Justification This species is listed as Vulnerable because it has a small range, breeding at just nine locations, which is suspected to be undergoing a continuous and rapid decline, largely because of infrastructure development and disturbance at its nesting colonies, possibly exacerbated by marine oil pollution.

Family/Sub-family Phalacrocoracidae

Species name author Ogilvie-Grant & Forbes, 1899

Taxonomic source(s) AERC TAC (2003), Cramp and Simmons (1977-1994), Dowsett and Forbes-Watson (1993), Sibley and Monroe (1990, 1993)

Identification 80 cm. Large, blackish cormorant with bronze-green sheen on back and wings. In breeding season, becomes more glossy, with fine, white flecks on neck. Similar spp. Great Cormorant P. carbo is larger, with stouter bill and white face and chin-patch.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

220,000

decreasing

660,000 km²

No

Range & population There are two subpopulations of Phalacrocorax nigrogularis³. The northern one breeds on islands off the Persian Gulf coasts of Bahrain, United Arab Emirates (UAE), Saudi Arabia, Qatar and possibly Iran (breeding not confirmed since 1972)^2,3,7. The southern subpopulation is apparently much smaller and breeds on one or more islands off the Arabian Sea coast of Oman and in the Gulf of Aden off Yemen (c.60,000 birds in total)^2,3,7,8. Breeding was confirmed at Socotra for the first time in March 2005, when a colony of c.500 birds was found on the islet of Saboniya¹¹. There is no evidence of birds moving between the two subpopulations, although this could be taking place⁹. The overall population is estimated at 110,000 pairs⁸ (330,000⁸ to <500,000¹⁰ individuals). The species has a very small area of occupancy within its limited breeding range. Only 13 colonies are known to be active at the present time^2,7,10, equivalent to nine locations. The three largest colonies contain at least 75% of the world population^2,3,7, with that on the island of Suwad al Janubiyah (hereafter Suwad) in the Hawar archipelago being the largest¹⁰. In the northern population, c.12 colonies have become extinct^2,7,10 since the 1960s, representing a potential decline of up to c.80,000 pairs (c.26% of the subpopulation). In Saudi Arabia, the number of breeding pairs declined by more than 75% during 1980-1992⁷.

Important Bird Areas Click here to view map showing IBAs where species is recorded and triggers any of the IBA criteria.

Ecology: Behaviour This species is highly gregarious, occurring throughout the year in large aggregations^13,14,18. Some seasonal movements are thought to occur, probably related to fish migrations^2,7, where the species travels in large flocks¹² within the Persian Gulf and the Arabian Sea. However it is difficult to separate seasonal movements from dispersal¹⁴, and there is little conclusive information available regarding patterns of movement¹². It is vagrant as far east as West India, and west to the African coast of the Red Sea¹². The breeding season is variable with laying recorded in most months, but each colony is internally synchronised¹². Breeding has been reported to occur on the Kuria Maria islands from June to October¹⁵, on Halne Island in the Persian Gulf from January to March¹⁶, and on the islands off Saudi Arabia in April, May, September, October and November¹⁷. It is suspected that breeding occurs irregularly to in response to locally varying food availability¹⁴. Habitat The species is exclusively marine and occurs within the range of productive upwellings¹³. Breeding It breeds on offshore islands and islets that have shores of level sand or gravel¹². Nonbreeding Outside the breeding season it roosts on coastal cliffs and rocky islets¹². Diet Diet consists principally of small pelagic shoaling fish for which it dives from the surface¹⁸. Information concerning prey species is scarce^{13, 14} although sardines (sardinella sp.), scads (Selar crumenophthalmus and Atule mate), Silverside Atherinomorphus lacunosus, Spotted Half-beak Hemiramphus far and Streaked Rabbit-fish Siganus javus are probably among the species taken¹⁸. Foraging occurs offshore in large groups¹⁵, and is thought to be communal rather than cooperative¹³. Breeding Site Breeding occurs on shores of level sand or gravel, or gently sloping hills free from vegetation¹⁴, since unimpeded access by foot is essential². Nests consist of depressions in the substrate, or in small mounds of substrate, and occur in high density¹³ in colonies that range in size from 50 to tens of thousands of pairs^13,14.

Threats The very high rate of coastal development on the breeding islands is the main threat, since colonies are displaced and may not be able to successfully relocate elsewhere^2,3,7. Colonies suffer from frequent human disturbance, which allows wide-scale predation of eggs by large gulls Larus spp.^2,3,7. The extinction of 12 colonies since the 1960s, is attributed to encroachment by development and prolonged human disturbance¹⁰. The species is very vulnerable to marine oilspills^3,6. For example, in August 1980 an oil-spill of about 20,000 barrels of light crude oil off the coast of Bahrain killed up to 1,000 birds, most of which were this species⁹. As well as direct mortality, reduced immune function and reduced breeding success from oiling and ingestion, oil-spills also deplete fish stocks⁹. As a piscivore the species is susceptible to other marine pollutants such as heavy metals and PCBs (Polychlorinated biphenyls), as well as neurotoxins⁹. Potential threats are posed by fisheries (food depletion), introduced predators on breeding islands, the harvesting of chicks for food^4,7, and persecution^2,4,7. The species is regularly found drowned in fishing traps¹⁰. Ectoparasites may be a problem in some colonies³ , causing breeding cormorants to desert sites or abandon their young to die.³. As a ground nesting species, it is vulnerable to the effects of storms, such as the flooding of nests during heavy rains, as took place on Suwad in November 1997, and the sudden termination of breeding and mass abandonment of chicks, as occurred due to an isolated thunderstorm with strong winds on Suwad in April 2003¹⁰.

Conservation measures underway CITES Appendix II. The species is legally protected in most range states⁷, but not in UAE¹. Research on the species has increased during the last 10 years, and specific conservation measures have been proposed and acted upon, including the protection of some breeding sites.

Conservation measures proposed Continue basic research into its ecology across its range^2,7,9. Continue monitoring throughout its range^2,7. Protect important breeding colonies^2,7. Adopt breeding islands as priority sites in existing oil-spill contingency plans^2,7. Continue public awareness campaigns^2,7. Investigate restoration of certain former colonies².

References 1. Aspinall (1995). 2. Aspinall (1996). 3. Gallagher et al. (1984). 4. Morris (1996). 6. Symens and Suhaibani (1993). 7. Symens et al. (1993). 8. Jennings (2000). 9. Baha El Din (1991). 10. H. King in litt. (2005). 11. S. Aspinall in litt. (2007). 12. del Hoyo et al. (1992). 13. Nelson et al. (2005). 14. Johnsgard (1993). 15. Gallagher and Woodcock (1980). 16. Meinertzhagen (1954). 17. Bundy, Conner and Harrison (1989). 18. King (2004)

Further web sources of information

Fully detailed species accounts from the Threatened birds of Asia: the BirdLife International Red Data Book (BirdLife International 2001), together with new information collated since the publication of the Red Data Book

Text account compilers David Capper (BirdLife International), Jonathan Ekstrom (BirdLife International), Mike Evans (BirdLife International), John Pilgrim (BirdLife International), Joe Taylor (BirdLife International)

Contributors Simon Aspinall, Howard King (Bahrain Bird Recorder)

IUCN Red List evaluators Stuart Butchart (BirdLife International), Joe Taylor (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Phalacrocorax nigrogularis. 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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