Phalacrocorax chalconotus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Suliformes Phalacrocoracidae

Scientific Name: Phalacrocorax chalconotus (Gray, 1845)
Common Name(s):
English Stewart Shag, Bronzed Shag, Bronze Shag
Spanish Cormorán de la Stewart
Leucocarbo chalconotus ssp. chalconotus (Gray, 1845) — Turbott (1990)
Taxonomic Source(s): Turbott, E.G. 1990. Checklist of the Birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Identification information: 68 cm. Large cormorant with pied and bronze phases. Pied phase, blackish head, upperparts with white patch on upperwings appearing as a bar when folded. White underparts. Pink feet. Orange caruncles. Bronze phase, all brownish-black with green-blue sheen. Voice Male calls at nest, silent away from colonies.

Assessment Information [top]

Red List Category & Criteria: Vulnerable C2a(i) ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Lalas, C., Taylor, G.A. & Weeber, B.
Facilitator/Compiler(s): Benstead, P., Mahood, S., McClellan, R., Moreno, R., Pilgrim, J., Taylor, J., Wanless, R., van der Merwe, N.
This species is classified as Vulnerable because it has a small range and is restricted to a small and decreasing number of colonies. Although it is known to abandon and reoccupy sites over decades, the loss of a comparatively large number of locations in recent years is of concern, and although population trends are unclear, the population may be declining.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Phalacrocorax chalconotus is endemic to New Zealand, breeding on the South Island from the coast of North Otago south to Foveaux Strait, and on Stewart Island. In total, it breeds at c.9 localities (G. A. Taylor in litt. 2000), in colonies of 10-500 pairs (Heather and Robertson 1997). Individual island population estimates from the 1950s-1970s indicate a total of c.3,000 birds (Marchant and Higgins 1990). The only national census dates from 1981, and estimated the population at 1,800-2,000 breeding pairs, 900-1,000 in both Otago and Southland. The Otago population doubled to 1,850 pairs in 1987-1988, and the breeding range also expanded, but numbers then decreased to 1,500 pairs in 1992-1993 (Taylor 2000). Total numbers may be as high as 5,000-8,000 (C. Lalas in litt. 1994). In 1914, the population on Kane-te-toe Island was estimated at 400-500 nests; however, by 1975 the colony had been deserted (Watt 1975). The population on Centre Island declined from 600 to 25 nests between 1955 and 1991 (Taylor 2000). Colonies on Jacky Lee and Codfish Islands have also been deserted (B. Weeber in litt. 2000). It disperses over shallow inshore waters within 15 km of land (G. A. Taylor in litt. 2000).

Countries occurrence:
New Zealand
Additional data:
Estimated area of occupancy (AOO) - km2:45Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:52900
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:13Continuing decline in number of locations:Yes
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Population estimates have varied, although the population may be as high as 5,000-8,000 individuals (C. Lalas in litt. 1994). This is roughly equivalent to 3,300-5,300 mature individuals.

Trend Justification:  Although there are no new data on the population size, it is suspected to be declining overall, as the colony at Centre Island has declined dramatically (Taylor 2000), and colonies on the islands of Jacky Lee and Codfish have been deserted (B. Weeber in litt. 2000).

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:1800Continuing 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

Habitat and Ecology [top]

Habitat and Ecology:It breeds on rocky headlands and islands, building a platform nest of twigs, seaweed and guano, 0.5 m in diameter and 1-1.5 m high (Marchant and Higgins 1990, Heather and Robertson 1997). It appears to eventually destroy the surrounding vegetation, probably contributing to the abandonment of colonies until sufficient regeneration has occurred (Watt 1975). It feeds on fish and marine invertebrates (Heather and Robertson 1997).

Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):8.7
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): Human activities very easily disturb colonies and may have caused the desertion of some in the past (Watt 1975). Illegal shooting is a problem (Heather and Robertson 1997). Set-nets are a major threat, regularly catching birds, particularly near breeding colonies. Introduced predators such as mustelids Mustela spp., cats and rodents are a threat to mainland colonies (Taylor 2000).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
Although only one national census has been completed, many counts have been made at individual colonies, mostly since the 1950s (Taylor 2000).

Conservation Actions Proposed
Survey the species's entire range to locate and census all breeding colonies. Monitor at least one colony in Otago and Foveaux Strait yearly, and census the entire breeding population every 10 years. Develop techniques to establish new colonies. Fence colonies at mainland sites to exclude predators and stock. Develop an advocacy programme to discourage shooting and encourage the safe use of set-nets in order to minimise bycatch, enforcing restrictions if necessary, near Stewart Island colonies (Taylor 2000). Prevent marine farming near breeding colonies and feeding areas (B. Weeber in litt. 2000). Obtain legal protection for all colonies (Taylor 2000). All sites for present colonies of Stewart Island shag have been proposed as an IBA (Hand, 2013).

Citation: BirdLife International. 2016. Phalacrocorax chalconotus. The IUCN Red List of Threatened Species 2016: e.T22696853A93589619. . Downloaded on 22 June 2018.
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