Justification This species has been extirpated from two islands, and breeding is now restricted to an extremely small area on one island. It qualifies as Critically Endangered because habitat is being degraded by sheep grazing, whilst feral cats are reducing numbers.

Family/Sub-family Procellariidae

Species name author Townsend, 1890

Taxonomic source(s) Brooke (2004)

Taxonomic note Puffinus auricularis (Sibley and Moroe 1990, 1993) has been split into P. auricularis and P. newelli following Brooke (2004).

Identification 33 cm. Medium-sized shearwater. Generally black above and white below. Sharp transition at side of head from black (with some freckling) to white. White underparts except for black half-collar, blackish undertail-coverts and thighs. Prominent white flank patch extending to side of rump. Underwing black around leading and trailing borders sharply demarcated from central white areas. Similar spp. Black-vented Shearwater P. opisthomelas is larger, distinctly brownish and has less clear separation of dark and light areas. Voice Braying notes at colony.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

250-999

decreasing

2,980,000 km²

Yes

Range & population Puffinus auricularis breeds around Cerro Evermann on Socorro in the Revillagigedo Islands, Mexico. In 1981, there were an estimated c.1,000 pairs, with more found in the north of the island in 1990. In 1993-1999, the estimate was c.500 pairs⁴ and fewer than 100 breeding pairs could be located in 2008⁷. However, 46,000 individuals (95% CI = 18,000-89,000), including 10,600 breeding birds, were estimated during at-sea censuses in 1980-1994⁵. It is clear that the breeding range has contracted, and threats indicate that numbers have declined. It formerly bred on Clarión and San Benedicto, but was almost certainly extinct on the former by 1988, and there has been no confirmed breeding on the latter since 1952. However, birds seen immediately north of San Benedicto in 1988 and 1990 provide some hope that a population remains. In the non-breeding season, it forages largely in waters over the continental shelf of Mexico⁵.

Ecology: On Socorro, it breeds in rocky burrows within dense bushy areas at the forest edge. Breeding is concentrated above 700 m ², but observations in 1981 suggested that the major breeding sites were at 500-650 m. Birds have been seen roosting in the naval base at Cape Rule⁴. On Clarión, it nested in burrows on grassy and bracken-covered slopes³.

Threats Cats were introduced to Socorro in the early 1970s, and more than 92% of cat scats above 500 m contain shearwater remains⁴. Reports that rats have recently colonised Socorro are not confirmed⁴. Sheep are destroying nesting habitat across some parts of its colonies, through overgrazing and soil compaction. Pigs were introduced to Clarión soon after 1979, and by 1988 numerous shearwater remains littered burrows destroyed by severe pig rooting. Sheep (introduced in c.1990) and rabbits have also destroyed habitat and nesting sites on Clarión. In 1952, a volcanic eruption obliterated the San Benedicto population. Potential developments on Socorro including enlargements to the airstrip and the possibility of a new federal prison could destroy breeding habitat, increase light pollution and increase the risk of accidental introduction of other invasive species⁸.

Conservation measures underway In 1994, the Revillagigedo Islands were declared a Biosphere Reserve. There are plans to conduct surveys on Clarión and Socorro, with intensive cat-trapping taking place in 2007, but previous efforts have been poorly resourced^6,7. Pigs and sheep were eradicated from Clarión in 2002, but attempted rabbit eradication failed. The installation of an automated playback system to assist the recolonisation of Clarión is under consideration⁶. The Mexican Navy has reduced the sheep population to c.300 individuals⁸.

Conservation measures proposed Eradicate introduced mammals on Socorro and Clarión. Determine whether a breeding population remains on San Benedicto. Assist the recolonisation of Clarión. Continue to monitor numbers on Socorro and at sea.

References Collar et al. (1992). 1. AOU (1998). 2. Brooke (2004). 3. S. N. G. Howell in litt. (1998). 4. J. Martínez Gómez in litt. (1998, 1999, 2000). 5. Spear et al. (1995). 6. B. Tershy and B. Keitt in litt. (1999). 7. J. Martínez-Gomez in litt. (2007, 2008). 8. Martínez-Gómez and Jacobsen (2004).

Further web sources of information

Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

Text account compilers Joe Benshemesh, Phil Benstead (BirdLife International), Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Rob P Clay (Guyra Paraguay), Andy Symes (BirdLife International)

Contributors Steve Howell (Point Reyes Bird Observatory), Brad Keitt (Island Conservation), Juan Esteban Martínez-Gómez (Island Endemics Foundation/Endémicos Insulares), Bernie Tershy (Island Conservation)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Andy Symes (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Puffinus auricularis. Downloaded from http://www.birdlife.org on 10/2/2010

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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