Shearwaters, petrels, and fulmars

(Procellariidae)

Class Aves

Order Procellariiformes

Family Procellariidae

Thumbnail description
Medium-sized tube-nosed seabirds with hooked bill and large wingspan for gliding

Size
9.1–39 in (23–99 cm); 2.8 oz–11 lb (78 g–5 kg); wingspan 20.9–80.7 in (53–205 cm)

Number of genera, species
12 genera; 60–76 species

Habitat
Marine

Conservation status
Critically endangered: 10 species; Endangered: 6 species; Vulnerable: 20 species; Lower Risk/Near Threatened: 9 species

Distribution
Oceans worldwide

Evolution and systematics

The Procellariiformes is one of the most primitive bird orders. In his 1996 book, John Warham proposed that ancestral procellariiforms may have resembled Bulweria; that is, they may have been small in size, used natural cavities for nesting, and performed few vocalizations or visual displays. Procellariidae probably diverged from other Procellariiformes in the Eocene, about 40–50 million years ago, coinciding with a wide procellariiform radiation.

Systematics within the family are subject to debate. Because procellariids spend so much time at sea, little is known about them outside of their terrestrial breeding habits. For some species, not even that is known. In addition, the slow rate of speciation makes delineating species difficult. Therefore, debate continues regarding the taxonomy of the family. However, there are four natural groups of Procellariidae. Fulmar-petrels comprise seven species in five genera, ranging from the Arctic to Antarctica. Gadfly-petrels include two genera of 25–36 medium-sized species, some of which are the least known of the family. Prions include seven species in two genera, all of which are found in southern oceans. The shear-waters include 21–26 species in three genera.

Physical characteristics

As Procellariiformes, the procellariids have hooked bills with tubular nostrils. The sharp tip of the bill is an effective implement for handling prey; the tubular nostrils may be related to the well-developed sense of smell used for finding food at great distances and nests in the dark.

Size ranges from 9.1–11 in (23–28 cm) for fairy prions (Pachyptila turtur) to 31.9–39 in (81–99 cm) for giant petrels (Macronectes spp.), which sport wingspans of about 2.2 yards (2 m). Plumage varies among species and consists of whites, blues, grays, browns, and blacks and does not vary by sex or season; juveniles typically resemble adults.

Most procellariidae are awkward on land because of weak legs set far back on the body. Rather than walking on their legs, they tend to shuffle along on the breast and wings. The giant petrels are the exception; they have strong legs suitable for scavenging beached carcasses.

Prions have a unique upper bill that is fringed with lamellae (thin plates) that act like baleen to filter plankton out of the water.

Distribution

Procellariidae can be found in oceans throughout the world. However, the Southern Hemisphere contains far more species than the Northern. Fulmar-petrels prefer cooler waters and are rarely found in subtropic waters. Prions are found in southern temperate subantarctic and Antarctic zones. Shearwaters, the most diverse in terms of habitats used, are found in both hemispheres, from tropical to arctic waters.

Some procellariids undergo migrations of thousands of miles each year; other species remain closer to their breeding grounds year-round. Short-tailed shearwaters (Puffinus tenuirostris) cover 120° of latitude in their annual trek from subantarctic nesting grounds to subarctic feeding grounds. Cory's shearwaters (Calonectris diomedea) tend to disperse and wander outside of the breeding season, with less specific feeding grounds.

Habitat

Procellariids are marine; they come to land almost exclusively to breed.

Behavior

Procellariids are excellent flyers, alternating flapping and dynamic soaring. Shearwaters are named for their ability to dip and glide between waves, just above the ocean surface.

Procellariids have an amazing, but not infallible, homing ability. Records of lost procellariids are not uncommon, and in 1999, a great shearwater (Puffinus gravis) wandered to inland England when it should have been nesting in the South Atlantic.

Procellariids vomit smelly stomach oils on invaders. Fulmarpetrels vomit on intrusive conspecifics at breeding colonies, but other procellariids reserve this tactic for use against predators or nosy humans.

On land, prions, shearwaters, and most gadfly-petrels are nocturnal, perhaps because they are awkward on land and vulnerable to predation by gulls, raptors, and crows.

Vocal communication is most common at breeding colonies, with sounds ranging from coos to growls to shrill cries. Many species are silent at sea, but fulmar-petrels make a raucous gull-like noise when competing for food in large flocks.

Feeding ecology and diet

Almost all procellariids feed exclusively at sea on squid, fish, plankton, and discards from fishing boats. Procellariids use their keen sense of smell to locate food. Giant petrels focus on seal and penguin carcasses but switch to squid, krill, and fish when carcasses are scarce. Prions eat primarily zoo-plankton that they strain through their fringed upper bill. Some prions hydroplane: they submerge the bill as they fly low over the water and filter plankton as they go.

Reproductive biology

Procellarids choose breeding grounds with ready access to the sea. Many species form huge breeding colonies: one sooty shearwater (Puffinus griseus) colony on the Snares Islands contains 2.5 million pairs. Other species, such as giant petrels, breed alone or in small, loose colonies.

Procellariid nests vary from mounds of grass or stones built by giant petrels to cliff ledges used by northern fulmars (Fulmarus glacialis) to burrows used by shearwaters, prions, and gadfly-petrels. The burrow nesters either excavate their own cavities or find abandoned rabbit dens or natural cavities. Few species are forest nesters.

Breeding is usually annual in the local spring or summer. The age of sexual maturity ranges from three to twelve years, with five to six years as the average age of first breeding. Procellariiformes are typically monogamous, mating for life, with pairs using the same nest year after year. One pair of northern fulmars reportedly has used the same nest for at least 25 years.

One white egg is laid that constitutes an average of 12–16% of the female's body weight. Both parents incubate the egg in alternating shifts of 2–14 days for an incubation period of six to nine weeks, depending on species. After hatching, both parents care for the chick, leaving it alone after 2–20 days (as soon as it can regulate its own body temperature). The parents then visit the chick only for feeding. Food consists of fatrich stomach oils produced by partial digestion of the adults' normal diet.

Chicks put on large amounts of fat and quickly outweigh their parents, then slim down to an adult weight before fledging. For example, northern fulmar chicks weigh 33.5 oz (950g) by 40–45 days after hatching. When they fledge at 57 days they weigh 28.2 oz (800 g). The large fat deposits might be insurance against periods of starvation that could occur while parents are away foraging. However, fat stores exceed the amount necessary to survive periods of parental absence and are maintained during fledging—the weight loss prior to fledging is due largely to water loss. Another theory suggests that fat stores are for survival after fledging when chicks must learn to forage for themselves.

As chicks approach full size, they begin to flap their wings around the nest in preparation for the first flight. A week or two after the parents have abandoned the chick, it fledges, flinging itself out to sea. While most chicks survive fledging, introduced (rats and cats) and natural (gulls and raptors) predators pose a threat.

Life expectancy for procellariids is about 15–20 years, although some individuals are known to have lived much longer. Britain's oldest bird, a northern fulmar aged over 50 years, was missing and presumed dead in November 1997.

Conservation status

While some procellariids are thriving, others are among the most threatened of all birds. The breeding population of Zino's petrel (Pterodroma madeira) is estimated to be 20–30 pairs. Estimates put the total Chatham petrel (Pterodroma axillaris) population at 800–1,000 birds. It breeds only on tiny South East Island in the Chatham Islands of New Zealand, where broad-billed prions (Pachyptila vittata) are the primary threat because they kill chicks, eggs, and sometimes adults.

All species face the same challenges: introduced predators, habitat deterioration, and human exploitation. International conservation efforts are protecting breeding grounds. Gough Islands, a South Atlantic breeding ground for great shearwaters and others, was declared a World Heritage Site in 1995 by the United Nations science agency UNESCO. Predator extermination programs show promise. After a 100-year absence, gray (Procellaria cinerea) and blue (Halobaena caerulea) petrels returned to breed on Macquerie Island in 2001 after the complete removal of feral cats.

Significance to humans

Several cultures including Eskimos, Maoris, and Europeans have traditionally eaten procellariid eggs, chicks, and adults. Natives of New Zealand and Tasmania still harvest several thousand chicks annually for feathers, fat, flesh, oil, and down, earning the short-tailed and sooty shearwaters the local nickname of muttonbirds.

On June 20, 2001, the Agreement on the Conservation of Albatrosses and Petrels was signed by seven major fishing nations. The agreement requires member nations to manage fisheries by-catch, protect breeding sites from disturbance, promote conservation in the fishing industry, and conduct research to understand threatened species. A primary goal is to reduce seabird fatalities by long-line fishing. An estimated 300–350,000 seabirds are killed annually while attempting to get long-line bait. Long-liners present a dilemma for conservationists because this fishing technique is considered environmentally good for fish.

Species accounts

List of Species

Cory's shearwater

Calonectris diomedea

taxonomy

Procellaria diomedea Scopoli, 1769, no locality: Tremiti Islands, Adriatic Sea.

other common names

English: Mediterranean/(North) Atlantic shearwater; French: Puffin cendré; German: Gelbschnabel-Sturmtaucher; Spanish: Pardela Ceniciera.

physical characteristics

17.7–18.9 in (45–48 cm); 19.8–33.7 oz (560–956 g); wingspan 39.4–49.2 in (100–125 cm). Heavy bodied. Uniformly pale underneath, with darker gray/brown plumage above; yellow bill. Has lighter cap than the similar greater shearwater.

distribution

Breeds on islands in the eastern North Atlantic and Mediterranean, migrates across the equator to South Atlantic and Indian oceans.

habitat

Marine, nesting on barren offshore islands away from mainland. Nests on rocky slopes, on cliffs, or in caves.

behavior

Cory's shearwaters fly with a slower, more relaxed wingbeat than do other shearwaters.

feeding ecology and diet

Feeds mainly at night on fish, squid, crustaceans, and offal by plunging and surface-seizing. Follows fishing boats.

reproductive biology

Breeding season starts in April. Nests in natural nooks such as burrows or rock crevices. The single white egg is incubated for 54 days. The brown chicks are brooded for approximately four days, fledging after 97 days. Sexual maturity at seven to 13 years.

conservation status

Not threatened.

significance to humans

Regarding the awesome sight of migrating Cory's shearwaters, the Stuarts wrote in Birds of Africa: "Those that breed in the Mediterranean move in from the Atlantic at a rate of some 3,600 birds per hour through the Strait of Gibraltar. At the end of the breeding season when the adults and young birds depart for their overwintering grounds in the open ocean, they stream through the Strait in October to November at an estimated rate of 26,272 each day."

Manx shearwater

Puffinus puffinus

taxonomy

Procellaria puffinus Brünnich, 1764, Faeroes and Norway.

other common names

French: Puffin des Anglais; German: Schwarzschnabel-Sturmtaucher; Spanish: Pardela Pichoneta.

physical characteristics

11.8–15 in (30–38 cm), 12.3–20.3 oz (350–575 g), wingspan 29.9–35 in (76–89 cm). Blackish upper body with contrasting white underneath. Upper parts are much darker than Cory's shearwater; face has more black than the little shearwater. The white undertail coverts contrast with the dark undertail coverts of the black-vented shearwater, once considered a subspecies of the Manx shearwater.

distribution

Breeds on islands on both sides of the North Atlantic, winters in Atlantic off Brazil, Argentina, and South Africa.

habitat

Marine, primarily over continental shelf.

behavior

Gregarious, swims and dives to feed. Dives can be from the surface or from the air, and do not go deep below the water surface. To start the breeding season, males claim abandoned rabbit burrows, then call from within to attract females.

feeding ecology and diet

Feeds on small shoaling fish, squid, crustaceans, and offal. Does not normally feed in large flocks.

reproductive biology

Colonial burrow nester. Breeding season begins in March. The egg, laid in mid-May, is incubated 47–55 days and fledging occurs

after 62–76 days. Young fledge at night to begin a two to three week journey to wintering sites off Brazil, Argentina, and Uruguay. Sexual maturity at 5–6 years.

conservation status

Not threatened.

significance to humans

Formerly hunted for food.

Short-tailed shearwater

Puffinus tenuirostris

taxonomy

Procellaria tenuirostris Temminck, 1835, seas north of Japan and shores of Korea.

other common names

English: Slender-billed shearwater/petrel, Tasmanian mutton-bird; French: Puffin à bec grêle; German: Kurzschwanz-Sturmtaucher; Spanish: Pardela de Tasmania.

physical characteristics

15.7–17.7 in (40–45 cm), 16.9–28.2 oz (480–800 g), wingspan 37.4–39.4 in (95–100 cm). Dark brownish-gray above, lighter underneath. Pale chin, dark bill. Dark feet reach beyond short, square tail.

distribution

Breeds in Tasmania and southern Australia, migrates north across the equator to arctic reaches, including Alaska. Stays primarily in the Pacific.

habitat

Marine, found near land and in open seas. Typically breeds on grassy coastal islands.

behavior

Forms flocks of up to 20,000.

feeding ecology and diet

Fish, crustaceans, and cephalopods. Found with whales. Social feeding is common, including flocking at dawn and dusk to feed on swarming euphausids.

reproductive biology

Breeding season starts in October, forming crowded colonies of burrow nests. The single white egg is incubated for 52–55 days; the dark gray to brown chick in brooded for two to three days; fledging after 94 days. Sexual maturity at 4–6 years in males, five to seven years for females. Can live at least 30 years.

Parents on Montague Island travel up to 9,600 miles (15,450 km) round-trip on feeding voyages, the longest flights known for birds feeding young. Such long journeys may serve more to replenish the adults' reserves, than to feed the young.

conservation status

Not threatened.

significance to humans

Approximately 300,000 chicks are harvested each year from Tasmania.

Northern fulmar

Fulmarus glacialis

taxonomy

Procellaria glacialis Linnaeus, 1761, within the Arctic Circle (Spitsbergen).

other common names

English: Arctic fulmar; French: Fulmar boréal; German: Eissturmvogel; Spanish: Fulmar Boreal.

physical characteristics

With a wingspan of 40.2–44.1 in (102–112 cm), white head, and gray upper body, northern fulmars resemble gulls, but their wings are broader and the neck is thicker. Lighter morphs are more common in Atlantic, darker morphs in Pacific.

distribution

Northern Atlantic and Pacific oceans, has spread southward over much of the Atlantic Ocean. Winters farther south.

habitat

Marine, especially colder waters of the Northern Hemisphere.

behavior

More aggressive in vomiting habits than other procellariids. Stiff wings held out straight from body help to distinguish them from gulls.

feeding ecology and diet

Feed on fish, squid, plankton, and fishing refuse. Feeds in flocks, frequently behind fishing boats. Will scavenge on carrion.

reproductive biology

Breeding season begins in May. The single white egg is incubated 47–53 days; the white to dark gray chick is brooded for 2 weeks; fledging after 46–53 days. Nests colonially on cliff ledges and on level ground, and has expanded to buildings and rooftops.

conservation status

Not threatened. One of few seabirds to increase in numbers and range since 1800. Expansion may be due to food from fishing ship discards or to changing oceanographic conditions. The dependence on fishing ships presents an interesting conservation problem. If ships clean up their refuse, then fulmars may be pushed to feed elsewhere, potentially on smaller birds.

significance to humans

Once hunted for food. Now may be anthropophilic, following fishing ships for food.

Broad-billed prion

Pachyptila vittata

taxonomy

Procellaria vittata G. Forster, 1777, lat. 47°.

other common names

English: Blue/broad-billed dove-petrel, long-billed/common prion, icebird, whalebird; French: Prion de Forster; German: Großer Entensturmvogel; Spanish: Pato-petrel Piquiancho.

physical characteristics

9.8–11.8 in (25–30 cm); 5.6–8.3 oz (160–235 g); wingspan 22.4–26 in (57–66 cm). The largest prion, with a wide bill. Dark patches form an "M" across back of outstretched wings.

distribution

Breeds in South Pacific on New Zealand's South Island and on Chatham Islands, and in the South Atlantic on Gough and Tristan da Cunha Islands.

habitat

Marine, stays away from land except to breed. Breeds on barren areas including lava fields, cliffs, and coastal slopes.

behavior

Prions are social. Courtship displays are restricted to cover of night or burrows. Pairs defend their burrows aggressively with calls, posturing, or if the threat intensifies, with biting of each other's bill and neck.

feeding ecology and diet

Crustaceans (mostly copepods), squid, and fish. Feeds by hydroplaning and by surface-seizing. Does not tend to follow fishing boats. Feeds gregariously.

reproductive biology

Breeding season starts in July or August. Forms tight colonies of burrow nests. More than one pair may occupy one nest. The egg is incubated for 50 days and fledging occurs after 50 days.

conservation status

Not threatened.

significance to humans

None known.

Bermuda petrel

Pterodroma cahow

taxonomy

Aestrelata cahow Nichols and Mowbray, 1916, Castle Island, Bermuda.

other common names

English: Cahow; French: Pétrel des Bermudes; German: Bermudasturmvogel; Spanish: Petrel Cahow.

physical characteristics

15.0 in (38 cm); wingspan 35.0 in (89 cm). Brownish-gray upper body, including a cap that covers the eye and a partial brown collar on the nape. Black bill. White underneath, except for black edges of wings. Easily confused with the larger black-capped petrel.

distribution

Islets in Castle Harbour, Bermuda.

habitat

Marine. Formerly excavated burrows in sand or soft soils, but now nests on small, rocky offshore islands and in artificial burrows.

behavior

Little is known about the natural behavior of these birds. Their normal night-time aerial courtship has been disrupted by lights from human facilities.

feeding ecology and diet

Very little known; not known to follow ships.

reproductive biology

Breeding season January to June. The single white egg is incubated for 51–54 days; the chick is brooded for one or two days; fledging after 90–100 days. Historically it bred inland in soil burrows, but rats have driven colonies to suboptimal, rocky offshore islets.

conservation status

Endangered. Had been thought extinct since 1621 after colonists hunted it for food. In 1921, it was found living, and in 1951, 18 breeding pairs were found. Intensive conservation efforts began in 1961; 45 pairs were found breeding in 1994. Current threats include native species (white-tailed tropicbirds [Phaethon lepturus] compete for nesting sites), human disturbance (light pollution disrupts nocturnal courtship), natural disasters (flooding of nests became a problem in the 1990s, with rising sea levels), and atmospheric pollution. In 1997, the population was estimated at 180 birds.

significance to humans

Formerly hunted for food.

Bulwer's petrel

Bulweria bulwerii

taxonomy

Procellaria bulwerii Jardine and Selby, 1828, Madeira.

other common names

French: Petrel de Bulwer; German: Bulwersturmvogel; Spanish: Petrel de Bulwer.

physical characteristics

10.2–11.0 in (26–28 cm); 2.8–4.6 oz (78–130 g); wingspan 26.8–28.7 in (68–73 cm). One of the smallest procellarids. Dark brown plumage, long wings, flies with tail narrowed to a point.

distribution

Throughout the tropics in eastern Atlantic and Pacific oceans. One study suggests that Bulwer's petrel prefers warm waters of intermediate salinity, while Joaquin's petrel (Bulweria fallax) prefers slightly higher salinity levels.

habitat

Marine, strongly pelaqic. Breeds on barren, remote islands.

behavior

Nocturnal. Both sexes make a barking call known as a "woof." They do not call while flying.

feeding ecology and diet

Feeds primarily at night on fish, squid, some crustaceans and sea-striders, by seizing prey from the surface.

reproductive biology

Breeding season starts in April or May. Nest in burrows, crevices, cracks, caves, or under other cover. The single white egg is incubated for 44 days; the chick is blackish when it hatches; fledging after 62 days.

conservation status

Not threatened.

significance to humans

Collected for food and fish bait on Atlantic islands.

Southern giant petrel

Macronectes giganteus

taxonomy

Procellaria gigantea Gmelin, 1789, Staten Island, off Tierra del Fuego.

other common names

English: Antarctic giant petrel, giant fulmar, stinker, stinkpot; French: Fulmar géant; German: Riesensturmvogel; Spanish: Abanto-marino Antártico.

physical characteristics

Largest procellariid; 33.9–39 in (86–99 cm); male 11 lb (5 kg), female 6.6–17.6 lb (3–8 kg); wingspan 72.8–80.7 in (185–205 cm). Enormous yellow bill. Head, neck, and upper breast are pale; the rest of the body is mottled brown on the dark morph, with the underside lighter than the upper parts. Dark legs. The dark color morph resembles the northern giant petrel, but the less common all-white morph is distinctive.

distribution

Found throughout the Southern Hemisphere from Antarctica to the subtropics of Chile, Africa, and Australia.

habitat

Marine, feeding in coastal and pelagic southern hemisphere waters. Nests on bare or grassy, exposed ground throughout Antarctica, on the coasts of Chile and Argentina, and on subantarctic and Antarctic islands.

behavior

The birds are so tame that researchers can walk up to brooding females and remove chicks from underneath them for study. Their strong legs, unusual for a procellariid, allow the giant petrels to scavenge beached carcasses. The larger males exclude females from carcasses, forcing the females to depend more heavily on live prey taken at sea. Both sexes visit the colony year-round, even outside of the breeding season.

feeding ecology and diet

Shunned, even by avid birders, for feeding on rotting carcasses. Parents travel up to 3,000 miles (4,830 km) to ice packs to feed on krill and squid brought to the surface by ocean upwellings. Gather in the thousands at long-line fishing boats.

reproductive biology

Sexual maturity at six to seven years of age. Breeding season starts in October. Nest is made by gathering grass and moss, or small stones, into a mound, with a depression in the middle. The single white egg is incubated 55–66 days; the whitish chick is brooded for two or three weeks; fledging at 104–132 days.

conservation status

Vulnerable. Total population about 36,000 breeding pairs. Many populations have inexplicably decreased by 30–35% since 1981.

significance to humans

Their long lives (the oldest known lived 50 years) make them a valuable indicator species to judge the health of the Antarctic ecosystem.

Resources

Books

BirdLife International. Threatened Birds of the World. Cambridge: BirdLife International, 2000.

del Hoyo, J., A. Elliot, and J. Sargatal, eds. "Ostrich to Ducks." In Handbook of the Birds of the World. Vol. 1. Barcelona: Lynx Edicions, 1992.

Stuart, Chris, and Tilde Stuart. "Birds of the Oceans." In Birds of Africa from Seabirds to Seed-Eaters. Cambridge, Massachusetts: The MIT Press, 1999.

Warham, John. The Behavior, Population Biology and Physiology of the Petrels. San Diego, CA: Academic Press, 1996.

Periodicals

Braasch, Gary. "Antarctic Mystery." International Wildlife 31 (2001): 52–57.

Phillips, R.A., and K.C. Hamer. "Postnatal Development of Northern Fulmar Chicks, Fulmarus glacialis." Physiological and Biochemical Zoology 73 (2000): 597–604.

Schultz, Mark A., and Nicholas I. Klomp. "Does the Foraging Strategy of Adult Short-Tailed Shearwaters Cause Obesity in Their Chicks?" Journal of Avian Biology 31 (2000): 287–294.

Thompson, Paul M., and Janet C. Ollason. "Lagged Effects of Ocean Climate Change on Fulmar Population Dynamics." Nature 413 (2001): 417–420.

Other

Earth-Life Web Productions."Shearwaters (Procellariidae)." 21 Oct. 2001 (21 Feb. 2002). <http://www.earthlife.net/birds/shearwaters.html>.

Gough, G.A., J.R. Sauer, and M. Iliff. Patuxent Bird Identification Infocenter. 1998. Version 97.1. Patuxent Wildlife Research Center, Laurel, MD. 28 Dec. 2000 (21 Feb. 2002). <http://www.mbr-pwrc.usgs.gov/Infocenter/infocenter.html>.

Barbara Jean Maynard, PhD