Ardenna bulleri 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Procellariiformes Procellariidae

Scientific Name: Ardenna bulleri (Salvin, 1888)
Common Name(s):
English Buller's Shearwater
Spanish Pardela Dorsigrís
Ardenna bulleri ssp. bulleri (Salvin, 1888) — Christidis and Boles (2008)
Puffinus bulleri Salvin, 1888
Taxonomic Source(s): Turbott, E.G. 1990. Checklist of the Birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Taxonomic Notes: Ardenna bulleri (del Hoyo and Collar 2014) was previously placed in the genus Puffinus.
Identification information: 46 cm. Large, grey, black-and-white shearwater with broad wings, buoyant flight and wedge-shaped tail (normally folded). Blackish-brown head, neck. Grey wings, back with large dark "M" across wings. Grey uppertail with black tip. White underparts, underwing. Slim, grey bill with dark tip. Similar spp. Unlike any other Pacific shearwater. Juan Fernández Petrel Pterodroma externa has dark leading edge to underwing. Voice Generally quiet at sea. Assorted howlings, wailings at colony. Calls are very similar to those of Sooty Shearwater P. griseus (G. Taylor in litt. 2012).

Assessment Information [top]

Red List Category & Criteria: Vulnerable D2 ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Szabo, M., Taylor, G.A. & Tennyson, A.
Facilitator/Compiler(s): Benstead, P., Calvert, R., Mahood, S., McClellan, R., Moreno, R., Taylor, J.
This species qualifies as Vulnerable because the population is restricted to a very small area when breeding, and remains at risk from the accidental introduction of predators and other catastrophes. If it succeeds in expanding its range, it may be downlisted to Near Threatened.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Ardenna bulleri breeds only at the Poor Knights Islands, New Zealand. The species is restricted to two main islands, Aorangi and Tawhiti Rahi, and five other islets and stacks (Marchant and Higgins 1990). In the 1980s, one pair was found breeding on the Simmonds Islands, in the far north of New Zealand (Taylor 2000). Between 1938 and 1981, the population on Aorangi increased from c.200 to c.200,000 pairs (Harper 1983, Heather and Robertson 1997). However, surveys in 2011-13 suggested that there are around 100,000 burrows, similar to estimates from Bartle in 1960s (Waugh et al. 2013). In 2011, breeding success on Aorangi Island was noted to be very low, with only 16 chicks found in the 150 burrows sampled (G. Taylor in litt. 2012). The total population has been estimated at 2.5 million birds (Marchant and Higgins 1990), although this now regarded as too high (G. Taylor in litt. 2012, Waugh et al. 2013). It migrates to the northern Pacific Ocean, from Japan to North America and east to California, and is occasionally found off South America (Heather and Robertson 1997, Taylor 2000). The main non-breeding moult zone appears to be the Emperor Seamounts, a chain of underwater volcanos NW of Hawaii (G.Taylor in litt. 2016).

Countries occurrence:
American Samoa; Australia; Canada; Chile; Cook Islands; French Polynesia; Marshall Islands; Mexico; New Caledonia; New Zealand; Niue; Norfolk Island; Peru; Russian Federation (Eastern Asian Russia); United States; United States Minor Outlying Islands; Wallis and Futuna
Fiji; Japan
Present - origin uncertain:
Costa Rica; Ecuador; French Southern Territories; Kiribati; Micronesia, Federated States of ; Nauru; Samoa; Solomon Islands; Tokelau; Tonga; Tuvalu; Vanuatu
Additional data:
Estimated area of occupancy (AOO) - km2:2Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:135000000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):200
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The total population is estimated at 2.5 million birds (Marchant and Higgins 1990), although this is now likely to be too high (G. Taylor in litt. 2012, Waugh et al. 2013).

Trend Justification:  Pigs were exterminated on Aorangi in 1936 and the population has increased since then, although it is now suspected to be stable or decreasing (G. Taylor in litt. 2012, Waugh et al. 2013).

Current Population Trend:Stable
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:It nests in burrows or on rock-crevices and ledges, often under dense vegetation. It feeds on krill, small fish, salps and jellyfish (Marchant and Higgins 1990, Heather and Robertson 1997).

Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):18.3
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): It was previously caught in north Pacific drift-nets (Gould et al. 1998), and is still potentially at risk from set-nets. It may be caught on longlines, in trawling operations and on hand and reel lines, but little documented evidence is available (Taylor 2000, Tennyson et al. 2012). Domestic pigs were previously a threat (removed in 1936), and the species would be at risk of mammalian predators if introduced. The species is potentially threatened by climate change because it has a geographically bounded distribution: it is restricted to an island or islands with a maximum altitude of 218 m (BirdLife International, unpublished data). Poor breeding success recorded on Aorangi Island in 2011 may have been related to a strong La Niña climate pattern in 2010-2011, but data from some birds fitted with geolocators indicated that incubation shifts were around twice the length of those published in the 1980s (G. Taylor in litt. 2012). There has been intensive purse-seine fishing of pelagic fish in the Hauraki Gulf in recent decades, which may have impacted the species through food resource depletion, as it is known to feed in these areas and, perhaps connected to this, populations of Red-billed Gulls Larus scopulinus on the Mokohinau Islands have crashed from c.20,000 birds in the 1960s to fewer than 500 birds in 2011 (G. Taylor in litt. 2011). Further investigation is required.

Conservation Actions [top]

Conservation Actions:

Conservation Actions Underway

The eradication of pigs from Aorangi in 1936 caused a massive increase in the population, with the recolonisation probably coming from the nearby predator-free island, Tawhiti Rahi (Heather and Robertson 1997). Fishing has been banned at the Poor Knights Islands Marine Reserve since 1996 and entry onto the island reserve is prohibited (Szabo in litt. 2004). The International Maritime Organisation (IMO) established the world's first mandatory "area to be avoided" (ATBA) for large shipping vessels, including oil tankers, around the islands in 2004 (Szabo in litt. 2004). Breeding islands have permanent poisoned bait stations and each island is checked every year for any evidence that rodents have arrived (G. Taylor in litt. 2012). The species has been the subject of tracking studies utilising geolocators (2011-2013). These data show the birds are a pelagic species, making extensive use of oceanic seas well east of the North Island (including the Louisville Ridge), and also the Chatham Rise and Bounty Trough (east of the South Island) during the breeding season and migrate to the Emperor Seamounts in the NW Pacific Ocean during the austral winter (G. Taylor in litt. 2016).

Conservation Actions Proposed

Complete an accurate population census (including on Aorangi Island, to better assess breeding numbers (Waugh et al. 2013), assess the current status of breeding on Simmonds Islands and identify any signs of prospecting on other island groups. Establish monitoring plots on Poor Knights to determine the rate and pattern of colony expansion (Taylor 2000). Quantify the impact of bycatch during fishing activities and also assess whether competition with commercial fisheries for surface shoaling fish may be affecting the breeding population. If judged necessary, work with fisheries to develop bycatch reduction measures. 

Citation: BirdLife International. 2016. Ardenna bulleri. The IUCN Red List of Threatened Species 2016: e.T22698182A93667529. . Downloaded on 18 August 2018.
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