Justification This species has a small breeding range and population which nests at a small number of known locations. The presence of introduced predators on most known and potential breeding islands suggests that numbers are likely to be declining significantly. It consequently qualifies as Vulnerable.

Family/Sub-family Alcidae

Species name author (Salvadori, 1865)

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

Synonyms Brachyramphus craveri Stotz et al. (1996), Brachyramphus craveri Collar and Andrew (1988)

Identification 25 cm. Small, black-and-white alcid. Black upperparts, white below. Black partial collar extending on to sides of breast. Black on head extends just under bill. Partial white eye-ring. Long slim bill. Dusky grey underwing linings. Similar spp. Xantus's Murrelet S. hypoleucus lacks partial breast-band and black extending under bill, and has white underwing linings and shortish, stout bill. Voice Shrill whistle, sometimes given as series.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

9,000 - 15,000

decreasing

950,000 km²

Yes

Range & population Synthliboramphus craveri has an estimated c.5,000 breeding pairs, scattered throughout the Gulf of California, Mexico³. It breeds on Islas Partida, Tiburón, San Jorge, San Esteban, Estanque, San Pedro Mártir, San Pedro Nolasco, San Francisco, Espíritu Santo and San Ildefonso, and possibly on the Pacific coast of Baja California, north to Islas San Benitos^2,3,8,9. The population, with pre-breeders, is probably 15,000-20,000 birds⁴, which is similar to an at-sea survey estimate of c.22,000 birds⁵. It winters in the Gulf of California and along coasts to south California, USA, and Sonora, Mexico, and possibly Guatemala^2,6.

Ecology: Two eggs are usually laid on bare rock or soft substrate at the end of a rock-cavity or crevice, but also in ground-burrows, under dense shrubs and boulders^2,4. Nesting success varies from 12-79%, but chick survival during the first month at sea is only 30-35%². It feeds mainly on larval fish, especially rockfish Sebastes, herring (Clupeidae) and lanternfish Benthosema panamense².

Threats Cats and rats are probably the greatest threat, presumably predating both adults and nests on several breeding islands². Deer mice may also pose a threat on some islands. Oil spills from the tanker lane stretching from the Gulf of California to Puerto Libertad could threaten a large percentage of breeding adults. Pollution from offshore oil-wells or the Los Angeles oil-tanker lane could also affect non-breeding adults in the south California Bight⁹. Further threats are drowning in drift gill-nets, nest-site disturbance and possibly organochlorine pollution⁹.

Conservation measures underway A management plan and implementation strategy for the Gulf of California Special Biosphere Reserve were detailed in 1994⁹, and work began in 1999¹. Introduced mammals have been eradicated from a number of islands that are current, past or potential breeding sites^7,10,11,12. Instructive signs have been placed on many of the islands and there is a general move towards increasing enforcement of existing regulations. At the same time, human use of the islands is increasing, much of it unregulated⁷. Other measures include the development of management plans for all known breeding islands, environmental education, the erection of warning signposts on islands and increased enforcement of existing regulations⁷.

Conservation measures proposed Eradicate introduced predators on other small islands. Monitor all islands for new mammalian introductions. Develop strategies to remove predators from larger islands. Ensure the full implementation of the management plan. Estimate population sizes with precision. Monitor key populations. Assess the impact of gill-net fisheries³. Regulate tourism on Baja California islands⁹.

References 1. D. W. Anderson in litt. (1999). 2. DeWeese and Anderson (1976). 3. Everett and Anderson (1991). 4. Gaston and Jones (1998). 5. Pitman et al. (1995). 6. Tershy et al. (1993). 7. B. Tershy in litt. (1999). 8. E. Velarde in litt. (1998). 9. Velarde and Anderson (1994). 10. Tershy et al. 2002. 11. Aguire et al. (in press). 12. B. Tershy in litt. (2007).

Further web sources of information

Audubon WatchList

Text account compilers Phil Benstead (BirdLife International), James Gilroy (BirdLife International)

Contributors Dave Anderson (Wake Forest University), Bernie Tershy (Island Conservation), E. Verlarde

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), James Gilroy (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Synthliboramphus craveri. 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.

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