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Grey Petrel Procellaria cinerea



Justification

Justification of Red List Category
Although there are no current data on the population trend, this species is susceptible to introduced mammalian predators, having been previously extirpated from Macquarie Island by cats and rats, and it has been commonly caught in longline fisheries in New Zealand waters. Evidence from Gough Island, formerly thought to contain the largest population of this species, suggest that the species is likely to be subjected to considerable predation from introduced mice, which are a major predator on other winter-breeding seabirds. The population on the Kerguelen Islands may also be in decline due to fishery bycatch. Based on these data, a moderately rapid decline is suspected and, as such, the species is listed as Near Threatened. Further data are urgently required in order to more accurately assess its population numbers and trends.

Population justification
Figures suggest a very tentative world population around 400,000 individuals, a figure that could be incorrect by a factor of 2-3 either way (Brooke 2004). A tally of the most recent figures points to at least 80,000 pairs worldwide, but this is thought to be only a rough estimate.

Trend justification
This species is susceptible to introduced mammalian predators, having been previously extirpated from Macquarie Island by cats and rats, and today, it is one of the bycatch species in longline fisheries in New Zealand waters. The population on the Kerguelen Islands may also be in decline due to fishery bycatch (Barbraud et al. 2009). Evidence from Gough Island, formerly thought to contain the largest population of this species, suggest that P. cinerea are likely to be subjected to considerable predation from introduced mice, which are a major predator on other winter-breeding seabirds. Hence moderately rapid declines are suspected, but further data are urgently required in order to more accurately assess its population numbers and trends.

Distribution and population

This species has a circumpolar distribution between 32-58 degrees South, but somewhat to the north in the Humboldt Current and off the east coast of South America (Brooke 2004). It breeds on Gough Island and other islands in the Tristan da Cunha group (St Helena, to UK), Prince Edward and Marion Islands (South Africa), Crozet, Kerguelen and Amsterdam Islands (French Southern Territories), Campbell and the Antipodes Islands (New Zealand), and Macquarie Island (Australia). Its total population size is poorly known. Its largest breeding population was believed to be in the Tristan da Cunha group: in the early 1970s, hundreds of thousands of individuals were guessed to breed at Gough Island (Richardson 1984). However, the most recent estimate for Gough Island suggests a population of >10,000 pairs (Cuthbert and Sommer 2004), with pairs only sparse in the uplands (Imber 1983), and thus the population on Gough may be far lower than on the Antipodes (R. Cuthbert in litt. 2008). A small number of pairs also breed on Tristan da Cunha itself; 50-100 pairs estimated in 1972-1974 (Richardson 1984 in Angel and Cooper 2006). The largest population is therefore likely to be on the Antipodes Islands, with 48,960 pairs estimated in 2010 (Bell 2002, Bell et al. 2013). In addition, several thousand pairs are estimated at Prince Edward, Crozet and Kerguelen Islands. One estimate in 2006 on the Kerguelen Islands gave a figure of 1,900-5,600 breeding pairs, though some nesting sites were not sampled. Figures from Crozet in 2005 indicated the occurrence of 5,500 pairs (ACAP 2009). Only c.10 pairs breed on Amsterdam Island (J.C. Stahl per S. Bartle in litt. 2000), although the fossil record indicates that one of the world's largest colonies probably occurred there (Worthy and Jouventin 1999). The first quantitative population estimate on Campbell Island and surrounding islets estimated c. 96 pairs from the four colonies. Since work was conducted during the middle of the chick-rearing stage, this is likely an underestimate of the breeding population (Parker et al. 2016). There are now >90 pairs on Macquarie following eradication of invasive mammals on the island. There is no population trend data for most of the sites, but based on a population model and data from fisheries, this population may be in decline due to bycatch (Barbraud et al. 2009).

Ecology

Behaviour Birds return to the breeding colonies in the austral autumn, first appearing in February and March and often flying to land during diurnal hours. Eggs are laid in late March and early April, and chicks fledge in late September to early December. The asynchrony in fledging dates within sites and years is thought to reflect food scarcity and variability during the winter, rather than asynchrony in laying. The estimated mean age of the first breeding is 7 years (Barbraud et al. 2009). The species typically forages alone or in groups of three or four, but also occasionally in larger flocks over 50 birds (ACAP 2009).
Habitat Breeding It nests in burrows on well-drained areas, often dominated by Poa tussock grass, where the ground may be steep.
Diet Cephalopods are the main prey item, followed by fish remains (ACAP 2009).
Foraging range Data obtained from seabird bycatch suggest that during the breeding season in the austral winter, females forage further north than males, in waters north of the Subtropical Convergence, up to 1,460 km from their colonies on Sub-Antarctic islands (ACAP 2009).

Threats

The Grey Petrel is the species most frequently killed by the tuna-longline fishery in New Zealand Waters, with up to 45,000 birds caught in the last 20 years (S. Bartle in litt. 2000). 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 (Huyser et al. 1999). A strict minimum of 755 individuals are taken annually in the Patagonian fisheries operating around the Kerguelen Islands, which exceeds the value that has been predicted would lead to population declines on these islands (Barbraud et al. 2009).

Invasive species also represent a significant threat to the Grey Petrel. On Marion Island predation by mice is causing a considerable reduction in breeding success and the behaviour appears to be spreading rapidly (Dilley et al. 2018). Brown Rat predation is thought to have constrained the population on Campbell Island until an eradication programme in 2001 and may still be constraining the Amsterdam Island population, which may historically have been the largest in the world. House Rat predation appears to have caused considerable declines and possibly extinctions of this species within the Kerguelen Islands, and the presence of rats appears to be preventing recolonisation of some sites. Previously, the Weka is thought to have had some effect on the breeding population on Macquarie Island however, since the eradication of the Weka on this island, it is no longer believed to be significantly impacting Grey Petrel. European Rabbits may cause habitat degradation and a loss of reproductive success on some islands.

Conservation actions

Conservation Actions Underway
CMS Appendix II and ACAP Annex 1. Gough Island is a World Heritage Site. In 2001, a study was conducted on the Antipodes Islands on the feasibility of establishing long term monitoring plots. Brown Rats were eradicated from Campbell Island in 2001. Mice eradication projects took place on the Antipodes Islands in 2016 (to be confirmed in 2018/19). In 2006, the South East Atlantic Fisheries Commission (SEAFO) passed a resolution to require all its longline vessels to use a tori line and to set lines at night. In 2007, the New Zealand government began a five year study of Procellaria petrels on Antipodes Island which will investigate issues such as population size and trends, annual survival rates of adults and breeding frequency. Geolocation loggers and other tracking devices will be applied to birds to determine foraging zones and migration routes (G. Taylor in litt. 2008). Foraging zones and migration routes have been identified for the Kerguelen population (Delord et al. 2013). A 120 000 km² marine protected area has been established in the French Southern Territories with no fishing activities (http://www.taaf.fr/IMG/pdf/decret_extension_rnn.pdf).

Conservation Actions Proposed
Census the population on all the breeding islands. Conduct regular monitoring of a representative proportion of the population. Determine if predation by mice is a serious threat on Gough Island. Determine the at-sea distribution of the species through tracking studies and the interaction with longline fisheries. Promote the adoption of a) monitoring of seabird bycatch associated with longline fishing and b) best-practice mitigation measures in all fisheries within the species's range, particularly via intergovernmental mechanisms such as ACAP, the FAO, and Regional Fisheries Management Organisations.

Identification

48cm. A large (c. 1000g) ash-grey and white petrel with brownish grey mantle, back, uppertail-coverts and upperwings, and dark grey underwings, contrasting with white belly. It readily plunges from heights of up to 10m and swims underwater using wings (Harrison 1985). Similar spp. Differs from White-headed Petrel in having dark grey cap, and from other larger petrels and shearwaters in combination of white underparts and wholly dark underwing (Brooke 2004).

Acknowledgements

Text account compilers
Stuart, A., Sullivan, B., Symes, A., Calvert, R., Anderson, O., Hermes, C., Martin, R., Moreno, R., Small, C., Stattersfield, A., Fjagesund, T.

Contributors
Barbraud, C., Stahl, J.-C., Bell, E., Parker, G., Bartle, S., Taylor, G.A., Bond, A., Garnett, S., Cuthbert, R.


Recommended citation
BirdLife International (2019) Species factsheet: Procellaria cinerea. Downloaded from http://www.birdlife.org on 20/10/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/10/2019.