Gray Petrel

The grey petrel breeds in colonies, making its nest in burrows (8). The breeding ecology of this little understood, winter breeding bird was studied on the Kerguelen Archipelago, where adults were recorded to mate in February (9). A single egg would be laid in early April, and hatching took place in late May to early June (9). The fledging period of 120 to 160 days is the longest known among the petrels, with a long fledging period being particularly associated with southern winter breeding species (9). Grey petrels forage in sub-Antarctic waters for squid, fish and crustaceans (6), and can dive to depths of up to 10 m by using their wings underwater (7). With an ability to dive so deep, these inquisitive birds are particularly attracted to food scraps around fishing boats (7).

The grey petrel is listed on Appendix II of the Convention on the Conservation of Migratory Species (CMS), which states that these species would significantly benefit from international cooperation (10). It is also on Annex 1 of the Agreement on the Conservation of Albatrosses and Petrels (ACAP), which seeks to coordinate activity to mitigate known threats to albatrosses and petrels (11). Additionally, The Royal Forest and Bird Protection Society (BirdLife International partner in New Zealand) is developing a proposal for a national network of open-ocean marine reserves that protect albatrosses and petrels at sea, as well as their feeding grounds (12). There is a pressing need to collect more information on the grey petrel, especially the impact of mouse predation on Gough Island, which could result in its reclassification as Threatened (3). Hopefully, such reclassification would help raise awareness of the plight of this magnificent, soaring seabird, and encourage greater conservation efforts to help save it from yet further local extinctions.

Despite being called petrels, Procellaria species are thought to be more closely related to Calonectris shearwaters than to other petrels (4). Indeed, grey petrels resemble the larger shearwaters in their relatively bulky bodies (5). The crown, wings, back and tail are a dark ash gray colour, while the cheeks and the sides and nape of the neck are pale grey (2). By contrast, the throat, chest and abdomen are white (2).

The grey petrel is pelagic, returning to nesting islands and coastal cliffs only to breed (1) (3).

A circumpolar sub-Antarctic species (6) that breeds on islands in the Pacific, Atlantic and Indian Oceans (7). These include Gough Island and the Tristan da Cunha group (St Helena, UK), Prince Edward and Marion islands (South Africa), Crozet, Kerguelen and Amsterdam islands (French Southern Territories), and Campbell and the Antipodes islands (New Zealand) (3). The bird was previously driven to extinction on Macquarie Island (Australia) but has recently recolonised (3). Gough and Antipodes are believed to support the bulk of the current population (3).

Classified as Near Threatened (NT) on the IUCN Red List (1), listed under Appendix II of the Convention on the Conservation of Migratory Species (CMS) and Annex 1 of ACAP (3).

Sadly, the grey petrel is a frequent victim of long-line fishing (7). In New Zealand waters, this petrel is the most frequently killed species by tuna-longline fisheries, with around 45,000 birds thought to be caught in the last 20 years (3). Substantial incidental mortality has also been recorded in fisheries off Australia, and it may be caught in significant numbers in international waters in the southern Indian Ocean, for which little seabird bycatch information exists (3). This species is particularly vulnerable to such dangers because of its attraction to food scraps around fishing boats (7). An additional serious threat comes from introduced predators on the breeding islands, such as cats and black rats (Rattus rattus) on Crozet and Kerguelen, brown rats (Rattus norvegicus) on the Campbell Islands and, until their fairly recent eradication, cats on Marion Island (3). Prioir to its successful recolonisation, the bird's extinction on Macquarie Island was probably the result of predation by cats, weka (Gallirallus australis) and brown rats (R. norvegicus). Cats are also responsible for its near extinction on Amsterdam Island (3). Recently there has been serious concern that introduced house mice (Mus musculus) on Gough Island may be preying upon the eggs and chicks of this species. The mice have already had a significant impact on the breeding success of other threatened birds on the island (3). Population trends have not been quantified, but this species has clearly suffered a historic reduction in numbers and could be continuing suffer severe declines as the result of these combined threats (3).