Data Zone
Justification of Red List category
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 potential persistence of Hydrobates socorroensis 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).
Population justification
Any remaining population is assumed to be tiny (numbering fewer than 50 individuals and mature individuals).
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 possible persistence of breeding H. socorroensis on the island (although see Howell 2012) 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).
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.
This species is presumed extinct, with its decline likely due to heavy predation of chicks and adults by cats compounded by the destruction and degradation of nesting habitat by goats. If the species is still present on Guadalupe Island, it is highly likely to still be subjected to heavy predation by cats, despite a cat control programme (Hernández-Montoya et al. 2014). There are now reports of feral dogs on the island, which may pose a predation risk, too (McChesney and Tershy 1998). Goats were introduced to the island in the 1700s and numbered in the tens of thousands by 1875; however, they were completely eradicated on the island in 2004 and they are unlikely to return (Garcillán et al. 2008).
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 eradication 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 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).
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 H. leucorhous has darker underwing, but very difficult to separate.
Text account compilers
Lascelles, B., Martin, R., Miller, E., Stuart, A., Symes, A., Westrip, J., Capper, D., Clay, R.P., Anderson, O., Fjagesund, T., Butchart, S., Bird, J., Hermes, C., Isherwood, I.
Contributors
Tershy, B., Keitt, B., Sweet, P., Howell, S.
Recommended citation
BirdLife International (2024) Species factsheet: Guadalupe Storm-petrel Hydrobates macrodactylus. Downloaded from
https://datazone.birdlife.org/species/factsheet/guadalupe-storm-petrel-hydrobates-macrodactylus on 18/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 18/12/2024.