Puffinus bulleri

Buller's shearwaters return to the Poor Knights Islands in mid-September to court females and clean out their burrows before breeding (7). Nesting occurs in large, dense colonies (5), with egg-laying beginning in October (2) (7). The single white egg is incubated by both sexes for about 51 days, and most chicks fledge at around 90 days (5). The following April to late May sees the colonies departing once more for the north Pacific (5) (7). The diet consists of krill, small fish, squid and jellyfish (6), and birds have only recently started to scavenge fishing boat scraps (5).

Buller's shearwater has been described as flying with a grace and economy like no other, characterised by longer gliding motions and less wing flapping, each bird arcing and tilting seemingly without effort (3) (4). In flight, a dark bar on the pale grey wings and lower back forms an unmistakable and arresting 'M'-shaped pattern from above (3) (4), easily distinguishing this shearwater from any other (2). Upperparts are otherwise brownish-grey, while underparts are white (2). The grey, wedge-shaped tail is broadly tipped in black, the long, slender bill is bluish grey with a darker tip, and the legs and feet are pink (5) (6).

Breeds islands off New Zealand; wide transpacific dispersal.

New Zealand Exclusive Economic Zone, South Pacific

Puffinus 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 stacks⁴. In the 1980s, one pair was found breeding on the Simmonds Islands, in the far north of New Zealand⁵. Between 1938 and 1981, the population on Aorangi increased from c.200 to c.200,000 pairs^2,3. The total population is estimated at 2.5 million birds⁴, but it is unclear whether the population on Aorangi is still increasing⁵. It migrates to the northern Pacific Ocean, from Japan to North America and east to California, and is occasionally found off South America^3,5.

Occurs (regularly, as a native taxon) in multiple nations, but breeds in a single state or province

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Transient

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Transient

Global Range: (<100 square km (less than about 40 square miles)) Breeding occurs on the Poor Knights Islands near North Island, New Zealand. One pair was found breeding on the Simmonds Islands (north of New Zealand) in the 1980s. In the nonbreeding season, this species occurs on the Pacific Ocean off the west coast of North America from the Gulf of Alaska to Baja California; near the Hawaiian Islands and Galapagos Islands; off the Kuriles; and off the western coast of South America from Ecuador to Chile (AOU 1998); and to southward to Australian waters (Sibley and Monroe 1990). In North America, it most common from Washington to central California; rarer north and south along the west coast (National Geographic Society 1983).

Coded range extent refers to the terrestrial nesting range. The total area of the Poor Knights Islands is around 24 square kilometers.

Amazingly, the estimated population of some 2,500,000 birds breeds on just one small island group (Poor Knights Islands) off New Zealand, where it is restricted to two main islands, Aorangi and Tawhiti Rahi, and five other islets and stacks. In the non-breeding season, these masses migrate to the north Pacific Ocean, from Japan to North America, and are occasionally found off South America (6).

Length: 41 cm

Weight: 380 grams

breeding near New Zealand

Habitat and Ecology

Systems

• Terrestrial
• Marine

Depth range based on 568 specimens in 1 taxon.
Water temperature and chemistry ranges based on 370 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 11.144 - 17.806
  Nitrate (umol/L): 0.071 - 4.675
  Salinity (PPS): 30.381 - 34.648
  Oxygen (ml/l): 5.473 - 6.583
  Phosphate (umol/l): 0.330 - 0.800
  Silicate (umol/l): 1.436 - 16.169

Graphical representation

Temperature range (°C): 11.144 - 17.806

Nitrate (umol/L): 0.071 - 4.675

Salinity (PPS): 30.381 - 34.648

Oxygen (ml/l): 5.473 - 6.583

Phosphate (umol/l): 0.330 - 0.800

Silicate (umol/l): 1.436 - 16.169
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Comments: Nests are in burrows or rock crevices or under tree roots, on densely forested slopes, as on the larger of the Poor Knights Islands; or in crevices among rocks on treeless stacks or cliffs, such as on the smaller of the Poor Knights Islands. Otherwise the species is pelagic.

This marine, pelagic bird comes to shore only to breed (2), nesting in burrows, rock-crevices and ledges, often under dense vegetation (6).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

This species usually is seen off the west coast of North America during southward migration. It is a rare passage migrant in the central tropical Pacific, recorded at sea near Hawaii mainly in April and August-November (Pratt et al. 1987). It arrives in New Zealand coastal waters in September and almost all depart by the end of May (Jenkins 1988).

Comments: Diet includes fishes (e.g., Pacific saury), squids and crustaceans obtained at or near the surface of the water..

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 1 - 5

Comments: This species is represented by nesting occurrences on just a few islands, with most on just two islands (Tawhiti Rahi and Aorangi)..

>1,000,000 individuals

Comments: Total adult population size is not precisely known but has been estimated at 2,500,000 (Marchant and Higgins 1990).

Egg laying occurs mostly in late November. Clutch size is 1.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 7
Specimens with Barcodes: 9
Species With Barcodes: 1

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 7 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Vulnerable
• 2006
  Vulnerable
• 2004
  Vulnerable
• 2000
  Vulnerable

Canada

Rounded National Status Rank: NNA - Not Applicable

United States

Rounded National Status Rank: NNA - Not Applicable

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Very small bmall breeding range on islands near North Island, New Zealand; large population size; ranges widely at sea in the Pacific Ocean.

Classified as Vulnerable (VU) on the IUCN Red List 2006 (1).

Population

Population Trend

Global Short Term Trend: Relatively stable to increase of 25%

Comments: Population probably is stable or increasing, but better informatrion is needed.

Degree of Threat: Low

Comments: Feral pigs decimated the population nesting on Aorangi, but the shearwater population recovered after pigs were eliminated. Accidental introduction of non-native species is an ongoing potential threat on all islands.

Mortality occurs as incidental catch in fisheries, but the impact of this on the shearwater population is unknown.

Formerly this species was harvested by the Maori.

Major Threats

Buller's shearwater was previously caught in drift-nets in the north Pacific, with an estimated 4,000 birds killed annually, and may still be at risk from set-nets (6) (8). Longline fishing, trawling operations, and hand-and-reel lines may also pose a threat, although little documented evidence of this exists (6) (8). Furthermore, this bird's very limited breeding range renders it extremely vulnerable to the effects of accidentally introduced predators, disease, storms and other catastrophes (6) (8). Indeed, the dense colonies nesting on the Poor Knights Islands were once devastated by introduced pigs. Thankfully, after the eradication of the pigs the shearwaters recovered spectacularly and now have a healthy, growing population, but the potential risk to a bird with such a small breeding range nevertheless remains (4).

Conservation Actions

Biological Research Needs: Level of incidental take in fisheries needs to be determined.

Global Protection: Few (1-3) occurrences appropriately protected and managed

Comments: The Poor Knights Islands are a marine reserve (fishing not permitted), and entry onto the islands is prohibited without a permit.

There was a massive increase in the population after the eradication of feral pigs from Aorangi in 1936, with recolonising populations probably coming from the nearby predator-free island, Tawhiti Rahi (6). The large population is thought to be continuing to grow on the Poor Knights Islands, a protected, now predator-free nature reserve, and if it succeeds in expanding its range, this species may be downlisted to Near Threatened on the IUCN Red List (6) (7).