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).

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 estimated to be 75,610 pairs (Phillip et al. 2016). Its largest breeding population was once 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). 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 250-1000 mature adults on Macquarie following eradication of invasive mammals on the island (Bird et al., in prep 2020). 

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). In Australian territories, Macquarie Island is fully protected and a World Heritage Area, and fisheries are monitored and managed under the Threat Abatement Plan. Grey Petrel is also listed as threatened under the Environmental Protection and Biodiversity Conservation Act (Bird et al., in prep 2020).

Conservation Actions Proposed
Census the population on all the breeding islands. Conduct regular monitoring of a representative proportion of the population. 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.