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 O. leucorhoa 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).

Family/Sub-family Hydrobatidae

Species name author Bryant, 1887

Taxonomic source(s) AOU checklist (1998 + supplements), Brooke (2004), Sibley and Monroe (1990, 1993), Stotz et al. (1996)

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.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

<50

unknown

-

Yes

Range & 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. Its non-breeding range is unknown.

Ecology: It nested in burrows 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 measures underway Guadalupe is designated as a Biosphere Reserve¹, but until recently there was little active management³. Nearly 35,000 goats were removed in 1970 and 1971², but many remained until 2004 when a comprehensive programme was carried out, resulting in the complete eradadication of goats from the island⁶. There is potential to remove other introduced species by 2010 with fundraising for cat eradication underway^3,4. A grant has been made available to fund searches for the species on Guadalupe⁵.

Conservation measures 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 et al. (1992). 1. S. N. G. Howell in litt. (1998). 2. P. Sweet in litt. (1996). 3. B. Tershy and B. Keitt in litt. (1999). 4. Tobias et al. (2006). 5. B. Tershy in litt. (2006). 6. Garcillán et al. (2008).

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 Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), David Capper (BirdLife International), Rob P Clay (Guyra Paraguay), Isabel Isherwood (BirdLife International), Ben Lascelles (BirdLife International), Andy Symes (BirdLife International)

Contributors Steve Howell (Point Reyes Bird Observatory), Brad Keitt (Island Conservation), Paul Sweet (American Museum of Natural History), 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: Oceanodroma macrodactyla. 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.

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

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