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.
Brooke, M. de L. 2004. Albatrosses and Petrels Across the World. Oxford University Press, Oxford.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
Distribution and populationPuffinus auricularis
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.
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 pairs (J. Martínez Gómez in litt.
1998, 1999, 2000) and fewer than 100 breeding pairs could be located in 2008 (J. Martínez-Gomez in litt
. 2007, 2008, 2009). However, 46,000 individuals (95% CI = 18,000-89,000), including 10,600 breeding birds, were estimated during at-sea censuses in 1980-1994 (Spear et al.
1995). 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. 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 Mexico (Spear et al.
1995). Population justification
Surveys in 2008 found fewer than 100 breeding pairs on Socorro, suggesting that even accounting for immature and non-breeding birds the total global population may be as low as 250-999 mature individuals, and that previous at sea estimates (which were subject to a high degree of error) may have been too large (J. Martínez-Gomez in litt.
2008). This estimate equates to 375-1,499 individuals in total, rounded here to 350-1,500 individuals.Trend justification
A rapid population decline over the last three generations is estimated from surveys carried out since 1980, but exact trends are difficult to determine owing to inconsistencies between estimates of the breeding population and total numbers at sea (Brooke 2004). A noticeable reduction in nesting colonies has occurred since the observations of Martínez-Gómez and Jacobsen (2004), (J. Martínez-Gómez in litt.
On Socorro, it breeds in rocky burrows within dense bushy areas at the forest edge. Breeding is concentrated above 700 m (Brooke 2004)
, 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 Rule (J. Martínez Gómez in litt.
1998, 1999, 2000)
. On Clarión, it nested in burrows on grassy and bracken-covered slopes (S. N. G. Howell in litt
Cats were introduced to Socorro in the early 1970s, and more than 92% of cat scats above 500 m contain shearwater remains (J. Martínez Gómez in litt.
1998, 1999, 2000)
. Reports that rats have recently colonised Socorro are not confirmed (J. Martínez Gómez in litt.
1998, 1999, 2000)
. 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 the possibility of a new federal prison could destroy breeding habitat, increase light pollution and increase the risk of accidental introduction of other invasive species (Martínez-Gómez and Jacobsen 2004)
. Work to enlarge the airstrip in summer 2009 was believed to have caused the deaths of several birds which were attracted to lights during night-time construction works (J. Martínez-Gomez in litt
. 2007, 2008, 2009)
. Having a distribution on relatively low-lying islands, this species is potentially susceptible to climate change through sea-level rise and shifts in suitable climatic conditions (Birdlife International unpublished data)
. Conservation Actions 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 (B. Tershy and B. Keitt in litt
. 1999, J. Martínez-Gomez in litt
. 2007, 2008, 2009). Pigs and sheep were eradicated from Clarión between 2001 and 2004, but attempted rabbit eradication failed. The eradication of sheep from Socorro began in 2009 with result that only very few remain in 2011; this should be complete within a few years (A. Aguirre in litt.
2012). 83 cats have been killed to June 2012 on Socorro, and an attempted eradication is underway (A. Aguirre in litt.
2012). The installation of an automated playback system to assist the recolonisation of Clarión is under consideration (B. Tershy and B. Keitt in litt
. 1999). Conservation Actions 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. Conduct high-level lobbying to raise awareness of the effect military operations may have on the species.
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.
Brooke, M. De L. 2004. Albatrosses and petrels across the world. Oxford University Press, Oxford.
Collar, N. J.; Gonzaga, L. P.; Krabbe, N.; MadroÃ±o Nieto, A.; Naranjo, L. G.; Parker, T. A.; Wege, D. C. 1992. Threatened birds of the Americas: the ICBP/IUCN Red Data Book. International Council for Bird Preservation, Cambridge, U.K.
Martinez-Gomez, J.E. and Jacobsen, J.K. 2004. The conservation status of Townsend's shearwater Puffinus auricularis auricularis. Biological Conservation 116(1): 35-47.
Spear, L. B.; Ainley, D. G.; Nur, N.; Howell, S. N. G. 1995. Population size and factors affecting at-sea distributions of four endangered Procellariids in the tropical Pacific. Condor 97: 613-638.
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.
Click here for more information about the Alliance for Zero Extinction (AZE)
Explore HBW Alive for further information on this species
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Text account compilers
Benstead, P., Bird, J., Butchart, S., Clay, R., Martin, R, Symes, A.
Howell, S., Keitt, B., Martínez-Gómez, J., Tershy, B.
BirdLife International (2014) Species factsheet: Puffinus auricularis. Downloaded from
http://www.birdlife.org on 29/12/2014.
Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 29/12/2014.
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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