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Phalacrocorax featherstoni 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Suliformes Phalacrocoracidae

Scientific Name: Phalacrocorax featherstoni Buller, 1873
Common Name(s):
English Pitt Shag
Synonym(s):
Stictocarbo featherstoni ssp. featherstoni (Buller, 1873) — Turbott (1990)
Taxonomic Source(s): Turbott, E.G. 1990. Checklist of the Birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Identification information: 63 cm. Medium-sized, slight grey-and-black cormorant. Breeding, black head, rump, tail, thighs. Dark grey upperparts with small black spots over wings, back. Grey underparts. Apple-green facial skin. Double crest on head. Non-breeding, no crest. Yellow facial skin. Paler underparts. Voice Displaying male noisy, female silent.

Assessment Information [top]

Red List Category & Criteria: Endangered A2bde+3bde+4bde; C1+2a(ii) ver 3.1
Year Published: 2017
Date Assessed: 2017-10-01
Assessor(s): BirdLife International
Reviewer(s): Symes, A.
Contributor(s): Bell, B., Bell, B., Bester, A., Debski, I., Hitchmough, R. & Weeber, B.
Facilitator/Compiler(s): Benstead, P., Harding, M., Mahood, S., McClellan, R., Pilgrim, J., Taylor, J., Westrip, J.
Justification:
This species is listed as Endangered because it has a very small population which has declined rapidly, which is predicted to continue given current threats.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Phalacrocorax featherstoni is found in the Chatham Islands, New Zealand, on Chatham, Pitt, Mangere, Little Mangere, South East (= Rangatira), Star Keys, the Pyramid, Big and Middle Sister, Murumurus, the Castle and Rabbit Islands (Marchant and Higgins 1990, Imber 1994, Taylor 2000). The population has been variously estimated at c.500 pairs, fewer than 1,000 pairs (Heather and Robertson 1997) and in 1997-1998, at 729 pairs, following a complete census over the entire breeding range (Bell and Bell 2000). However, new information suggests that the population has declined, with 547 pairs counted in the second complete census over the 2003-2004 breeding season (Bester and Charteris 2005), and 434 pairs estimated in 2011-2012 (Debski et al. 2012).

Countries occurrence:
Native:
New Zealand
Additional data:
Estimated area of occupancy (AOO) - km2:22Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:13400
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:11-100Continuing 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:A total of 434 pairs (=868 mature individuals; roughly equating to 1,300 total individuals) were counted in the third complete census over the 2011-2012 breeding season.

Trend Justification:  The species's population has declined by 40% over 14 years from 1997 to 2011 (Debski et al. 2012), this would equate to a decline of 61.7% over 3 generations, placed here in the range 50-79%.

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:868Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:2-100Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No
No. of individuals in largest subpopulation:1-89

Habitat and Ecology [top]

Habitat and Ecology:It nests in small colonies of between one and 44 pairs (Debski et al. 2012), on rocky shores and islets, headlands and cliffs. Breeding distribution is limited by suitable nesting sites (Marchant and Higgins 1990). It feeds primarily on small fish, supplemented by marine invertebrates (Heather and Robertson 1997). The species shows foraging area fidelity and may forage up to 18 km away from breeding colonies, with the mean distance of 5.2 km (Bell 2015). They forage in shallow water, with mean dive depth of 6.6 m (max 24.4 m, but with 90% of all dives being <13 m deep) (Bell 2015). Mean dive duration has been estimated at 22 seconds (max 69 seconds), with a mean rest period of 19 seconds (Bell 2015).
Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):8.7
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): The effects of introduced species on Chatham and Pitt Islands are not known, with birds tending to nest in inaccessible sites. Some nests, however, could be affected by stock, feral cats, pigs, dogs, black rats Rattus rattus, brown rats R. norvegicus and Weka Gallirallus australis (Taylor 2000, Bell 2015). Birds are sometimes illegally shot by fishermen (Heather and Robertson 1997, Taylor 2000). A total of 40-80 birds may be caught in crayfish pots annually (Bell and Bell 2000), but changes to fishing practice may have potentially reduced bycatch (Bell 2012). Recent declines may be a response to changes in the marine environment that are affecting food supplies (Bester and Charteris 2005). The species is potentially threatened by climate change because it has a geographically bounded distribution: it is restricted to an island or islands with a maximum altitude of 283 m (Birdlife International unpublished data).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
In 1961, sheep and cattle were removed from South East Island and, in 1968, sheep were taken off Mangere Island (Taylor 2000).

Conservation Actions Proposed
Census the entire adult population once a suitable methodology has been developed, and at 10-year intervals thereafter, and monitor two accessible colonies annually to determine trends (Taylor 2000). Assess the impact of rock lobster fishing practices (B. Weeber in litt. 2000). Remove feral cats and G. australis from Pitt Island if agreement is reached with residents, and remove sheep, cattle and pigs from parts of Pitt and Chatham Islands that are suitable for colonies. Fence colonies (with owners' permission) if stock are found to be impacting on colonies (Taylor 2000). Conduct further research into the breeding biology and foraging ecology of the species (Bell 2015, I. Debinski in litt. 2016).


Citation: BirdLife International. 2017. Phalacrocorax featherstoni. The IUCN Red List of Threatened Species 2017: e.T22696907A117733030. . Downloaded on 20 April 2018.
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