Storm-petrel

Taxobox
name = Storm-petrels

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image_width = 250px
image_caption = Wilson's Storm Petrel
regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Procellariiformes
familia = Hydrobatidae
familia_authority = Mathews, 1912
subdivision_ranks = Genera
subdivision =
*Subfamily Oceanitinae
**"Oceanites"
**"Garrodia"
**"Pelagodroma"
**"Fregetta"
**"Nesofregetta"
*Subfamily Hydrobatinae
**"Hydrobates"
**"Oceanodroma"

The storm-petrels are seabirds in the family Hydrobatidae, part of the order Procellariiformes. These smallest of seabirds feed on planktonic crustaceans and small fish picked from the surface, typically while hovering. The flight is fluttering and sometimes bat-like.

Storm-petrels have a cosmopolitan distribution, being found in all oceans. They are strictly pelagic, coming to land only when breeding. In the case of most species, little is known of their behaviour and distribution at sea, where they can be hard to find and harder to identify. They are colonial nesters, displaying strong philopatry to their natal colonies and nesting sites. Most species nest in crevices or burrows and all but one species attends the breeding colonies nocturnally. Pairs for long term monogamous bonds and share incubation and chick feeding duties. Like many species of seabird nesting is highly protracted with incubation taking up to 50 days and fledging another 70 days after that.

Several species of storm-petrel are threatened by human activities. One species, the Guadalupe Storm-petrel, is thought to have gone extinct; the New Zealand Storm-petrel was presumed extinct until rediscovered in 2003. The principal threats to storm-petrels are introduced species, particularly mammals, in their breeding colonies; many storm-petrels habitually nest on isolated mammal free islands and are unable to cope with predators like rats and feral cats.

Taxonomy

Traditionally, two subfamilies are recognized.Carboneras, C. (1992) "Family Hydrobatidae (Storm-petrels)" P.p 258-265 in "Handbook of Birds of the World" Vol 1. Barcelona:Lynx Edicions, ISBN 84-87334-10-5] The Oceanitinae are mostly found in southern waters (though the Wilson's Storm-petrel regularly migrates into the northern hemisphere); there are 7 species in 5 genera. The Hydrobatinae are the two genera "Hydrobates" and "Oceanodroma". They are largely restricted to the northern hemisphere, although a few can visit or breed a short distance beyond the equator.

Cytochrome "b" DNA sequence analysis suggests that the family is paraphyletic and may be more accurately treated as distinct families. [Nunn, G & Stanley, S. (1998) "Body Size Effects and Rates of Cytochrome b Evolution in Tube-Nosed Seabirds" "Molecular Biology and Evolution" 15(10): 1360-1371 [http://mbe.oxfordjournals.org/cgi/reprint/15/10/1360.pdf] [http://mbe.oxfordjournals.org/cgi/reprint/17/11/1774.pdf Corrigendum] ] The same study found that the storm-petrels are certainly ancestral to the Procellariiformes. The first split was the subfamily Hydrobatinae, with the Oceanitinae splitting from the rest of the order at a later date. Few fossil species have been found, with the earliest being from the Upper Miocene.

Morphology and flight

Storm-petrels are the smallest of all the seabirds, ranging in size from 13-26 cm in length. There are two body shapes in the family; the Oceanitinae have short wings, square tails, elongated skulls, and long legs; the Hydrobatinae have longer wings, forked or wedge-shaped tails and shorter legs. The legs of all storm-petrels are proportionally longer than those of other Procellariiformes, but they are very weak and unable to support the bird's weight for more than a few steps.

The plumage of the Oceanitinae is dark with white underparts (with the exception of the Wilson's Storm-petrel) All but two of the Hydrobatinae are mostly dark in colour with varying amounts of white on the rump. Two species have different plumage entirely, the Hornby's Storm-petrel which has white undersides and facial markings, and the Fork-tailed Storm-petrel which has pale grey plumage. [Harrison, P. (1983) "Seabirds, an identification guide" Houghton Mifflin Company:Boston ISBN 0-395-33253-2] This is a notoriously difficult group to identify at sea. Onley and Scofield (2007) state that much published information is incorrect, and that photographs in the major seabird books and websites are frequently incorrectly ascribed as to species. They also consider that several national bird lists include species which have been incorrectly identified or have been accepted on inadequate evidence. [ Onley and Scofield, (2007) "Albatrosses, Petrels and Shearwaters of the World". Helm ISBN 978-0-7136-4332-9]

Storm-petrels use a variety of techniques to aid flight. Most species will occasionally feed by surface pattering, holding and moving their feet on the water's surface while holding steady above the water. They remain stationary by hovering with rapid fluttering or by using the wind to anchor themselves in place.Withers, P.C (1979) "Aerodynamics and Hydrodynamics of the ‘Hovering’ Flight of Wilson's Storm Petrel" "Journal of Experimental Biology" 80: 83-91 [http://jeb.biologists.org/cgi/reprint/80/1/83] ] This method of feeding flight is most commonly used by Oceanitinae storm-petrels. 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. [Erickson, J. (1955) "Flight behavior of the Procellariiformes" "The Auk" 72: 415-420 [http://elibrary.unm.edu/sora/Auk/v072n04/p0415-p0420.pdf#search=%22White-faced%20Storm-petrel%20locomotion%22] ] Storm-petrels also use dynamic soaring and slope soaring to travel over the ocean surface. Dynamic soaring is used mostly by the Hydrobatinae, gliding across wave fronts gaining energy from the vertical wind gradient. [Pennycuick, C. J. (1982). "The flight of petrels and albatrosses (Procellariiformes), observed in South Georgia and its vicinity". "Philosophical Transactions of the Royal Society of London B" 300: 75–106.] [Brinkley, E. & Humann, A. (2001) "Storm-petrels" in "The Sibley Guide to Bird Life and Behaviour" (Elphick, C., Dunning J. & Sibley D. "eds") Alfred A. Knopf:New York ISBN 0-679-45123-4] Slope soaring is more straightforward and favoured by the Oceanitinae, the storm-petrel turns to the wind, gaining height, from where it can then glide back down to the sea.

Diet

The diet of may storm-petrels species is poorly known due to difficulties in researching; overall the family is though to concentrate on crustaceans.Brooke, M. (2004). "Albatrosses And Petrels Across The World" Oxford University Press, Oxford, UK ISBN 0-19-850125-0] Small fish, oil droplets and molluscs are also taken by many species. Some species are known to be rather more specialised; the Grey-backed Storm-petrel is known to concentrate on the larvae of goose barnacles.

Almost all species forage in the pelagic zone, except for the White-vented Storm-petrels which are coastal feeders in the Galapagos Islands. Although storm-petrels are capable of swimming well and often form rafts on the water's surface they do not feed on the water. Instead feeding usually takes place on the wing, with birds hovering above or 'walking' on the surface (see morphology) and snatching small morsels. Rarely prey is obtained by making shallow dives under the surface.

Like many seabirds storm-petrels will associate with other species of seabird and marine mammal species in order to help obtain food. It is theorised that they benefit from the actions of diving predators such as seals and penguins which push prey up towards the surface while hunting allowing the surface feeding storm-petrels to reach them. [Harrison N., Whitehouse M., Heinemann D., Prince P., Hunt G., Veit R. (1991) "Observations of Multispecies Seabird Flocks around South Georgia" "Auk" 108(4): 801-810 [http://elibrary.unm.edu/sora/Auk/v108n04/p0801-p0810.pdf] ]

Distribution and movements

Storm-petrels are found in all the world's oceans and in most of its seas. They are absent as breeders from the western Indian Ocean and as regular migrants or residents from the far north of the Arctic Ocean as well as the eastern extents of the Mediterranean, the Black Sea and areas of brackish water. The Oceanitinae are typically found in the southern hemisphere and the Hydrobatinae in the northern hemisphere.

Several species of storm-petrel undertake migrations after the breeding season. The most widely travelled migrant is the Wilson's Storm-petrel which after breeding in Antarctica and the subantarctic islands regularly crosses the equator to the waters of the north Pacific and Atlantic. Other species undertake migrations of differing lengths; long ones, such as the Swinhoe's Storm-petrel, which breeds in the west Pacific and migrates to the west Indian Ocean; [ Van Den Berg AB, Smeenk C, Bosman CAW, Haase BJM, Van Der Niet AM, Cadée GC (1990) "Barau’s petrel "Pterodroma baraui", Jouanin’s petrel "Bulweria fallax" and other seabirds in the northern Indian Ocean in June–July 1984 and 1985." "Ardea" 79:1–14 ] and other seabirds in the or shorter ones, such as the Black Storm-petrel which nests in southern California and migrates down the coast of Central America as far south as Colombia. [Ainley, D. G., and W. T. Everett. 2001. Black Storm-Petrel ("Oceanodroma melania"). In "The Birds of North America", No. 577 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.] Some species, like the Tristram's Storm-petrel or the Grey-backed Storm-petrel are thought to be essentially sedentary and not undertake any migrations away from their breeding islands.

Breeding

Storm-petrels nest colonially, for the most part on islands; although a few species breed on the mainland, particularly Antarctica. Nesting sites are attended nocturnally in order to avoid predators; [Bretagnolle, V. (1990) "Effect of moon on activity of petrels (Class Aves) from the Selvagen Islands (Portugal)" "Canadian Journal of Zoology" 68: 1404-1409] although the Wedge-rumped Storm-petrels nesting in the Galapagos Islands are the exception to this rule and attend their nesting sites during the day. [Ayala L & Sanchez-Scaglioni R (2007) "A new breeding location for Wedge-rumped Storm-Petrels ("Oceanodroma tethys kelsalli") in Peru" "Journal of Field Ornithology" 78(3): 303-307 doi:10.1111/j.1557-9263.2007.00106.x] Storm-petrels display high levels of philopatry, returning to their natal colonies to breed. In one instance a Band-rumped Storm-petrel was caught as an adult 2m from its natal burrow. [Harris, M. (1979) "Survival and ages of first breeding of Galapagos seabirds" "Bird Banding" 50(1): 56-61 [http://elibrary.unm.edu/sora/JFO/v050n01/p0056-p0061.pdf] ] Storm-petrels nest either in burrows dug into soil or sand, or in small crevices in rocks and scree. Competition for nesting sites is intense in colonies where storm-petrels compete with other burrowing petrels, with shearwaters having been recorded killing storm-petrels in order to occupy their burrows. [Ramos, J.A., Monteiro, L.R., Sola, E., Moniz, Z., (1997). "Characteristics and competition of nest cavities in burrowing Procellariiformes" "Condor" 99: 634–641. [http://elibrary.unm.edu/sora/Condor/files/issues/v099n03/p0634-p0641.pdf#search=%22CHARACTERISTICS%20AND%20COMPETITION%20FOR%20NEST%20CAVITIES%20IN%22] ] Colonies can be extremely large and dense; 840,000 pairs of White-faced Storm Petrel nest on South East Island in the Chatham Islands in burrow densities of between 1.18 - 0.47 burrows/m²; densities as high as 8 pairs/m² for Madeiran Storm-petrels in the Galapagos and colonies 3.6 million strong for Leach's Storm Petrel have been recorded. [West, J. & Nilsson, R. (1994) "Habitat use and burrow densities of burrow-nesting seabirds on South East Island, Chatham Islands, New Zealand" "Notornis (Supplement)" 41 27-37 [http://www.notornis.org.nz/free_issues/Notornis_41-1994/Notornis_41_sup_27.pdf#search=%22storm-petrel%22] ]

Storm-petrels are monogamous and form long-term pair bonds that last a number of years. Studies of paternity using DNA fingerprinting have shown that, unlike many other monogamous birds, infidelity (extra-pair matings) is very rare. [Mauwk, T., Waite, T. & Parker, P. (1995) "Monogamy in Leach's Storm Petrel:DNA-fingerprinting evidence" "Auk" 112(2): 473-482 [http://scholar.google.com/url?sa=U&q=http://elibrary.unm.edu/sora/Auk/v112n02/p0473-p0482.pdf] ] As with the other Procellariiformes, a single egg is laid by a pair in a breeding season; if the egg fails, then usually no attempt is made to relay (although it happens rarely). Both sexes incubate in shifts of up to six days. The egg hatches after 40 or 50 days; the young is brooded continuously for another 7 days or so before being left alone in the nest during the day and fed by regurgitation at night. Meals fed to the chick weigh around 10-20% of the parent's body weight, and consist of both prey items and stomach oil. Stomach oil is an energy rich (its calorific value is around 9600 calories per gram) oil created by partly digested prey in a part of the foregut known as the proventriculus. [Warham, J. (1976) "The Incidence, Function and ecological significance of petrel stomach oils." "Proceedings of the New Zealand Ecological Society" 24 84-93 [http://www.nzes.org.nz/nzje/free_issues/ProNZES24_84.pdf] ] By partly converting prey items into stomach oil storm-petrels can maximise the amount of energy chicks receive during feed, an advantage for small seabirds that can only make a single visit to the chick during a 24 hour period (at night). [Obst, B & Nagy, K (1993) "Stomach Oil and the Energy Budget of Wilson's Storm-Petrel Nestlings" "Condor" 95: 792-805 [http://elibrary.unm.edu/sora/Condor/files/issues/v095n04/p0792-p0805.pdf#search=%22STOMACH%20OIL%20AND%20THE%20ENERGY%20BUDGET%22] ] The average age at which chicks fledge depends on the species, taking between 50 or 70 days. The time taken to hatch and raise the young is long for the bird's size but is typical of seabirds, which in general are K-selected, living much longer, delay breeding for longer, and invest more effort into fewer young.Schreiber, Elizabeth A. & Burger, Joanne.(2001.) "Biology of Marine Birds", Boca Raton:CRC Press, ISBN 0-8493-9882-7] Storm-petrels have been recorded living as long as 30 years. [Klimkiewicz, M. K. 2007. [http://www.pwrc.usgs.gov/BBL/homepage/longvrec.htm Longevity Records of North American Birds] . Version 2007.1. Patuxent Wildlife Research Center. Bird Banding Laboratory. Laurel MD.]

Relationship with humans

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thumb|The_decline_of_the_Ashy Storm-petrel has led to it being declared an endangered species.] The name "petrel" is a diminutive form of "Peter", a reference to Saint Peter; it was given to these birds because they sometimes appear to walk across the water's surface. The more specific 'storm petrel' or 'stormy petrel' is a reference to their habit of hiding in the lee of ships during storms.Slotterback, J. W. (2002). Band-rumped Storm-Petrel ("Oceanodroma castro") and Tristram’s Storm-Petrel ("Oceanodroma tristrami"). In "The Birds of North America", No. 673 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.] Early sailors named these birds "Mother Carey's Chickens" because they were thought to warn of oncoming storms; this name is based on a corrupted form of "Mater Cara", a name for the Blessed Virgin Mary.

Threats and conservation

Several species of storm-petrel are threatened by human activities. [IUCN, 2006. [http://www.iucnredlist.org/search/search.php?freetext=Hydrobatidae&modifier=phrase&criteria=wholedb&taxa_species=1&Submit.x=87&Submit.y=11&redlistCategory%5B%5D=allex&redlistAssessyear%5B%5D=all&country%5B%5D=all&aquatic%5B%5D=all&regions%5B%5D=all&habitats%5B%5D=all&threats%5B%5D=all Red List: Storm-petrel Species] Retrieved August 27, 2006.] Two, the Guadalupe Storm-petrel, and the New Zealand Storm-petrel, are listed as critically endangered. The Guadalupe Storm-petrel has not been observed since 1906 and most authorities consider it extinct. The New Zealand Storm-petrel was also considered extinct for many years but was sighted again in 2003, though the population is likely to be very small. One species (the Ashy Storm-petrel) is listed as endangered due to a 42% decline over twenty years, [Sydeman, W., Nurr, N., McLaren, E. & McChesney G. (1998). "Status and Trends of the Ashy Storm-Petrel on Southeast Farallon Island, California, based upon capture-recapture analyses" "Condor" 100: 438-447 ] and two other species are also listed as near threatened or worse. In addition four species are so poorly known that they are listed as data deficient. For two species, the recently rediscovered New Zealand Storm-petrel and the Ringed Storm-petrel, even the sites of their breeding colonies remain a mystery.

Storm-petrels face the same threats as other seabirds, in particular they are threatened by introduced species. The Guadalupe Storm-petrel was driven to extinction by feral cats, [A contemporary account of the decline of the Guadalupe Storm-petrel can be found here - Thayer, J. & Bangs, O (1908) "The Present State of the Ornis of Guadaloupe Island" "Condor" 10(3): 101-106 [http://elibrary.unm.edu/sora/Condor/files/issues/v010n03/p0101-p0106.pdf#search=%22The%20Present%20State%20of%20the%20Ornis%20of%20Guadaloupe%20Island%20%22] ] and introduced predators such as have also been responsible for declines in other species. Habitat degradation which limits nesting opportunities caused by introduced goats and pigs is also a problem, especially if it increases competition from more aggressive burrowing petrels.

pecies

References

External links

* [http://ibc.hbw.com/ibc/phtml/familia.phtml?idFamilia=12 Storm-petrel videos] on the Internet Bird Collection