Auckland Islands Shag Leucocarbo colensoi Scientific name definitions

63 cm; c. 2000 g; wingspan 105 cm. Adult has rather long crest  on crown, head and upperparts black with bluish gloss, greener on head  , can have a few scattered hair-like white plumes at least on head, less bright, more brownish and bronzy green on upperwing  , sometimes with white on scapulars, male can have central white dorsal patch, and there is usually variable white bar on median wing-coverts; underwing blackish, blacker on marginal to median coverts, can have some white at base of leading edge; tail duller blackish; white chin to undertail-coverts , narrow on foreneck, and black of sides can meet on lower throat or on central foreneck; non-breeder marginally duller, lacks white filoplumes and has crest much reduced or lacking; iris dark greenish grey. Bare facial skin  over most of face reddish fuscous, externallink violet to magenta, warty yellow line at base of maxilla, orange-red to dusky red bare skin below gape and on gular pouch  , while non-breeder has skin below gape and gular pouch much duskier, eyering also duller; bill blackish grey to dark brownish grey with subterminal paler horn-coloured spot or band, and horn-yellow base to mandible; legs mostly pale pink with variable dark greyish tones. Sexes similar. Juvenile has only hint of crest, is dusky grey-brown (not black), several median and lesser wing-coverts are fringed paler brown, wing-coverts and remiges more pointed than adult’s, small whitish feathers on lores, iris brownish grey, eyering and skin around bill much duller; subsequent plumage  can appear spotted given combination of brown (bleached and worn) juvenile feathers and blackish-brown newer ones, while white feathers appear on upper foreneck. Similar to L. ranfurlyi in general pattern, some with more black on neck, and adults distinguished by less plain, more contrastingly-coloured facial skin with unique eyering and well-defined yellow at bill-base, and bill usually appears slightly shorter. Face pattern most similar to L. campbelli except eyering, and rarely has as much black at base of foreneck; differs from L. chalconotus in pattern of neck and facial skin; from L. onslowi and other pied shags with extensive black on face by lack of caruncles; those with black on foreneck may recall much more slender L. bougainvilliorum and structurally more similar L. magellanicus, from which differs in pattern of facial skin and usually in having white bar on upperwing.

Sometimes placed in Phalacrocorax or Euleucocarbo, but classification here follows results of a comprehensive molecular phylogeny for the entire family (1 Kennedy, M. and Spencer, H.G. (2014). Classification of the cormorants of the world. Molecular Phylogenetics and Evolution. 79: 249–257. Close ). In past, often considered a race of L. campbelli (which see). Monotypic.

Restricted to Auckland Is (S of New Zealand), breeding at Auckland, Enderby, Rose, Ewing and Adams.

Marine. Forages equally in open sea or in sheltered coastal waters, including bays or inlets. Breeds  and roosts on ledges, on tops of sea cliffs or in hollows; also on flat ground among grass tussocks or in shelter of overhanging rocks, bushes or trees.

Sedentary. A juvenile first seen at Snares Is (N of Auckland Group) in Jul 1994 had gained adult plumage by Mar 1996, and still present in Oct 2000, when it defended a nest-site in penguin colony; what was presumably same individual seen also in Jan and Feb 2001 (2 Miskelly, C. M., Sagar, P. M., Tennyson, A. J. D. and Scofield, R. P. (2001). Correction: Leucocarbo shag at the Snares Islands. Notornis. 48(3): 185. Close ). Otherwise, no records far from Auckland Is.

Little known. Small octopus (Octopus sp.) accounted for 57% of prey by number and 68% of prey by wet mass in 23 regurgitated pellets collected in Aug; only two other genera contributed > 5% towards the total mass of prey, red cod (Pseudophycis bachus) and triplefin (Forsterygion sp.) (3 Lalas, C. and McConnell, H. (2012). Prey of Auckland Island shags (Leucocarbo colensoi) in winter. Notornis. 59(3-4): 130–137. Close ). Probably also crustaceans and other small fish. Presumably feeds mainly by pursuit-diving. Sometimes forms large feeding flocks.

Male advertises with rough barking “borr” or “orr-orrgh”, threatens with “erh-erh-erh”; various other calls include drawn-out “owhrr” when hopping, and accelerating “gok-gok-gok” when regurgitating pellets. Female gives soft calls.

Laying Nov–Feb. Forms small or large monospecific colonies  . Nest mainly of tussock grass  , also seaweed, twigs, peat and debris, placed on ledge or cliff top  or on ground among tussocks. Clutch apparently normally three eggs; incubation period 26–32 days; chicks naked, grow grey down  ; brood normally consists of two chicks  .

VULNERABLE. Restricted to Auckland Is and adjacent waters. Breeding colonies exist on islands of Auckland, Enderby, Rose, Ewing and Adams. According to BirdLife, estimated global breeding population c. 3000 mature individuals; in surveys in 1988 and 1989, 475 nests found in 11 colonies on Enderby, single colony of 62 nests on Rose, and 306 nests on Ewing; in boat-based survey in Dec 2011, 1366 active nests counted in ten colonies on Enderby I. Total population, including non-breeders, put at c. 4500 individuals. Believed to be reasonably stable. Nests sometimes washed away by high tides or storm waves. On Auckland I, main threat  from feral pigs, which destroy any colony which they can reach (consequently, most or all colonies now in inaccessible sites); in the past entire colonies were destroyed by pigs (4 Flux, I. A. (2002). New Zealand white-capped mollymawk (Diomedea cauta steadi) chicks eaten by pigs (Sus scrofa). Notornis. 49(3): 175-176. Close ). Cats also potential predators on Auckland. On Rose and Enderby, feral cattle and rabbits may have had destructive impact; on Enderby, cattle eliminated a tussock species that was favoured by this shag as nesting material. In 1995, feral goats eradicated from Auckland I, and in 1993 feral cattle and rabbits removed from Enderby and Rose. In 1998, Auckland group (already a nature reserve) was declared part of a World Heritage Site; in 2003, area designated as Marine Reserve.