88Wildlife Conservation Plan for Seabirds

88 Wildlife Conservation Plan for Seabirds

Kerguelen Petrel (Lugensa brevirostris)

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TABLE Species information for the Kerguelen Petrel (Lugensa brevirostris)

The Kerguelen Petrel (Lugensa brevirostris also known as Aphrodroma brevirostris) is a medium-sized all-dark petrel of the Southern Ocean, similar in size to Soft-plumaged Petrel (Pterodroma mollis). The species has a very large circumpolar range in subantarctic and Antarctic waters. Kerguelen Petrel breeding colonies are present on Gough Island (St Helena to UK) in the Atlantic Ocean, and Marion Island and Prince Edward Island (South Africa), and Crozet Islands and Kerguelen Island (French Southern Territories) in the Indian Ocean. Its breeding season starts in August, forming loose colonies near the sea on marshy ground, and also higher up on volcanic ridges up to 450 m Above Sea Level (ASL). It nests in deep burrows dug in soft, wet soil (del Hoyo et al. 1992). Outside the breeding season its range is circumpolar, frequenting Australian waters south to the ice pack (del Hoyo et al. 1992). It feeds mostly on squid, but also krill and fish. Squid are captured by surface-seizing at night, but dipping is also seen.

Brooke (2004) estimated that the global population numbers around 1 million individuals. The population is suspected to be decreasing, as invasive House Mice (Mus musculus) may be affecting breeding success.

On Gough Island, one of the locations where this species is known to breed, mice are responsible for reduced breeding success of burrowing petrel species (Cuthbert et al. 2013). While the effects on this species specifically have not been investigated it is also likely to be negatively affected.

White-headed Petrel (Pterodroma lessonii)

TABLE Species information for the White-headed Petrel (Pterodroma lessonii)

The White-headed Petrel (Pterodroma lessonii) is a large, solidly built all grey-white petrel. At sea the prominent black patch underscoring eye on an otherwise largely white head is diagnostic. The White-headed Petrel is oceanic, rarely approaching land except near colonies, but has been recorded inshore during stormy weather. This species has a circumpolar range and is found throughout the Southern Ocean. It breeds on Macquarie Island, the Auckland Islands and Antipodes Islands (New Zealand), Crozet and Kerguelen Islands (French Southern Territories) and possibly on the Prince Edward Islands (South Africa) (del Hoyo et al. 1992). Breeding starts in October in loose colonies, nesting in burrows dug in soft soil or scree near the coast or inland up to 300 m Above Sea Level (ASL) (del Hoyo et al. 1992). The distribution extends farther north in the non-breeding season. Birds feed mostly on squid and crustaceans, which are caught mostly at night by surface-seizing and dipping.

Brooke (2004) estimated the global population to number around 600,000 individuals. In 1975-79, the breeding population on Macquarie Island was estimated to be around 16,000 breeding pairs (Brothers 1984). The most recent island population census was undertaken in 2018, with results pending (University of Queensland and Tasmanian Parks and Wildlife Service unpublished data). The global population is thought to be decreasing owing to predation by invasive species at some sites. Trends in Australia are unknown.

The primary threats to this species come from invasive predators. Extinction of the species on Auckland Island, New Zealand is attributed to the impact of introduced pigs and cats (Taylor 2013), and despite large numbers breeding birds adjacent to the main island the continued presence of both pigs and cats prevents any recolonisation effort. Cats, Black Rats, European Rabbits and Weka are thought to have caused decreases on Macquarie Island before their eradication (Taylor 2013). The breeding population on Macquarie Island is expected to increase following the removal of invasive species.

 Consolidate current population data on Macquarie Island

 Implement best practice quarantine measures at breeding colonies to reduce the risk of any invasive species (re)establishing on islands