Diving-petrel

(Pelecanoididae)

Class: Aves

Order: Procellariiformes

Family: Pelecanoididae

Thumbnail description
Small-sized, black-and-white colored, stocky, short-winged, tube-nosed seabirds with nostrils pointing upwards. Diving-petrels dive and swim for their food

Size
7–10 in (18–25 cm); 4–8 oz (120–220 g)

Number of genera, species
1 genus; 4 species

Habitat
Cool and cold oceans

Conservation status
One species is Endangered

Distribution
Occurs in cool and cold oceans of the Southern Hemisphere, usually close to breeding sites

Evolution and systematics

Diving-petrels (family Pelecanoididae) are in a group of seabirds known as tubenoses (order Procellariiformes), all of which have a distinctive pair of tube-like, salt-excreting, external nostrils on the top or sides of the upper mandible. Other families in this group are the albatrosses (Diomedeidae), storm-petrels (Oceanitidae), and fulmars, petrels, shear-waters, and prions (Procellariidae).

With their rapid wing beats and stocky, short-necked appearance, diving-petrels resemble the little auks of the Northern Hemisphere (family Alcidae). This resemblance represents an example of convergent evolution between unrelated species occupying similar ecological niches in widely separated parts of the world.

Physical characteristics

Diving-petrels are small, stocky-bodied, short-winged, tube-nosed seabirds that dive and swim to catch their food. Their body length is 7–10 in (18–25 cm) and they weigh 4–8 oz (120–220 g). Their bill is small, short, broad, and slightly hooked at the tip. The nostril tubes on the upper bill are parallel, short, have a thin partition between them, and are directed upward. Diving-petrels are the only tubenoses in which the nostrils project upward rather than forward, which may be an adaptation to diving. The wings are relatively short and wide and the flight is consequently swift, direct, fluttering, and whirring. When diving and swimming, the wings are used as flippers to achieve forward propulsion. The plumage is gray, blue-gray, or black on top and whitish on the underside. The primary feathers all molt simultaneously, rendering the birds temporarily flightless.

Distribution

Diving-petrels are restricted to waters of the Southern Hemisphere, generally between latitudes 35° south and 60° south. They usually occur in coastal waters but may sometimes be found well offshore.

Peruvian and Magellan diving-petrels (Pelecanoides garnotii and P. magellani) inhabit South American waters. Common and South Georgian diving-petrels (P. urinatrix and P. georgicus) are circumpolar species.

Habitat

Diving-petrels breed on remote oceanic islands. They feed in cool and cold oceans, usually rather close to their breeding sites.

Behavior

Diving-petrels characteristically fly low, direct, and fast over water, occasionally diving and swimming to catch their prey. In rough weather, they may fly right through the crests of waves rather than around or over them. Diving-petrels are the only tubenoses that swim underwater using their wings for propulsion. Diving-petrels only come to land to breed, and they will do so only at night. This wariness is an adaptive response to predation by larger seabirds, such as skuas. Diving-petrels are not migratory, but they may wander during the nonbreeding season.

Feeding ecology and diet

Diving-petrels catch their prey of small fishes and crustaceans by flying directly into the water and then using their wings to swim underwater to pursue their food. They emerge from the water in a similar manner, by flying directly out into the air. Diving-petrels usually feed in flocks.

Reproductive biology

Diving-petrels breed in colonies. They nest in burrows excavated in organic turf and also in cavities among rocks and tufts of grass. Each female lays only one relatively large white egg that weighs 10–15% of the female's body weight. The incubation period is about eight weeks, and both parents tend the egg during one-day-long watches. Egg laying generally occurs between July and December. The newly hatched chick is brooded closely for its first two weeks of life. After about eight weeks the chick fledges and begins to fend for itself. After the breeding season ends, adults molt all flight feathers and are flightless until this plumage has regrown. Diving-petrels reach sexual maturity in two or three years, which is considerably faster than other tubenoses.

Conservation status

The Peruvian diving-petrel is listed as Endangered. This rare species has an extremely small breeding range on only four islands off the west coast of South America, and all of its subpopulations are declining, some quite rapidly. The declines in abundance have been caused by excessive hunting of these birds for food, disturbance of their habitat during guano collection, predation on eggs, nestlings, and adults by introduced mammals, and diminishment of their food supply by commercial overfishing of the waters around their breeding colonies.

Significance to humans

Diving-petrels are not of much importance to humans, except for the economic benefits of marine ecotourism related to birdwatching.

Species accounts

Resources

BirdLife International. Threatened Birds of the World. Barcelona: Lynx Edicions and BirdLife International, 2000.

Carboneras, C. "Family Pelecanoididae (Diving-petrels)." Handbook of the Birds of the World. Vol. 1, edited by J. del Hoyo, A. Elliott, and J. Sargatal. Barcelona: Lynx Edicions, 1992.

Harrison, P. Seabirds. An Identification Guide. Beckenham, U.K.: Croom Helm Ltd., 1983.

Warham, J. The Behaviour, Population Biology and Physiology of the Petrels. San Diego: Academic Press, 1996.

BirdLife International. Wellbrook Court, Girton Road, Cambridge, Cambridgeshire CB3 0NA United Kingdom. Phone: +44 1 223 277 318. Fax: +44-1-223-277-200. E-mail: birdlife@birdlife.org.uk Web site:

IUCN–The World Conservation Union. Rue Mauverney 28, Gland, 1196 Switzerland. Phone: +41-22-999-0001. Fax: +41-22-999-0025. E-mail: mail@hq.iucn.org Web site:

[Article by: Bill Freedman, PhD]

The noun has one meaning:

Meaning #1: any of several small diving birds of S hemisphere seas; somewhat resemble auks

Diving-petrel
Peruvian Diving-petrel, Pelecanoides garnotii
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Procellariiformes
Family:	Pelecanoididae G.R. Gray, 1871
Genus:	Pelecanoides Lacépède, 1799
Species
Pelecanoides garnotii Pelecanoides magellani Pelecanoides georgicus Pelecanoides urinatrix

The diving-petrels are seabirds in the bird order Procellariiformes. There are four very similar species all in the family Pelecanoididae and genus Pelecanoides Lacépède, 1799, distinguished only by small differences in the coloration of their plumage and their bill construction.

Diving-petrels are auk-like small petrels of the southern oceans. The resemblances with the auks are due to convergent evolution, since both families feed by pursuit diving, although some researchers have in the past suggested that the similarities are due to relatedness. Amongst the Procellariiformes the diving petrels are the family most adapted to life in the sea rather than flying over it, and are generally found closer inshore than other families in the order.

Diving-petrels are plankton feeders, taking mostly crustacean prey such as krill, copepods and the amphipod Themisto gaudichaudii, also taking small fish and squid. They have several adaptations for obtaining their prey including short powerful wings, a gular pouch for storing food, and their nostrils open upwards rather than forward pointing as it is in other tubenoses.

Contents 1 Description and morphology 2 Breeding 3 Status and conservation 4 Systematics and evolution 5 Footnotes 6 References

Description and morphology

The diving-petrels are small petrels that measure between 19-23 cm (7.5-9 in) and weigh between 120-200 g (4-7 oz). They are highly uniform in appearance, and very difficult to separate when seen at sea. They are best separated by the size and shape of their short bills. The plumage is shining black on the top and white on the underside. Their wings are short, particularly with regards to overall body size, and used in a highly characteristic whirring flight. This flight is low over the water and diving petrels will fly through the crests of waves without any interruption of their flight path. In the water these wings are half folded and used as paddles to propel the bird after its prey.

Breeding

These birds nest in colonies on islands. One white egg is laid in a burrow in turf or soft soil that's usually covered with vegetation, feathers, or small rocks. They are nocturnal at the breeding colonies. It has a long period of parental care (around 45 - 60 days) in the burrow, but once the chick fledges out to sea it is on its own.

Status and conservation

Of the four species two, the Peruvian Diving-petrel and the Magellan Diving-petrel, have highly restricted ranges around South America's coasts, whilst the Common Diving-petrel and the South Georgia Diving-petrel range widely across the southern oceans, breeding on islands off New Zealand, sub-Antarctic islands in the Indian Ocean, and islands in the south Atlantic (like Tristan da Cunha).

Diving-petrels are amongst the world's most numerous birds, with Common and South Georgia Diving-petrels numbering several million pairs each. The Peruvian Diving-petrel, on the other hand, is threatened by guano extraction, introduced species and climate change, and is listed as an endangered species.

Systematics and evolution

Some studies published on the phylogeny of the petrels suggests that the diving-petrels are actually members of the family Procellariidae, and some taxonomic works treat them as such.^[1]

The four species are:

• Peruvian Diving-petrel Pelecanoides garnotii
• Magellan Diving-petrel Pelecanoides magellani
• South Georgia Diving-petrel Pelecanoides georgicus
• Common Diving-petrel Pelecanoides urinatrix

The evolution and systematics of these birds is not well researched. Several populations were described as distinct species and while most of them are only subspecies, some may indeed be distinct. The prehistoric fossil record was long limited to very fragmentary remains described as P. cymatotrypetes found in Early Pliocene deposits of Langebaanweg, South Africa; while this bird apparently was close to the Common Diving-petrel, no members of the genus are known from South African waters today.^[2]

In 2007, a humerus piece from New Zealand was described as P. miokuaka. This was found in Early/Middle Miocene deposits and just as may be expected, it far more resembles diving-petrels than any other known bird, but presents a less apomorphic condition.^[3]

Footnotes

1. ^ Christidis, Les; Boles, Walter (2008). Systematics and taxonomy of Australian Birds. Collingwood, Vic: CSIRO Publishing. pp. 81-82. ISBN 9780643065116. 
2. ^ Olson (1985)
3. ^ Worthy, Trevor; Tennyson, Alan J. D.; Jones, C.; McNamara, James A.; Douglas, Barry J. (2007). "Miocene waterfowl and other birds from central Otago, New Zealand". Journal of Systematic Palaeontology 5 (1): 1-39. doi:10.1017/S1477201906001957. ISSN 1477-2019. 

References

• Olson, Storrs L. (1985): Section X.H.3. Pelecanoididae. In: Farner, D.S.; King, J.R. & Parkes, Kenneth C. (eds.): Avian Biology 8: 79-238. Academic Press, New York.

v • d • e Order: Procellariiformes Family Diomedeidae (Albatrosses) • Procellariidae (Shearwaters and petrels) • Hydrobatidae (Storm-petrels) • Pelecanoididae (Diving-petrels) • †Diomedeoididae (Diomedeoidids) Related subjects List of Procellariidae • Stomach oil  • Agreement on the Conservation of Albatrosses and Petrels

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