Species Profile and Threats Database

For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Vulnerable as Leucocarbo atriceps nivalis
Listed marine as Phalacrocorax nivalis
Recovery Plan Decision Recovery Plan required, this species had a recovery plan in force at the time the legislation provided for the Minister to decide whether or not to have a recovery plan (19/2/2007).
Adopted/Made Recovery Plans National Recovery Plan for Ten Species of Seabirds 2005-2010 (Department of the Environment and Heritage (DEH), 2005f) [Recovery Plan] as Leucocarbo atriceps nivalis.
Other EPBC Act Plans Threat abatement plan to reduce the impacts of exotic rodents on biodiversity on Australian offshore islands of less than 100 000 hectares 2009 (Department of the Environment, Water, Heritage and the Arts (DEWHA), 2009u) [Threat Abatement Plan].
Policy Statements and Guidelines Issues Paper: Population status and threats to ten seabird species listed as threatened under the Environment Protection and Biodiversity Conservation Act 1999 (Department of the Environment and Heritage (DEH), 2005p) [Admin Guideline].
Survey Guidelines for Australia's Threatened Birds. EPBC Act survey guidelines 6.2 (Department of the Environment, Water, Heritage and the Arts (DEWHA), 2010l) [Admin Guideline].
Federal Register of
    Legislative Instruments
Declaration under s178, s181, and s183 of the Environment Protection and Biodiversity Conservation Act 1999 - List of threatened species, List of threatened ecological communities and List of threatening processes (Commonwealth of Australia, 2000) [Legislative Instrument] as Phalacrocorax nivalis.
Declaration under section 248 of the Environment Protection and Biodiversity Conservation Act 1999 - List of Marine Species (Commonwealth of Australia, 2000c) [Legislative Instrument] as Phalacrocorax nivalis.
Amendment to the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (11/04/2007) (Commonwealth of Australia, 2007f) [Legislative Instrument] as Leucocarbo atriceps nivalis.
Scientific name Leucocarbo atriceps nivalis [66994]
Family Phalacrocoracidae:Pelecaniformes:Aves:Chordata:Animalia
Species author Falla, 1937
Infraspecies author  
Other names Phalacrocorax nivalis [64446]
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images

Scientific name: Leucocarbo atriceps nivalis

Common name: Imperial Shag (Heard Island)

Other names: Heard Shag, Heard Island Cormorant, Blue-eyed Cormorant, Imperial Cormorant, Blue-eyed Shag
Cormorants and shags are distinctive aquatic birds typically breeding on both mainland and island sites. Those that are restricted to remote islands are typically sedentary. Recent reviews of the taxonomy have resulted in the recognition at the specific level of several forms restricted to particular islands (Shirihai 2002). The Imperial Shag (Heard Island) represents such forms and has been the subject of several studies (Brothers 1985, Green 1997a, b; Green & Williams 1997).

The taxonomy of the Imperial Shag (Heard Island) is complex and remains disputed (Green et al. 1990; Green 1997a). Some authors recognised eight subspecies of Leucocarbo atriceps (Christidis & Boles 1994; Harrison 1983; Sibley & Monroe 1990) whilst others (Marchant & Higgins 1990) recognise eight distinct species, with L. atriceps nivalis restricted to Heard Island. Others considered the Imperial Shag (L. atriceps) group to comprise multiple subspecies, including L. atriceps nivalis (BirdLife International 2004e; Turbott 1990). Such a treatment consequently results in the Least Concern rating by BirdLife International (2004e).

This profile treats the Imperial Shag (Heard Island) as a subspecies.

The Imperial Shag (Heard Island) is a medium-sized, black and white marine shag. The adult form reaches a length of 77 cm with a wingspan of 120 cm and weighs 3kg. Sexes are alike and undergo seasonal plumage changes when not breeding, including; the absence of crest and plumes, dull/faded dorsal plumage and soft parts, and yellow caruncles (Marchant & Higgins 1990).

Adult breeding birds have a glossy black top and sides of head and hindneck with a black recurved crest on the forehead. There is a varying amount of white filoplumes in tuft above and behind the eye and scattered elsewhere on the head, neck and back. The upper wing-coverts are a blackish brown with a green sheen. The alar (underside of the wing) is white. The back is black with patches of white between the posterior bases of the wings; the rump is black and the tail is black with white shaft bases. The underparts are white while the underwings are black with a white axillary line. The bill is grey with a horn colored patch near the tip of the lower mandible and a prominent pair of orange caruncles above the base of the bill in front of the eye. The eye ring is blue and the iris is dark brown. Legs and feet are a bright pink (Marchant & Higgins 1990).

Juveniles are distinguished from adults as they are predominately brown with a green sheen above and are white ventrally. The alar is a brown patch varying in extent. Juveniles do not have caruncles or bright eye-rings (Marchant & Higgins 1990).

The Imperial Shag (Heard Island) is restricted to breeding in approximately four colonies at Heard Island in the Southern Ocean. The four colonies include: Cape Pillar, Stephenson Lagoon, Saddle Point and at Sydney Cove (Woehler 2000). There are no breeding records or observations from the McDonald Islands (Johnstone 1982; Marchant & Higgins 1990; Vining 1983).

The Imperial Shag (Heard Island) is sedentary, making only local movements around their respective islands. Brothers (1985) reported that they are poor fliers, unable to make headway in strong winds (> 40 knots), and their morphology (small wings, heavy bones and water permeable plumage) restricted long range movements.

The extent of occurrence is estimated at 60 km² with high reliability (Garnet & Crowley 2000).

The area of occupancy is estimated at 3 km² with high reliability (Garnet & Crowley 2000).

Colony sites of the Imperial Shag (Heard Island) are well known and monitored by the Australian Antarctic Division. Three of the four are readily accessible, but the remoteness of the Cape Pillar colony prevents regular island-wide censuses (E. Woehler 2002, pers. comm).

Trends in the population size of the Imperial Shag (Heard Island) are uncertain because there have been infrequent censuses and incomplete coverage of Heard Island during counts. The population census during the 2000 to 2001 season was the first count of the entire population of this species (E.J. Woehler 2002, pers. comm).

Until recently, the total breeding population of the Imperial Shag (Heard Island) was estimated to be between 100 and 200 pairs known from three colonies at Sydney Cove, Saddle Point and Stephenson Lagoon (Green 1997b). Roosting sites are more widespread and numerous (Pemberton & Gales 1987). In November 2001, a large colony of approximately 1000 pairs on three terraces adjacent to a large Macaroni Penguin Eudyptes chrysolophus colony at Cape Pillar was discovered.

Woehler (undated) estimates the total breeding population is estimated at approximately 1220 adult pairs for the 2000/01 summer , distributed between the following four colonies:

  • Cape Pillar, around 1000 pairs
  • Stephenson Lagoon, around 100 pairs
  • Saddle Point, around 80 pairs
  • Sydney Cove, around 30 pairs (Woehler 2000).

The population size of the Heard Shag is thought to naturally fluctuate. The maximum numbers of chicks fledged in 1986, 1987 and 1988 were 43, seven and 94 respectively. The maximum number of birds at the main roost sites at Stephenson Lagoon varied from 548 to 127 between 1985 and 1988 (K. Green, as cited in Marchant & Higgins 1990).

Absence of comparable longitudinal data preclude assessment of population trends for the Imperial Shag (Heard Island). Further systematic surveys are required to confidently assess trends.

The Imperial Shag (Heard Island) is a marine bird. It forages inshore in coastal shallows, and there are no records of the species away from Heard Island (Marchant & Higgins 1990).

The species breeds on sea-facing cliff tops on offshore vegetated stacks (50 m offshore) and at the edge of weathered lava cliffs, in tussock grassland among tussocks of the grass Poa cookii and the moss Azorella sp. (E.J. Woehler 2002, pers. comm; Marchant & Higgins 1990). One breeding colony is situated on flat ground, and the others are on steep vegetated slopes or cliffs (Green 1997a). At Cape Pillar, the Imperial Shag (Heard Island) breeding colony is on the edge of a very large (around 25 000 pairs) Macaroni Penguin Eudyptes chrysolophus colony near the coast (Woehler 2000).

Roosting sites of the Imperial Shag (Heard Island) are more widely distributed than breeding sites. The species roosts on cliff-tops, offshore stacks, cobbles on beaches, sandy beaches and areas of volcanic sand on headlands (E.J. Woehler 2002, pers. comm; Green 1997a; Marchant & Higgins 1990)

The Imperial Shag (Heard Island) is a sedentary species that breed in colonies and is gregarious at roost sites and when feeding. Nests typically comprise a truncated column structure composed of mud, guano and vegetation. A clutch of one to three blue-green eggs is laid in October-November (Brothers 1985).

The timing of egg laying for Heard Shags can vary widely, with the earliest eggs being laid from mid September and the latest mid November; this liability in breeding season is interpreted as an adaptation to exploit periods of high food availability (Burton, H.R. & D.L. Williams, as cited in Marchant & Higgins 1990; Green 1997b). Most laying probably occurs during the last half of October (Marchant & Higgins 1990). Chicks generally hatch in November and early December. They fledge and depart the colony between January and February (Green 1997b).

Records of breeding success in the Imperial Shag (Heard Island) are:

  • In the 1985 to 1986 season, a maximum of 43 Imperial Shag (Heard Island) chicks may have fledged from a maximum of 90 nests.
  • In the 1986 to 1987 season, a maximum of 27 attended nests could have fledged only seven chicks.
  • At Sydney Cove (20th December 1987) 24 chicks fledged from 18 nests.
  • At Saddle Point (10th October 1987) there were 76 nests, and on the 4th of February 1988, 70 chicks (Woehler, E.J. in Marchant & Higgins 1990).
  • In the 1992 to 1993 season at Stephenson Lagoon, 82 chicks fledged from 140 eggs laid (58.6%); there were 1.88 to 1.89 chicks reared (to 55 days old) per nest (Green 1997b).
  • For unknown reasons, breeding success in the 1992 to 1993 season varied depending on which side of the moraine birds nested; 25% fledged on the eastern side and 62% on the western side (Green 1997b).
  • In the 2000 to 2001 season at Saddle Point, 39 nests produced one chick.
  • In the 2000 to 2001 season at Stephenson Lagoon, 98 nests produced one chick (E.J. Woehler 2002, pers. comm).
Breeding success is problematic to assess, given the young birds' habit of moving from their nests before becoming fully independent of parents. A breeding success rate of 59% has been observed for Imperial Shags (Heard Island), where nests produced an average of 1.9 chicks per nest (Green 1997b).

There are no data on adult or juvenile survival rates for the Imperial Shag (Heard Island), the mobility of birds among colonies making such assessments difficult (Brothers 1985).

The diet of the Imperial Shag (Heard Island) consists mainly of polychaetes (marine worms) and fish, and occasionally includes squid and other molluscs (Green & Williams 1997; Marchant & Higgins 1990). The diet of adults varies according to site (Green et al. 1990) and especially season. In the non-breeding season Shags eat mostly polychaetes, but in the breeding season they feed fish to their young, particularly notothenioids (icefishes) (Green & Williams 1997). At Stephenson Lagoon (a roost site), polychaetes were in 100% of samples (of 400 casts), fish in 21.6% and molluscs (gastropods) in 0.9%. At breeding sites, polychaetes were in 96 to 97% of samples (of 42), fish in 100% and there were also some molluscs present (gastropods and octopods) (Marchant & Higgins 1990).

Species of fish eaten by Imperial Shags (Heard Island) include Notothenia acuta, N. cyanobrancha, N. rossii, N. squamifrons, Paranotothenia magellanica, Notolepis spp., Muraenolepis spp., Zanchlorhynchus spinifer, Nototheniops mizops, Harpagifer spp., and Channichthys rhinoceratus (Green et al. 1990; Green & Williams 1997; Marchant & Higgins 1990). Algae has also been recorded in the diet (Marchant & Higgins 1990).

Imperial Shags (Heard Island) hunt by pursuit diving to a depth of up to 60 m, but usually to depths of less than 5 m. Compared with other shag species, Imperial Shags (Heard Island) appear to perform shorter and shallower dives, suggesting that adequate food is available in shallow waters around the island. They feed in inshore waters (Green & Williams 1997).

Local movements of the Imperial Shag (Heard Island) are confined to Heard Island (Marchant & Higgins 1990). Non-breeding birds move each day from roosting sites at Stephenson Lagoon to feed in shallow waters off Elephant Spit at the eastern end of Heard Island (Green 1997a).

In mid February, adults and juveniles move from breeding sites on the northwest coast to roosts in the southeast, especially Stephenson Lagoon (K. Green, as cited in Marchant & Higgins 1990). The exact date of their return to breeding colonies has not been recorded (Marchant & Higgins 1990), but nest construction begins in May (Green 1997b). It is likely that Imperial Shags (Heard Island) attend colonies during the winter months (E.J. Woehler 2002, pers. comm).

The Imperial Shag (Heard Island) nests in colonies that consist of around 30 to 1000 pairs of birds (Marchant & Higgins 1990; Woehler 2000). The population density of this species has not been measured, but appears to vary with habitat (E.J. Woehler, as cited in Marchant & Higgins 1990). The greatest density of nests is on the flat coastal terrace at Cape Pillar (E.J. Woehler 2002, pers. comm).

There are no other species on Heard Island that are similar to the Imperial Shag (Heard Island). Elsewhere, birds that resemble the Imperial Shag (Heard Island) include Antarctic Shags P. bransfieldensis and Kerguelen Shags P. verrucosus and all blue-eyed cormorants that have sometimes been considered to be one species, the Imperial Shag, Leucocarbo atriceps, together with the Imperial Shag (Heard Island) (Marchant & Higgins 1990).

The Imperial Shag (Heard Island) is endemic to a single island, and so the species is susceptible to chance events (E.J. Woehler 2002, pers. comm.).

The Imperial Shag (Heard Island) is considered threatened because the populations are small and restricted in distribution. As a result, the birds could be adversely affected by effects of climate change on sea temperature and food supply (Garnett & Crowley 2000), in addition to other threats that affect small and vulnerable species of seabirds, such as marine pollution and marine debris.

Heard Island is predator free, so that the threat that may be posed by feral pests remains absent on this island (Schulz & Lynn 2003).

Severe weather conditions are likely contribute more than any other factor to mortality of the Imperial Shag (Heard Island), with fluctuations in breeding success being attributed to frequently inclement weather (Pemberton & Gales 1987). The effects of adverse weather on breeding success may be manifested not only by physical destruction of nests but also by restricting access to available prey.

Human mediated deaths have also been recorded for the Imperial Shag (Heard Island), with fatal strikes with radio masts being recorded around Heard Island (Brothers 1985, Green 1997). The shallow and inshore foraging behavior of the Shags makes them unlikely candidates for interactions with commercial fishing operations around Heard Island. A total prohibition on commercial fishing within 13 nautical miles of Heard Island likely minimises against potential interactions with the Shags. It is possible that commercial fishing in the Southern Ocean region could affect the birds' food supply (Garnett & Crowley 2000; Marchant & Higgins 1990).

One Imperial Shag (Heard Island) was found dead after flying into a radio mast (Green 1997b), and birds may be at risk from striking wind-turbines (E.J. Woehler 2002, pers. comm).

The following threat abatement recommendations are outlined in the Issues Paper: Population status and threats to ten seabird species listed as threatened under the Environment Protection and Biodiversity Conservation Act 1999 (DEH 2005p).

  • Complete surveys of Imperial Shag (Heard Island) populations to be undertaken when possible in order to assess population status.
  • Ensure effective quarantine programs at all breeding sites to minimise introduction of pests.
  • Where possible long radio and HF dipole aerials should be replaced by whip aerials to reduce the incidental morality caused by bird strike.
  • All colonies to be protected and managed in such a way that human disturbance is minimised.
  • Maintain current prohibitions of fishing in waters immediately adjacent to the breeding islands.

The Action Plan for Australian Birds and the Issues Paper: Population status and threats to ten seabird species listed as threatened under the Environment Protection and Biodiversity Conservation Act 1999 provide guides to threat abatement and management strategies for the Imperial Shag (Heard Island) (DEH 2005p; Garnett & Crowley 2000).

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Biological Resource Use:Fishing and Harvesting Aquatic Resources:Commercial harvest Leucocarbo atriceps nivalis in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage (DEH), 2006ne) [Internet].
Climate Change and Severe Weather:Climate Change and Severe Weather:Climate change altering atmosphere/hydrosphere temperatures, rainfall patterns and/or frequency of severe weather events Leucocarbo atriceps nivalis in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage (DEH), 2006ne) [Internet].
Ecosystem/Community Stresses:Indirect Ecosystem Effects:Restricted geographical distribution (area of occupancy and extent of occurrence) Leucocarbo atriceps nivalis in Species Profile and Threats (SPRAT) database (Department of the Environment and Heritage (DEH), 2006ne) [Internet].

BirdLife International (2004e). Threatened birds of the world 2004. Cambridge, U.K: BirdLife International.

Brothers, N. (1985). Breeding biology, diet and morphometrics of the King Shag, Phalacrocorax albiventer purpurascens at Macquarie Island. Australian Wildlife Research. 12:81--94.

Christidis, L. & W.E. Boles (1994). The Taxonomy and Species of Birds of Australia and its Territories. Royal Australasian Ornithologists Union Monograph 2. Melbourne, Victoria: Royal Australasian Ornithologists Union.

Department of the Environment and Heritage (DEH) (2005f). National Recovery Plan for Ten Species of Seabirds 2005-2010. [Online]. Available from:

Department of the Environment and Heritage (DEH) (2005p). Issues Paper: Population status and threats to ten seabird species listed as threatened under the Environment Protection and Biodiversity Conservation Act 1999. [Online]. Available from: [Accessed: 11-Apr-2008].

Garnett, S.T. & G.M. Crowley (2000). The Action Plan for Australian Birds 2000. [Online]. Canberra, ACT: Environment Australia and Birds Australia. Available from:

Green, K. (1997a). Biology of the Heard Island Shag Phalacrocorax nivalis. 1. Breeding behaviour. Emu. 97:60-66.

Green, K. (1997b). Biology of the Heard Island Shag Phalacrocorax nivalis. 2. Breeding. Emu. 97:67-75.

Green, K. & R. Williams (1997). Biology of the Heard Island Shag Phalacrocorax nivalis. 3. Foraging, diet and diving behaviour. Emu. 97:76--93.

Green, K., R. Williams, E.J. Woehler, H.R. Burton, N.J. Gales & R.T. Jones (1990). Diet of the Heard Island Cormorant Phalacrocorax atriceps nivalis. Antarctic Science. 2:139--141.

Harrison, P (1983). Seabirds: An Identification Guide. London: Croom Helm.

Johnstone, G.W. (1982). Expedition to the Australian Territory of Heard and McDonald Islands 1980. Veenstra, C. and J. Manning, eds. Zoology. Page(s) 33-39. Division of National Mapping, Technical Report 31, Canberra.

Magrath, M.J.L., M.A. Weston, P. Olsen & M. Antos (2004). Draft Survey Standards for Birds: Species Accounts. Melbourne, Victoria: Report for the Department of the Environment and Heritage by Birds Australia.

Marchant, S. & P.J. Higgins, eds. (1990). Handbook of Australian, New Zealand and Antarctic Birds. Volume One - Ratites to Ducks. Melbourne, Victoria: Oxford University Press.

Pemberton, D. & R. Gales (1987). Notes on the status and breeding of the Imperial , Phalacrocorax atriceps at Heard Island. Cormorant. 15:33-40.

Schulz, M. & Lynn, J (2003). Burrowing petrels on Macquarie Island, late March to early December 2003. Report to Nature Conservation Branch, Department of Primary Industries, Water and Environment, Hobart, Tasmania. Department of Primary Industries, Water and Environment, Hobart, Tasmania.

Shirihai, H. (2002). The Complete Guide to Antarctic Wildlife. Princeton & Oxford: Princeton University Press.

Sibley, C.G. & B.L. Monroe (1990). Distribution and Taxonomy of the Birds of the World. New Haven, Connecticut: Yale University Press.

Turbott, E.G. (1990). Checklist of the birds of New Zealand and the Ross Dependency, Antarctica. Random Century, Auckland.

Vining, R. (1983). Heard Island 1983 Scientific Reports. Garvan Institute of Medical Research, Sydney.

Woehler, E.J. (2000). Stop press: major seabird discovery at Heard Island. Australasian Seabird Bulletin. 37:36.

Woehler, E.J. (2002). Personal communication.

Woehler, E.J. (undated). Status and conservation of the seabirds of Heard Island. Green, K. & E.J. Woehler, eds. Heard Island: Southern Ocean Sentinel. Surrey Beatty, Sydney.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Leucocarbo atriceps nivalis in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: Accessed Wed, 17 Sep 2014 15:50:49 +1000.