Phalacrocorax colensoi 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Suliformes Phalacrocoracidae

Scientific Name: Phalacrocorax colensoi Buller, 1888
Common Name(s):
English Auckland Shag, Auckland Island Shag
Leucocarbo colensoi ssp. colensoi (Buller, 1888) — 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, 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.

Assessment Information [top]

Red List Category & Criteria: Vulnerable D2 ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Bell, B., Hiscock, J., Taylor, G.A. & Weeber, B.
Facilitator/Compiler(s): Benstead, P., Mahood, S., McClellan, R., Pilgrim, J., Taylor, J.
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.

Previously published Red List assessments:

Geographic Range [top]

Range Description: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).

Countries occurrence:
New Zealand
Additional data:
Estimated area of occupancy (AOO) - km2:17Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:5900
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:5Continuing 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: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.

Current Population Trend:Stable
Additional data:
Number of mature individuals:3000Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:5Continuing 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 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).

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): 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 [top]

Conservation Actions: 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).

Citation: BirdLife International. 2016. Phalacrocorax colensoi. The IUCN Red List of Threatened Species 2016: e.T22696869A93590409. . Downloaded on 23 April 2018.
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