Grey Petrel
Procellaria cinerea
Number Of Mature
Individuals (Regional)
12 000
Regional
Population Trend
Decreasing
2025
Regional Category
Endangered
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CONTENTSOverview
Names
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IOC English Name: |
Grey Petrel |
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SA & IOC Scientific Name: |
Procellaria cinerea |
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BirdLife International Taxonomy (scientific name): |
Procellaria cinerea |
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Order: |
PROCELLARIIFORMES |
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Family: |
Procellariidae |
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Species name author: |
Gmelin 1789 |
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Afrikaans: |
Pediunker |
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Sesotho (South Africa): |
Leebafefo le leputswa |
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Sesotho (Lesotho): |
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Siswati: |
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Zulu: |
umantantomaphikampunga |
Current Assessment Status
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2025 Regional Category [Criteria] |
EN [A3be; B2ab(v)] |
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2024 Global Category [Criteria] |
NT [A2de+3de+4de] (BirdLife International 2021) |
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Population size (Regional) |
12 000 mature individuals (Ryan and Bester 2008) |
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Population size (Global) |
151 500 (BirdLife International 2021) |
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Distribution size (EOO) (Regional) km2 |
c. 720 (breeding) |
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Distribution size (EOO) (Global) km2 |
146 000 000 |
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Distribution size (AOO) (Regional) km2 |
334 (breeding) |
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Generation time |
16.5 years (BirdLife International 2021) |
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Status change reason |
Genuine change in status |
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Migrant (in the region) |
No |
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Regional endemic |
No |
Historic Listing Information
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2000 Regional Status |
NT [A1d+2d] |
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2015 Regional Status |
VU [A2cde+3cde+4cde; D2] |
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Status change reason (if applicable) |
Application of criteria |
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2015 Population size (Regional) |
12 000 mature individuals |
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2015 Global Status |
NT [A2cde+3cde+4cde] |
Reason for Inclusion
Reason for Inclusion in the Assessment
The Grey Petrel Procellaria cinerea is globally Near Threatened and breeds on the Prince Edward Islands. Grey Petrel was regionally assessed as Vulnerable in 2015 (Taylor 2015).
Category Justification
Category Justification
The regional population of Grey Petrel breeds at two locations in the region namely Prince Edward Island and Marion Island. This species is declining, with projected future declines based on expert-assessed extinction horizons due principally to the threat of House Mice Mus musculus on Marion Island (Preston et al. 2019). While there is limited direct evidence of ongoing population decline currently, predictive assessments suggest that the species may experience a significant reduction over the next three generations. The extinction horizon estimates indicate that the species’ population may decline by 50% within this period, meeting threshold for Endangered under A3 (Lee 2025).
Furthermore, the Area of Occupancy (AOO) is c. 335 km2 which along with the continued decline of mature individuals and location size results in Criterion B2 being invoked.
Given that the global population is Near Threatened and it is not known whether a Regional Rescue Effect is plausible, the Category is retained as Endangered [A3be; B2ab(v)].
Population Justification
The global population is estimated at 75 610 breeding pairs (Phillips et al. 2016) or c. 151 500 mature individuals (BirdLife International 2021). Burrow-nesting species are challenging to census accurately, so there is very limited information on population trends. Ryan and Bester (2008) provide estimates of 2000 mature individuals on Marion Island and 10 000 mature individuals breeding on Prince Edward Island, giving a regional population estimate of 12 000 mature individuals. Confidence in this estimate is low.
Trend Justification
Confidence in the global population trend is low (BirdLife International 2021) but moderately rapid declines are suspected. On Marion Island, a low breeding success (34 ± 21%) has been reported over a four-year period (2012-2016), most likely as the result of predation by the invasive house mouse (Dilley et al. 2018). Future population projections based on extinction horizon estimates suggest that significant reductions (50%) may occur within the next three generations (Preston et al. 2019). While no significant recent declines have been observed, the potential for future declines justifies careful consideration under Criterion A3 (Lee 2025). Ongoing monitoring is essential to validate these projections and determine whether the species is experiencing measurable population decreases.
Biology & Ecology
Taxonomy
Formerly placed in the monospecific genus Adamastor but now included in Procellaria. The species is monotypic.
Identification
50 cm, 1 kg. Sexes alike. A medium-large grey petrel with contrasting white underparts. Above, including upperwing coverts, silvery grey with a slightly paler neck. Grey cap extends below the eye. Flight feathers and primary coverts grey- brown. Underwing and undertail medium grey. Underparts white. Bill creamy or yellowish horn with darker tip. Eyes dark brown. Legs and feet grey (Ryan 2005).
Distribution
The Grey Petrel has a circumpolar distribution in Subantarctic and subtropical waters, mostly between 37°S and 49°S but extending further north in the Humboldt Current to about 18°S off the east coast of South America (Marchant and Higgins 1990). It breeds on several South African, French, New Zealand and Australian Subantarctic islands, as well as on Amsterdam Island, and in the Gough and Tristan de Cunha group (Brooke 2004). The species also breeds on both Prince Edward and Marion islands (the reason for its inclusion here). It is a rare non-breeding vagrant to continental South African waters, generally remaining in the Southern Ocean for the majority of the year and seldom venturing north of the Subtropical Convergence (Ryan and Bester 2008).
Ecology
The Grey Petrel is a burrow-nesting, colonial, winter breeder (Cooper and Brown 1990). 93% of successful breeding birds return the following season (Chastel 1995). It lays a single egg, which is not replaced if the breeding attempt fails (Warham 1990). Their breeding period overlaps with that of White-chinned Petrels Procellaria aequinoctialis, sometimes resulting in both species killing or evicting the other’s chicks (Dilley et al. 2019). A generation length of 16.5 years is provided by BirdLife International (2021). The foraging methods of Grey Petrel are poorly known (Ridoux 1994), but it is thought to feed predominantly by surface-seizing. Analysis of stomach contents of chicks shows that the species feeds primarily on squid (70.5%) and fish (27.8%) (Ridoux 1994). The species is attracted to trawlers and other fishing vessels (Ryan and Rose 1989).
Threats & Conservation
Threats
The primary threat to the global population is incidental mortality caused by commercial longline fisheries (Huyser 2000). The species is the most commonly caught seabird in New Zealand fisheries and Barbraud et al. (2009) reported declines due to fishery bycatch at the Kerguelen Islands. Regionally, relatively few were killed on toothfish longlines around the Prince Edward Islands (Nel et al. 2002). The species is susceptible to introduced mammalian predators with populations on Gough Island being thought to have been subjected to considerable predation from introduced mice (Wanless et al. 2007) and the extirpation of the species on Macquarie Island being attributed to cats and rats. Prior to eradication in the early 1990s, feral cats on Marion Island predated this species (van Aarde 1980). There are no accurate data to monitor the recovery of burrowing petrel populations at Marion Island (Ryan and Bester 2008), but it is thought that the Grey Petrel, a winter breeder, came under extreme pressure from predation by cats. It has now been confirmed that Grey Petrels are indeed also under pressure from invasive house mice, resulting in high mortality rates of young chicks (Dilley et al. 2018).
Conservation Measures Underway
The Grey Petrel is protected internationally under the Agreement on the Conservation of Albatrosses and Petrels – Annex 1. The species is currently listed as globally Near Threatened and is included in Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals. The Prince Edward Islands are listed as a Ramsar Wetland of International Importance, and as a Special Nature Reserve under the Environment Conservation Act (No 73 of 1989) and the Prince Edward Islands Management Plan 1996. The Prince Edward Islands Marine Protected Area was proclaimed in 2013. A feasibility study for eradication plans to rid Marion Island of mice is currently underway.
Conservation Measures Proposed
Public awareness regarding the conservation needs of large petrels should be increased. Mitigation strategies to reduce accidental bycatch for fisheries must be maintained.
Research Priorities and Questions
- Monitoring of mortality rates, population numbers and population trends in the Grey Petrels breeding at the Prince Edward islands should be a priority.
- Trends or changes in adult and juvenile survival rates, and the factors impacting upon this, should be investigated.
- Levels of overlap with fishing operations and incidence of bycatch should be documented, so that mitigation measures can be implemented.
Contributors & References
Assessor/s
Shamiso Banda
Reviewer/s
Stefan Schoombie, Ben Dilley
References
Barbraud C, Delord K, Marteau C, Weimerskirch H. 2009. Estimates of population size of white-chinned petrels and grey petrels at Kerguelen Islands and sensitivity to fisheries. Animal Conservation 12: 258–265.
BirdLife International. 2021. Procellaria cinerea. The IUCN Red List of Threatened Species 2021: e.T22698159A175348962. Available: https://dx.doi.org/10.2305/IUCN.UK.2021-3.RLTS.T22698159A175348962.en. [Accessed on 18 August 2023].
Brooke MD. 2004. Albatrosses and Petrels Across the World (Bird Families of the World). Oxford, United Kingdom: Oxford University Press.
Chastel O. 1995. Influence of reproductive success on breeding frequency in four southern petrels. Ibis 137: 360–363.
Cooper J, Brown C. 1990. Ornithological research at the Subantarctic Prince Edward Islands: a review of achievements. South African Journal of Antarctic Research 20: 40–57.
Dilley BJ, Schoombie S, Stevens K, Davies D, Perold V, Osborne A, Schoombie J, Brink CW, Carpenter-Kling T, Ryan PG. 2018. Mouse predation affects breeding success of burrow-nesting petrels at sub-Antarctic Marion Island. Antarctic Science 30(2): 93–104.
Dilley BJ, Davies D, Stevens K, Schoombie S, Schoombie J, Ryan PG. 2019. Burrow wars and sinister behaviour among burrow-nesting petrels at sub-Antarctic Marion Island. Ardea 107: 97–102.
Huyser O. 2000. Grey Petrel Preocellaria cinera. In: Barnes KN (ed), The Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland. Johannesburg, South Africa: BirdLife South Africa. pp 135.
Lee ATK. 2025. The application of IUCN Regional Red List Criteria to the species of South Africa’s Prince Edward Islands. Unpublished report. Johannesburg: BirdLife South Africa.
Marchant S, Higgins PJ. 1990. Handbook of Australian, New Zealand and Antarctic birds, Volume I: Ratites to Ducks. Melbourne, Australia: Oxford University Press.
Nel DC, Ryan PG, Watkins BP. 2002. Seabird mortality in the Patagonian toothfish longline fishery around the Prince Edward Islands, 1996-2000. Antarctic Science 14: 151–161.
Phillips RA, Gales R, Baker GB, Double MC, Favero M, Quintana F, Tasker ML, Weimerskirch H, Uhart M, Wolfaardt A. 2016. The conservation status and priorities for albatrosses and large petrels. Biological Conservation 201: 169–183.
Preston GR, Dilley BJ, Cooper J, Beaumont J, Chauke LF, Chown, SL, Devanunthan N, Dopolo M, Fikizolo L, Heine J, Henderson S, Jacobs CA, Johnson F, Kelly J, Makhado AB, Marais C, Maroga J, Mayekiso M, McClelland G, Mphepya J, Muir D, Ngcaba N, Ngcobo N, Parkes JB, Paulsen F, Schoombie S, Springer K, Stringer C, Valentine H, Wanless RM, Ryan PG. 2019. South Africa works towards eradicating introduced house mice form the sub-Antarctic Marion Island: the largest island yet attempted for mice. In: Island Invasives: Scaling up to Meet the Challenge. Veitch CR, Clout MN, Martin AR, Russell JC, West CJ (Eds.). Occasional Paper of the IUCN Species Survival Commission; Vol. 62 pp 40–46. IUCN. https://portals.iucn.org/library/node/48358.
Taylor MR. 2015. Grey Petrel. In: Taylor MR, Peacock F, Wanless RM (eds), The Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland. Johannesburg, South Africa: BirdLife South Africa. pp 251–252.
Ridoux V. 1994. The diets and dietary segregation of seabirds at the subantarctic Crozet Islands. Marine Ornithology 22: 1–192.
Ryan PG. 2005. Grey Petrel Procellaria cinerea. In: Hockey PAR, Dean WRJ, Ryan PG (eds), Roberts Birds of Southern Africa, 7th Edn. Cape Town, South Africa: The Trustees of the John Voelcker Bird Book Fund. pp 669–670.
Ryan PG, Bester MN. 2008. Pelagic Predators. In: Chown SL, Froneman PW (eds), The Prince Edward Islands: land-sea interactions in a changing ecosystem. Stellenbosch, South Africa: Sun Media. pp 121–164.
Ryan PG, Rose B. 1989. Migrant seabirds. In: Payne AIL, Crawford RJM (eds), Oceans of Life off Southern Africa. Cape Town, South Africa: Vlaeberg. pp 274–287.
van Aarde RJ. 1980. The diet and feeding behaviour of feral cats, Felis catus, at Marion Island. South African Journal of Wildlife Research 10: 123–128.
Wanless RM, Angel A, Cuthbert RJ, Hilton GM, Ryan PG. 2007. Can predation by invasive mice drive seabird extinctions? Biology Letters 3: 241–244.
Warham J. 1990. The Petrels: Their Ecology and Breeding Systems. London, United Kingdom: A&C Black.
Citation
Banda S 2025. Grey Petrel. In: Lee ATK, Rose S, Banda S, Bezeng SB, Maphalala MI, Maphisa DH, Smit-Robinson H (eds), The 2025 Red Data Book of Birds of South Africa, Lesotho and Eswatini. Johannesburg, South Africa: BirdLife South Africa. Available at: https://www.birdlife.org.za/red-list/grey-petrel/
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