Buller's shearwater

Buller's shearwater
Conservation status
	; Vulnerable (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Procellariiformes
Family:	Procellariidae
Genus:	Ardenna
Species:	A. bulleri
Binomial name
	Ardenna bulleri; (Salvin, 1888)

Last updated October 28, 2022

Buller's shearwater (Ardenna bulleri) is a Pacific species of seabird in the family Procellariidae; it is also known as the grey-backed shearwater or New Zealand shearwater. A member of the black-billed wedge-tailed Thyellodroma group, among the larger shearwaters of the genus Ardenna , it forms a superspecies with the wedge-tailed shearwater (A. pacificus).^[2]

Description

Adults birds are 46–47 cm (18–19 in) in length, with a 97–99 cm (38–39 in) wingspan, and have been recorded to weigh 342–425 g (12.1–15.0 oz). The upperside of Buller's shearwater is bluish grey. A blackish stripe runs from the tertiary remiges to the primary wing coverts. The primary remiges are blackish, also; the two black areas do not meet at the hand, however; the area between them is a rather light grey, and under bright light may appear almost white. With the bird facing upwards, the pattern gives the impression of a broken black "M", with light grey interspersing areas.^[3]

The underside is bright white; on the head the upperside's grey extends town to eye height and the white cheeks may shine up conspicuously, as in the smaller shearwaters of Puffinus sensu stricto. The rectrices are blackish and the tail is wedge-shaped; the bill and irises are dark. Fledged juveniles already have the adult's colouration; the nestlings are covered in grey down feathers.^[3]

Compared to other shearwaters, the species is unusually easy to identify at sea by its combination of considerable size and the distinctive, M-shaped banding pattern on its upperside while flying, uniquely among its genus and more akin to some gadfly petrels (Pterodroma), the prions (Pachyptila) and their relative, the blue petrel (Halobaena caerulea). These are all much smaller birds, perhaps two-thirds in length and wingspan and less than half in bulk of Buller's shearwater.^[3]

Range and ecology

This species is pelagic like the other Ardenna shearwaters; it is a transequatorial migrant ranging across most of the Pacific Ocean outside the breeding season. Though it occurs in the subarctic waters off Kamchatka and the Aleutian Islands, it is not documented in the subantarctic Pacific; this apparent absence might simply be due to the lack of study opportunities in the vast islandless region south of the Polynesian Triangle, however. It is fairly common well off the west coast of the United States during late summer and early autumn, and can generally be observed not far from land along the whole temperate and tropical coastlines of the Americas. Its general absence from most of Melanesia and western Micronesia – where human settlement and sea traffic are considerable – is thus probably genuine; only isolated records, such as from the Marianas, Palau, and Yap, exist from west and southwest of the Marshall Islands.^[4] A vagrant bird was also recorded in the Atlantic once, offshore New Jersey, United States.^[3]

Buller's shearwater feeds mainly on fish, squid, and crustaceans such as the krill Nyctiphanes australis . It does occasionally follow ships, such as fishing trawlers, and may be part of a mixed-species feeding flock. Food is caught mainly at a head's length below the surface at most, the bird either picking it up with the bill only, often out of flight, or briefly inserting the entire head, usually while swimming. It neither dives out of flight very often, nor in a plunge off the water's surface.^[3]

It is a colonial nester, breeding predominantly on Tawhiti Rahi and Aorangi, the main islands of the Poor Knights group offshore northern New Zealand.^[5] This bird nests in burrows, rock crevices, or under tree roots, preferring densely forested slopes.^[6] Buller's shearwater can also be found to breed in cracked-up rock on treeless stacks or cliffs, however, and most of the other colonies – on the smaller Poor Knights islands between the main islands and off the southeast of Aorangi^{[ verification needed ]}– are of such a nature. A pair was observed to breed on the Simmonds Islands in 1980,^[7] but this seems to have been an isolated incident.^[3]

The breeding season starts in October and lasts for almost half a year. A single egg is incubated for about 51 days, with the parents changing between incubation and feeding every 4 days or so. Time to fledging is not well known, but by analogy with Buller's shearwater's relatives assumed to be around 100 days.^[3]

In the past, it was heavily used as a food source by the Māori, and on Aorangi it suffered massive predation by feral pigs. Its population had crashed to a low of just 100-200 pairs on Aorangi in the late 1930s. The pigs were removed from the island in 1936, and the shearwater population recovered, numbering 200,000 pairs again in the early 1980s to approach carrying capacity on the island at the end of the 20th century. At all times, however, the colonies at Tawhiti Rahi and on the smaller islets could supply birds for the resettlement of Aorangi, and Buller's shearwater was never considered threatened with extinction in the foreseeable future. Indeed, it is a very abundant bird, with an estimated world population of 2.5 million birds. As it is not known to occur on any larger island in the region outside the Poor Knights Islands, it is classified as vulnerable by the IUCN: a single localized catastrophe could wipe the species out.^[8]

Related Research Articles

Shearwaters are medium-sized long-winged seabirds in the petrel family Procellariidae. They have a global marine distribution, but are most common in temperate and cold waters, and are pelagic outside the breeding season.

The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the diving petrels, the prions, and the shearwaters. This family is part of the bird order Procellariiformes, which also includes the albatrosses and the storm petrels.

The great shearwater is a large shearwater in the seabird family Procellariidae. It breeds colonially on rocky islands in the south Atlantic. Outside the breeding season it ranges widely in the Atlantic.

The sooty shearwater is a medium-large shearwater in the seabird family Procellariidae. In New Zealand, it is also known by its Māori name tītī, and as muttonbird, like its relatives the wedge-tailed shearwater and the Australian short-tailed shearwater.

<span class="mw-page-title-main">Little shearwater</span> Species of bird

The little shearwater is a small shearwater in the petrel family Procellariidae. Despite the generic name, it is unrelated to the puffins, which are auks, the only similarity being that they are both burrow-nesting seabirds.

Puffinus is a genus of seabirds in the order Procellariiformes that contains about 20 small to medium-sized shearwaters. Two other shearwater genera are named: Calonectris, which comprises three or four large shearwaters, and Ardenna with another seven species.

The Christmas shearwater or ʻaoʻū is a medium-sized shearwater of the tropical Central Pacific. It is a poorly known species due to its remote nesting habits, and it has not been extensively studied at sea either.

The wedge-tailed shearwater is a medium-large shearwater in the seabird family Procellariidae. It is one of the shearwater species that is sometimes referred to as a muttonbird, like the sooty shearwater of New Zealand and the short-tailed shearwater of Australia. It ranges throughout the tropical Pacific and Indian Oceans, roughly between latitudes 35°N and 35°S. It breeds on islands off Japan, on the Islas Revillagigedo, the Hawaiian Islands, the Seychelles, the Northern Mariana Islands, and off Eastern and Western Australia.

Audubon's shearwater is a common tropical seabird in the petrel family. Sometimes known as the dusky-backed shearwater, the specific epithet honours the French naturalist Félix Louis L'Herminier.

The short-tailed shearwater or slender-billed shearwater, also called yolla or moonbird, and commonly known as the muttonbird in Australia, is the most abundant seabird species in Australian waters, and is one of the few Australian native birds in which the chicks are commercially harvested. It is a migratory species that breeds mainly on small islands in Bass Strait and Tasmania and migrates to the Northern Hemisphere for the boreal summer.

Townsend's shearwater is a rare seabird of the tropics from the family Procellariidae.

The flesh-footed shearwater is a medium-sized shearwater. Its plumage is black. It has pale pinkish feet, and a pale bill with a distinct black tip. Together with the equally light-billed pink-footed shearwater, it forms the Hemipuffinus group, a superspecies which may or may not have an Atlantic relative in the great shearwater. These large shearwaters are among those that have been separated into the genus Ardenna. Recent genetic analysis indicates evidence of strong divergence between Pacific colonies relative to those in South and Western Australia, thought to be explained by philopatry and differences in foraging strategies during the breeding season.

Newell's shearwater or Hawaiian shearwater (ʻaʻo), is a seabird in the family Procellariidae. It belongs to a confusing group of shearwaters which are difficult to identify and whose classification is controversial. It was formerly treated as a subspecies of the Manx shearwater and is now often placed in Townsend's shearwater. It is endemic to the Hawaiian Islands.

The pink-footed shearwater is a species of seabird. The bird is 48 cm (19 in) in length, with a 109 cm (43 in) wingspan. It is polymorphic, having both darker- and lighter-phase populations. Together with the equally light-billed flesh-footed shearwater, it forms the Hemipuffinus group, a superspecies that may or may not have an Atlantic relative in the great shearwater. These are large shearwaters which are among those that could be separated in the genus Ardenna.

<span class="mw-page-title-main">Black-vented shearwater</span> Species of bird

The black-vented shearwater is a species of seabird. The bird is 30–38 cm in length with a 76–89 cm wingspan. Formerly considered a subspecies of the Manx shearwater, its actual taxonomic relationships are unresolved.

Ardenna is a genus of seabirds in the family Procellariidae. These medium-sized shearwater species were formerly included in the genus Puffinus.

References

↑ BirdLife International (2018). "Ardenna bulleri". IUCN Red List of Threatened Species . 2018: e.T22698182A132632044. doi: 10.2305/IUCN.UK.2018-2.RLTS.T22698182A132632044.en . Retrieved 12 November 2021.
↑ Carboneras (1992), Austin (1996), Austin et al. (2004), Penhallurick & Wink (2004)
1 2 3 4 5 6 7 Carboneras (1992)
↑ Wiles et al. (2004)
↑ Falla, R.A. (1924). "Discovery of a Breeding Place of Buller's Shearwater, Poor Knights Island, N.Z". Emu. 24: 37–43. doi:10.1071/MU924037.
↑ Marchant, S; Higgins, P. J. (1990). Handbook of Australian, New Zealand and Antarctic birds. Oxford University Press (Melbourne and New York). ISBN 0195530683.
↑ IUCN (2008)
↑ Carboneras (1992), IUCN (2008)

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[iucn_status_12_November_2021-1] BirdLife International (2018). "Ardenna bulleri". IUCN Red List of Threatened Species . 2018: e.T22698182A132632044. doi: 10.2305/IUCN.UK.2018-2.RLTS.T22698182A132632044.en . Retrieved 12 November 2021.

[2] Carboneras (1992), Austin (1996), Austin et al. (2004), Penhallurick & Wink (2004)

[carboneras1992-3] 1 2 3 4 5 6 7 Carboneras (1992)

[4] Wiles et al. (2004)

[5] Falla, R.A. (1924). "Discovery of a Breeding Place of Buller's Shearwater, Poor Knights Island, N.Z". Emu. 24: 37–43. doi:10.1071/MU924037.

[6] Marchant, S; Higgins, P. J. (1990). Handbook of Australian, New Zealand and Antarctic birds. Oxford University Press (Melbourne and New York). ISBN 0195530683.

[7] IUCN (2008)

[8] Carboneras (1992), IUCN (2008)

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