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Auckland Islands Shag Phalacrocorax colensoi

Justification
This species is classified as Vulnerable because it has a very small range when breeding, being locally restricted to inaccessible coastline sites, and is therefore susceptible to stochastic events and human impacts. Population trends are unknown, but are assumed to be stable.

Taxonomic source(s)
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.

Synonym(s)
Leucocarbo colensoi Turbott (1990), Leucocarbo colensoi colensoi Turbott (1990)

Identification
63 cm. Medium-sized, black-and-white cormorant. Black head, hindneck, lower back, rump, uppertail-coverts, all with metallic blue sheen. White underparts. Pink feet. White patches on wings appear as bar when folded. Caruncles absent. Voice During courtship displays, male barks and makes ticking sounds, female gives soft purr.

Distribution and population
Phalacrocorax colensoi is restricted to the Auckland Islands and adjacent waters, New Zealand. Colonies are present on Auckland, Enderby, Rose, Ewing and Adams Islands. The total breeding population has been estimated at fewer than 1,000 pairs (Robertson and Bell 1984). Surveys in 1988 and 1989 found 475 nests in 11 colonies on Enderby, one colony of 62 nests on Rose, and 306 nests on Ewing (Taylor 2000). A boat-based survey carried out in December 2011 counted 1,366 active nests on Enderby Island (J. Hiscock in litt. 2012). Its foraging range is assumed to be up to 24 km offshore (cf. New Zealand King Shag P. carunculatus).


Population justification
Although the population was thought to number fewer than 1,000 individuals, surveys in 1988 and 1989 indicated 475 nests in 11 colonies on Enderby, one colony of 62 nests on Rose, and 306 nests on Ewing. A boat-based survey of Enderby Island carried out in 2011 counted 1,366 active nests in 10 colonies (J. Hiscock in litt. 2012). Based on these data, a population of c.3,000 mature individuals is estimated, although a more up-to-date estimate of numbers in other colonies is needed (J. Hiscock in litt. 2012). On the basis of the estimated number of mature individuals, there are assumed to be c.4,500 individuals in total.

Trend justification
There are no new data, but the population is thought to be stable, following the elimination of most feral predators.

Ecology
It nests on the ground on ledges and the tops of steep cliffs. Sites are abandoned when sheltering plants are killed by guano, and waves sometimes destroy nests (Marchant and Higgins 1990). It feeds on small fish and marine invertebrates (Heather and Robertson 1997).

Threats
On Auckland Island, the major threat is from feral pigs which destroy any colony they can reach and, as a consequence, most, if not all, colonies are in inaccessible places (B. D. Bell in litt. 1994). On Rose and Enderby, feral cattle and rabbits may have had a similar impact and, on Enderby, cattle eliminated a tussock species that was a favoured nesting material (Taylor 2000). Cats are also potential predators on Auckland Island (G. A. Taylor in litt. 1994, Taylor 2000).

Conservation Actions Underway
In 1995, feral goats were eradicated from Auckland Island and, in 1993, feral cattle and rabbits were removed from Enderby and Rose (Taylor 2000). In 1998, the Auckland Islands group (already a nature reserve) was declared part of a World Heritage Site. In 2003, the area was designated as a Marine Reserve (B. Weeber in litt. 2003). Conservation Actions Proposed
Census the entire adult population once a suitable methodology has been developed, and on Auckland Island, survey coastline to locate all nesting sites. On Enderby, monitor the breeding population every 10 years. On Auckland Island, eradicate feral cats and pigs (Taylor 2000).

References
Heather, B. D.; Robertson, H. A. 1997. The field guide to the birds of New Zealand. Oxford University Press, Oxford, UK.

Marchant, S.; Higgins, P. J. 1990. Handbook of Australian, New Zealand and Antarctic birds, 1: ratites to ducks. Oxford University Press, Melbourne.

Robertson, C. J. R.; Bell, B. D. 1984. Seabird status and conservation in the New Zealand region. In: Croxall, J.P.; Evans, P.G.H.; Schreiber, R.W. (ed.), Status and conservation of the world's seabirds, pp. 573-586. International Council for Bird Preservation, Cambridge, U.K.

Taylor, G. A. 2000. Action plan for seabird conservation in New Zealand. Department of Conservation, Wellington.

Text account compilers
Benstead, P., Mahood, S., McClellan, R., Pilgrim, J., Taylor, J.

Contributors
Bell, B., Hiscock, J., Taylor, G., Weeber, B.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Phalacrocorax colensoi. Downloaded from http://www.birdlife.org on 19/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/04/2014.

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.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Auckland Islands shag (Phalacrocorax colensoi) 0

Key facts
Current IUCN Red List category Vulnerable
Family Phalacrocoracidae (Cormorants)
Species name author Buller, 1888
Population size 3000 mature individuals
Population trend Stable
Distribution size (breeding/resident) 17 km2
Country endemic? Yes
Links to further information
- Additional Information on this species