and form long term pair bonds which are formed over several years and may last for the life of the pair. Only a single
egg is laid per nesting attempt, and usually only a single nesting attempt is made per year, although in 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 fledgling periods. Once a chick has fledged there's no further parental care.
Procellariiformes have had a long relationship with humans. They have been important food sources for many people, and continue to be hunted as such in some parts of the world. They have also been the subject of numerous cultural depictions, particularly albatrosses. Procellariiformes are one 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.
Biology
Distribution and movements
The Procellariiformes have a
cosmopolitan distribution across the world's oceans and seas, although at the levels of family and genus there are some clear patterns. The most cosmopolitan family is the
Procellariidae, although within that family there are some gaps in distribution. 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 the
prions, are confined to the southern hemisphere. The
shearwaters have the most widespread distribution, although they're absent from the Pacific north of Japan as breeding birds.
The
storm-petrels are almost as widespread as the procellariids, and fall into two distinct subfamilies; the
Oceanitinae have a mostly southern hemisphere distribution and the
Hydrobatinae are found mostly in the northern hemisphere. Amongst the
albatrosses the majority of the family is restricted to the southern hemisphere, feeding and nesting in cool temperate areas, although one genus,
Phoebastria, ranges across the north Pacific. The family is absent from the north Atlantic, although fossil records indicate they bred there once. Finally the
diving-petrels are restricted to the southern hemisphere.
The various species within the order have a variety of
migration strategies. Some species undertake regular trans-equatorial migrations, such as the
Sooty Shearwater which annually migrates from its breeding grounds in New Zealand and Chile to the North Pacific off
Japan,
Alaska and California, an annual round trip of 64,000 km (40,000
miless), the longest measured annual migration of any bird . A number of otherpetrel species undertake trans-equatorial migrations, including the
Wilson's Storm-petrel and the
Providence Petrel, but no
albatrosses cross do due to their reliance on wind assisted flight. There are other long-distant migrants within the order;
Swinhoe's Storm-petrels breed in the western Pacific and migrates to the western Indian Ocean, and
Bonin Petrels nesting in
Hawaii migrate to the coast of Japan during the non-breeding season.
Morphology and flight
Procellariiformes range in size from the very large
Southern Royal Albatross (10k) to the tiny
Least Storm-petrel (20 g). They have their nostrils enclosed in one or two tubes on their straight, deeply grooved bills with hooked tips. The beaks are made up from several plates. Wings are long and narrow; feet are webbed, and the hind toe is undeveloped or non-existent. Plumage is predominantly black, white and grey.
The order has a characteristic tubular nasal passage which is used for
olfaction. This ability to smell helps to locate patchily distributed prey at sea and may also help locate their nests within
nesting colonies.
The longer-winged species fly using a switchback technique to minimise active flapping. All eat fish,
squid or similar marine prey.
Most 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 fulmar-petrels. The latter can disable even large predatory birds with their obnoxious
stomach oil, which they can project some distance. This stomach oil 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 as well as for defence.
Breeding behaviour
Breeding colonies
All Procellariiformes are
colonial, predominantly breeding on offshore or oceanic islands. The few species that nest on continents do so in inhospitable environments such as dry deserts or on Antarctica. These colonies can vary from the widely spaced colonies of the
giant petrels to the dense 3.6 million strong colonies of
Leach's Storm Petrels. For almost all species the need to breed is the only reason that Procellariiformes return to land at all. Within the colonies pairs defend usually small
territories (the giant petrels and some albatrosses can have very large territories) which is either the small area around the nest or a burrow. Competition between pairs can be intense, as can competition between species, particularly for burrows. Larger species of petrels will even kill the chicks and even adults of smaller species in disputes over burrows. Burrows and natural crevices are most commonly used by the smaller species; all the
storm-petrels and
diving-petrels are cavity nesters, as are many of the
procellariids. The
fulmarine petrels and some tropical
gadfly petrels and
shearwaters are surface nesters, as are all the albatrosses. Colonies are often composed of several different species of both petrels and other seabirds.
Procellariiformes show high levels of
philopatry, both site fidelity and natal philopatry. Natal philopatry is the tendency of an individual bird to return to its natal colony to breed, often many years after leaving the colony as a chick. This tendency has been shown through
ringing studies and
mitochondrial DNA studies. In the ringing studies birds ringed as chicks are recapatured close to their original nests, a tendency which can be extreme at times; in
Laysan Albatross the average distance between hatching site and the site where a bird established its own territory was 22 metres, and a study of
Cory's Shearwaters nesting near
Corsica found that of nine out of 61 male chicks that returned to breed at their natal colony actually bred in the burrow they were raised in.
Mitochondrial DNA provides evidence of restricted
gene flow between different colonies, strongly suggesting philopatry.
The other type of philopatry exhibited is site fidelity, where pairs of birds return to the same nesting site for a number of years. Among the most extreme examples known of this tendency was the fidelity of a
ringed Northern Fulmar which returned to the same site for 25 years. The average number of birds returning to the same nesting sites is high in all species studied, with figures of around 91% for
Bulwer's Petrels, and 85% of males and 76% of females for
Cory's Shearwaters (after a successful breeding attempt).
Pair bonds and life history
Procellariiformes are
monogamous breeders and form long term pair-bonds. These pair bonds take several years to develop in some species, particularly with the albatrosses. Having formed that'll last for many breeding seasons, in some cases for the life of the pair. Petrel courtship can be an elaborate affair. It reaches its extreme with the albatrosses, where pairs of albatrosses spend many years perfecting and elaborate mating dances. These dances are composed of synchronised performances of various actions such as
preening, pointing, calling, bill clacking, staring, and combinations of such behaviours (like the sky-call). Each particular pair will develop their own individual version of the dance. The breeding behaviour of other Procellariiformes are less elaborate, although similar bonding behaviours are involved, particularly for the surface nesting procellariids. These can involve synchronised flights, mutual preening and
calling. Calls are important for helping birds locate potential mates and distinguish between species and may also serve a function in helping individuals assess the quality of potential mates. After pair formation has occurred calls also serve to help them reunite, the ability of individuals to recognise their own mate has also been demonstrated in several species.
Procellariiformes are
k-selected. Breeding is delayed for several years after
fledging, sometimes for as long as eight or ten years in the case of larger species. Once they begin breeding they make only a single breeding attempt per nesting season, even if the egg is lost early on in the season that'll seldom relay. Large amounts of effort are placed into laying a single (proportionally) large
egg and raising a single chick. Procellariiformes are long-lived, the longest living albatross known survived for 51 years but was probably older, even the tiny storm-petrels are known to have survived for 30 years.
Nesting and chick rearing
The majority of Procellariiformes nest once a year and do so seasonally. Some tropical shearwaters, like the
Christmas Shearwater, are able to nest on cycles slightly shorter than a year, and the large
great albatrosses (genus
Diomedea) nest in consecutive years. Most temperate and polar species nest over the
spring-
summer, although some albatrosses and procellariids nest over the
winter. In the tropics some species breed throughout the year, but most nest in discreet periods. Procellariiformes return to the nesting colonies several months before laying, and attend their nesting sites regularly before copulation. Prior to laying females embark on a pre-laying exodus to build up reserves of energy to lay the comparably large egg.
When the female returns and lays the male takes the first
incubation stint and the female returns to sea. Incubation is shared between both sexes. The duration of individual stints varies from just a few days to several weeks, during which the incubating bird can lose a considerable amount of weight. The incubation period varies from species to species, around 40 days for the smallest storm-petrels but longer for the largest species; for albatrosses it can be as long as 70 to 80 days, which is the longest incubation period of any bird.
Upon hatching the chicks are semi-
precocial, having open eyes, a dense covering of white or grey
down feathers, and the ability to move around the nesting site. After hatching the incubating adult remains with the chick for a number of days, a period known as the guard phase. In the case of most burrow-nesting species this is only until the chick is able to
thermoregulate, usually two or three days. Diving-petrel chicks take longer to thermoregulate and have a longer guard phase than other burrow nesters. However for surface nesting species, which have to deal with a greater range of weather and also have to content with predators like
skuas and
frigatebirds, and consequently have longer guard phases, as long as two weeks in procellariids and three weeks in albatrosses.
The chick is fed by both parents. Chicks are fed on fish, squid, krill and
stomach oil. Stomach oil is
oil composed of neutral dietary
lipids that are the residue created by
digestion of the prey items. As an energy source for chicks it has several advantages over undigested prey, its
calorific value is around 9.6
kcal per gram, which is only slightly lower than the value for
diesel oil. This can be a real advantage for species that range over huge distances to provide food for hungry chicks. The oil is also used in defence. All Procellariiformes create stomach oil except the
diving-petrels.
The durations between feedings vary between species and during the stages of development. Small feeds are frequent during the guard phase, but afterwards become less frequent.
Relationship with humans
Role in culture
The most important family in terms of cultural importance is the albatrosses, which have been described by one author as "the most legendary of birds". Albatrosses have featured in poetry in the form of
Samuel Taylor Coleridge's famous poem
The Rime of the Ancient Mariner, which in turn gave rise to the usage of albatross as
metaphor for a burden. There are few instances of
petrels in culture, although there are sailors legends regarding the
storm-petrels, which are considered to to warn of oncoming storms. In general petrels were considered to be "soul birds", representing the souls of drowned sailors, and it was considered unlucky to touch them.
Exploitation
Albatrosses and petrels have been important food sources for humans for as long as people have been able to reach their remote breeding colonies. Amongst the earliest known examples of this is the remains of
shearwaters and albatrosses along with those of other seabirds in 5,000 year old
middens in
Chile, although it's likely that they were exploited prior to this. Since then many other marine cultures, both subsistence and industrial, have exploited Procellariiformes, in some cases almost to
extinction. Some cultures continue to harvest shearwaters (a practice known as
muttonbirding); for example the
Maori of
New Zealand,who use a sustainable traditional method known as
kaitiakitanga.
Threats and conservation
The albatrosses and petrels are "amongst the most severely threatened taxa worldwide". This has led to spectacular declines in some species, as Procellariiformes are slow breeders and can't replace their numbers fast enough.
Exotic species introduced to the remote breeding
colonies is also a threat to all types of Procellariiformes. These principally take the form of
predators; most albatross and petrel species are clumsy on land and are unable to defend themselves from
mammals such as
rats,
feral cats and
pigs. This phenomenon, known as
ecological naivete, has resulted in numerous declines in many species and has been strongly implicated in the
extinction of the
Guadalupe Storm-petrel. Introduced herbivores can also cause problems if they unbalance the
ecology of the island; introduced rabbits destroyed the forest understory on Cabbage Tree Island off
New South Wales; this both increased the vulnerability of the
Gould's Petrels nesting on the island to natural predators and left them vulnerable to the sticky fruits of the birdlime tree (
Pisonia umbellifera), a native plant. In the natural state these fruits lodge in the understory of the forest, but with the understory removed the fruits fall to the ground where the petrels move about, sticking to their feathers and making flight impossible.
In the past exploitation was a threat (see above), although this is less of a threat now. Other threats the ingestion of plastic
flotsam. Once swallowed, this plastic can cause a general decline in the fitness of the bird, or in some cases lodge in the gut and cause a blockage, leading to death by starvation. This can also be picked up by foraging adults and fed to chicks, stunting their development and reducing the chances of successfully fledging. Procellariids are also vulnerable to general marine pollution, as well as oil spills. Some species, such as the
Barau's Petrel and the
Newell's Shearwater, which nest high up on large developed islands are victims of light pollution. Chicks that are
fledging are attracted to streetlights and are unable to reach the sea. An estimated 20–40% of fledging Barau's Petrels are attracted to the streetlights on
Réunion.
Species
There are a total of around 125 species of Procellariiformes world-wide,
Procellariiformes are most closely related to
Sphenisciformes (Penguins).
In the
Sibley-Ahlquist taxonomy, the tubenoses are included in a greatly enlarged order
Ciconiiformes. This
taxonomic treatment is almost certainly erroneous, but the assumption of a close evolutionary relationship may be correct.
At one point (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 F. DuCane Godman's
Monograph of the Petrels, five fascicles, 1907--1910., with portraits of figures by
John Gerrard Keulemans.
Further Information
Get more info on 'Procellariiformes'.
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