90Wildlife Conservation Plan for Seabirds

90 Wildlife Conservation Plan for Seabirds

Great-winged Petrel (Pterodroma macroptera)

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TABLE Species information on the Great-winged Petrel

The Great-winged Petrel (Pterodroma macroptera) is a large, long winged gadfly petrel with all-dark plumage and black bill, that is very similar to Grey-faced (P. gouldi) and Providence (P. solandri) Petrels. Until recently Grey-faced Petrel and Great-winged Petrel were considered conspecific, it was not until 2014 that these two species were considered as different species (Wood et. al. 2016). The species has a widespread, but sparse distribution. It breeds in the Southern Hemisphere with colonies on Tristan da Cunha and Gough Island (St Helena to UK), the Crozet Islands and Kerguelen Islands (French Southern Territories), the Prince Edward Islands (South Africa), and on the coasts of south-western Australia. Breeding occurs in the winter, arriving at colonies in April. It nests either solitary or in small colonies on oceanic islands on ridges, slopes or flat ground. Breeding usually occurs below 400 m Above Sea Level (ASL) but has been recorded as high as 1,400 m ASL on Tristan da Cunha. It nests in burrows or above ground in rock crevices, among tree roots or under scrub (del Hoyo et al. 1992). Outside the breeding season, it disperses widely in subtropical parts of the Atlantic, Indian and Pacific Oceans (del Hoyo et al. 1992). It feeds mostly on squid, with some fish and crustaceans, most of which it obtains by dipping and surface-seizing. It feeds mainly at night and may locate some cephalopods by their bioluminescence. It can occasionally be seen following cetaceans and will associate with other petrels and shearwaters. Occasionally follows vessels.

Brooke (2004) estimated the global population to exceed 1,500,000 individuals. The Australian breeding population is restricted to 17 offshore islands in south-west Western Australia. The minimum estimated number of breeding pairs is 36,000–84,000 (Burbidge et al. 1996). Trends in Australia are unknown. The global population is suspected to be decreasing owing to predation by invasive species.

This species has experienced decreases due to invasive predatory mammals. Cats caused a decrease in the species on Marion Island before their eradication in 1991 (Cooper et al. 1995). Despite cat eradication, subsequent recovery on Marion has been slower than expected, possibly due to breeding success remaining unexpectedly low. This has been attributed to the observed predation by House Mice (Mus musculus) (Dilley et al. 2018).

 Quantify the breeding population in Western Australia

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