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Guadalupe Storm-petrel Hydrobates macrodactylus
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Justification
This formerly abundant species has not been recorded since 1912, despite several subsequent searches, and it may well have been driven extinct by feral cats, with declines compounded by nesting habitat destruction by goats. However, it cannot yet be presumed to be Extinct because there have been no thorough surveys of this difficult-to-detect species in the appropriate season since 1906, and relatively recent reports of unidentified storm-petrels calling at night, plus the persistence of Leach's Storm-petrel breeding on the island provide some hope that it may survive. Any remaining population is likely to be tiny, and for these reasons it is treated as Critically Endangered (Possibly Extinct).

Taxonomic source(s)
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.

Taxonomic note
Hydrobates macrodactylus (del Hoyo and Collar 2014) was previously placed in the genus Oceanodroma as O. macrodactyla.

Synonym(s)
Oceanodroma macrodactyla Bryant, 1887

Identification
23 cm. Largish, fork-tailed storm-petrel with white rump. Generally blackish-brown above with paler grey wing-bar. White uppertail patch with darker median stripe extending to lateral coverts. Moderately forked tail. Underparts slightly paler than upperparts. Similar spp. Intermediate Leach's Storm-petrel O. leucorhoa has darker underwing, but very difficult to separate.

Distribution and population
Oceanodroma macrodactyla may persist on Guadalupe, Mexico, 280 km west of Baja California. It was abundant in 1906, but the last record of a breeding bird was in 1912. Searches in 1922, 1925 and the early 1970s failed to find the species. However, there has been no thorough survey in the appropriate season since 1906. Relatively recent reports of storm-petrels calling at night and the apparent persistence of breeding Leach's Storm-petrel O. leucorhoa on the island raises some hope that it may survive, although this is unlikely unless it is able to nest in rock crevices in areas inaccessible to cats (Keitt et al. 2009).

Population justification
Any remaining population is assumed to be tiny (numbering fewer than 50 individuals and mature individuals).

Ecology
It nested in burrows at high elevations in soft soil under pines Pinus radiata var. binata and cypress Cupressus guadalupensis groves. Eggs are known to have been laid between early March and late June.

Threats
The main cause of its demise is thought to be heavy predation by feral cats, compounded by goats destroying and degrading nesting habitat.

Conservation Actions Underway
Guadalupe is designated as a Biosphere Reserve (S. N. G. Howell in litt. 1998), but until recently there was little active management (B. Tershy and B. Keitt in litt. 1999). Nearly 35,000 goats were removed in 1970 and 1971 (P. Sweet in litt. 1996), but many remained until 2004 when a comprehensive programme was carried out, resulting in the complete eradication of goats from the island (Garcillán et al. 2008). There is potential to remove other introduced species by 2010 with fundraising for cat eradication underway (B. Tershy and B. Keitt in litt. 1999, Tobias et al. 2006). A grant has been made available to fund searches for the species on Guadalupe (B. Tershy in litt. 2006). Conservation Actions Proposed
Survey the entire island during the breeding season to ascertain if it is still extant. Eradicate introduced predators and herbivores. Birders on pelagic trips off California should be aware of this species and its identification.

References
Collar, N. J.; Gonzaga, L. P.; Krabbe, N.; Madroño 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.

Garcillán, P. P.; Ezcurra, E.; Vega, E. 2008. Guadelupe Island: lost paradise recovered? Overgrazing impact on extinction in a remote oceanic island as estimated through accumulation functions. Biodiversity and Conservation 17(7): 1613-1625.

Keitt, B. S.; Henry, R. W.; Aguirre, A.; Garcia, C.; Mendoza, L. L.; Hermosillo, M. A.; Tershy, B.; Croll, D. 2006. Impacts of introduced cats (Felis catus) on the Guadalupe island ecosystem. In: Prado, G. K. S., Peters, E. (ed.), Taller sobre la restauración y conservación de Isla Guadalupe: memorias., pp. 10. Instituto Nacional de Ecología, Mexico City.

Tobias, J. A.; Butchart, S. H. M.; Collar, N. J. 2006. Lost and found: a gap analysis for the Neotropical avifauna. Neotropical Birding: 4-22.

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

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Anderson, O., Bird, J., Butchart, S., Capper, D., Clay, R., Isherwood, I., Lascelles, B., Symes, A.

Contributors
Howell, S., Keitt, B., Sweet, P., Tershy, B.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Hydrobates macrodactylus. Downloaded from http://www.birdlife.org on 26/11/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/11/2014.

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.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Critically Endangered - Possibly Extinct
Family Hydrobatidae (Northern Storm-petrels)
Species name author Bryant, 1887
Population size 1-49 mature individuals
Population trend Unknown
Distribution size (breeding/resident) 1 km2
Country endemic? Yes
Links to further information
- Additional Information on this species