Justification of Red List Category
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.
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 in 10 colonies on Enderby Island (J. Hiscock in litt. 2012). Based on these data, a population of c.3,000 mature individuals is estimated, which roughly equates to c.4,500 individuals in total, although a more up-to-date estimate of numbers in other colonies is needed (J. Hiscock in litt. 2012).
Following the elimination of most feral predators, the population is thought to be stable.
Leucocarbo colensoi is restricted to the Auckland Islands and adjacent waters, New Zealand. Colonies are present on Auckland, Enderby, Rose, Ewing and Adams Islands. Its foraging range is assumed to be up to 24 km offshore (cf. New Zealand King Shag L. carunculatus).
It nests on the ground on ledges and the tops of steep cliffs. Sites are abandoned when sheltering plants are killed by guano. Waves sometimes destroy nests (Marchant and Higgins 1990). It feeds on small fish and marine invertebrates (Heather and Robertson 1997).
On Auckland Island, the major threat is from feral pigs which destroy any colony they can reach. As a consequence, most, if not all, colonies are in inaccessible places (B. D. Bell in litt. 1994). On Rose and Enderby Islands, feral cattle and rabbits may have had a similar impact and, on Enderby, cattle eliminated a tussock species which used to be 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. 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).
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.
Text account compilers
Fjagesund, T., Mahood, S., Benstead, P., Martin, R., McClellan, R., Miller, E., Pilgrim, J., Taylor, J.
Weeber, B., Bell, B., Taylor, G.A., Hiscock, J.
BirdLife International (2023) Species factsheet: Leucocarbo colensoi. Downloaded from http://www.birdlife.org on 31/03/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 31/03/2023.