Hydrobates macrodactylus 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Procellariiformes Hydrobatidae

Scientific Name: Hydrobates macrodactylus
Species Authority: (Bryant, 1887)
Common Name(s):
English Guadalupe Storm-petrel, Guadalupe Storm Petrel, Guadalupe Storm-Petrel
Oceanodroma macrodactyla Bryant, 1887
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.
Taxonomic Notes: Hydrobates macrodactylus (del Hoyo and Collar 2014) was previously placed in the genus Oceanodroma as O. macrodactyla.
Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered () D ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Howell, S., Keitt, B., Sweet, P. & Tershy, B.
Facilitator/Compiler(s): Anderson, O., Bird, J., Butchart, S., Capper, D., Clay, R., Isherwood, I., Lascelles, B. & Symes, A.
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).

Date last seen: 1912
Previously published Red List assessments:
2010 Critically Endangered (CR)
2009 Critically Endangered (CR)
2008 Critically Endangered (CR)
2006 Critically Endangered (CR)
2005 Critically Endangered (CR)
2004 Critically Endangered (CR)
2000 Critically Endangered (CR)
1996 Critically Endangered (CR)
1994 Critically Endangered (CR)
1988 Threatened (T)

Geographic Range [top]

Range Description: Hydrobates macrodactylus 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 H. leucorhous 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).

Countries occurrence:
Possibly extinct:
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 1
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 1
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Any remaining population is assumed to be tiny (numbering fewer than 50 individuals and mature individuals).
Current Population Trend: Unknown
Additional data:
Number of mature individuals: 1-49 Continuing decline of mature individuals: Unknown
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 1 Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: Yes
No. of individuals in largest subpopulation: 100

Habitat and Ecology [top]

Habitat and 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.

Systems: Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat: Unknown
Generation Length (years): 14.6
Movement patterns: Full Migrant
Congregatory: Congregatory (and dispersive)

Threats [top]

Major Threat(s): 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 [top]

Conservation Actions: 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.

Citation: BirdLife International. 2012. Hydrobates macrodactylus. The IUCN Red List of Threatened Species 2012: e.T22698530A40247343. . Downloaded on 25 November 2015.
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