It typically nests in loose colonies on grassy or bare ground. However, in the Falkland Islands (Islas Malvinas) it can nest in large, relatively dense colonies (Reid and Huin 2005). Average age of first breeding is c.7 years, and mean adult annual survival at South Georgia is 90% (Hunter 1984a). It feeds on carrion, cephalopods, krill, offal, discarded fish and refuse from ships, often feeding near trawlers and longliners (Hunter and Brooke 1982, Hunter 1983). Males and females exhibit clearly defined spatial segregation in their foraging ranges (Gonzalez-Solis et al. 2000, BirdLife International 2004, Quintana et al. 2010).

Macronectes giganteus breeds on the Falkland Islands (Islas Malvinas), Staten Island and islands off Chubut Province (Argentina), South Georgia (Georgias del Sur), the South Orkney (Orcadas del Sur) and South Shetland Islands (Shetland del Sur), islands near the Antarctic Continent and Peninsula, Prince Edward Islands (South Africa), Crozet Islands (French Southern Territories), Heard Island and Macquarie Island (Australia), with smaller populations on Gough Island, Tristan da Cunha (St Helena to UK), Diego Ramirez and Isla Noir (Chile), Kerguelen Islands (French Southern Territories), and four localities on the Antarctic Continent including Terre Adélie. In the 1980s, the population was estimated at 38,000 pairs (Hunter 1985), declining by 18% to 31,000 pairs in the late 1990s (Rootes 1988). Populations at Heard and Macquarie declined 50% between the 1960s and late 1980s (Woehler 1991, 2006). Many Antarctic Peninsula populations decreased to the mid-1980s (e.g. >50% at Signy, South Orkneys) (Patterson et al. undated). The population at Terre Adélie declined from c.80 pairs in the 1960s to 10-15 pairs in 2000. However, recent data indicate a number of populations have stabilised or increased, e.g. Prince Edward Islands (Ryan et al. 2009), Possession Island (Crozet) (Patterson et al. undated), Gough Island (Cuthbert et al. 2014, RSPB and UCT unpubl. data), Heard Island (Woehler 2006), and Isla Arce and Gran Robredo (Chubut, Argentina) (Quintana et al. 2006). A comprehensive 2004-2005 survey of all breeding colonies on the Falkland Islands (Islas Malvinas) recorded 19,523 breeding pairs (Reid and Huin 2005). This represents an increase over the previous estimate of 5,000-10,000 pairs in the Falkland Islands (Islas Malvinas), and is thought to represent a combination of improved knowledge and a genuine population increase. Similarly, a comprehensive survey of all known breeding sites in the South Georgia archipelago, between 2005 and 2006, indicates a population increase since the 1980s (Poncet et al. in litt. 2008), and the global population is now estimated at c.54,000 breeding pairs (Chown et al. unpubl. report 2008). Data from birds tracked from South Georgia indicate that breeders remain in the same ocean sector during the non-breeding season (Hunter and Brooke 1982) which is also the case for birds tracked from islands off Chubut Province (Argentina) (Blanco and Quintana 2014). By comparison, ringing recoveries and satellite tracking of individuals suggest that juveniles disperse much more widely (Hunter 1984b, Copello et al. 2009, Blanco and Quintana 2014, Thiers et al. 2014). Males and females have distinct foraging ranges during the breeding season (Gonzalez-Solis and Croxall 2005, Quintana et al. 2010).

Conservation Actions Underway
CMS Appendix II and ACAP Annex 1. It is monitored at South Georgia, Marion, Crozet and Macquarie Islands, and at Terre Adélie. Several breeding islands are nature reserves; Gough and Macquarie are World Heritage Sites. The population at Gough Island has been counted annually since 2003, and a monitoring protocol for breeding success and adult survival is in place (Cuthbert et al. 2014). 

Conservation Actions Proposed
Continue monitoring. Conduct surveys of major breeding sites. Minimise disturbance at breeding sites. Research movements and migration. Promote adoption of best-practice mitigation measures in all fisheries within its range, particularly via existing and proposed intergovernmental mechanisms under auspices of CCAMLR, CMS and FAO.