Salvin’s Prion
Pachyptila salvini
Number Of Mature
Individuals (Regional)
800 000
Regional
Population Trend
Decreasing
2025
Regional Category
Near Threatened
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CONTENTSOverview
Names
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IOC English Name: |
Salvin’s Prion |
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SA & IOC Scientific Name: |
Pachyptila salvini |
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BirdLife International Taxonomy (scientific name): |
Pachyptila salvini |
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Order: |
PROCELLARIIFORMES |
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Family: |
Procellariidae |
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Species name author: |
Mathews 1912 |
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Afrikaans: |
Marionwalvisvoël |
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Sesotho (South Africa): |
Leebaruarua la Marion |
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Sesotho (Lesotho): |
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Siswati: |
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Zulu: |
impungemlomobanzana |
Current Assessment Status
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2025 Regional Category [Criteria] |
NT° [A3e] |
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2024 Global Category [Criteria] |
LC (BirdLife International 2018) |
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Population size (Regional) |
c. 800 000 mature individuals (Dilley 2018) |
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Population size (Global) |
12 million individuals (Brooke 2004) |
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Distribution size (EOO) (Regional) km2 |
c. 720 (breeding) |
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Distribution size (EOO) (Global) km2 |
38 000 000 (breeding/resident) |
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Distribution size (AOO) (Regional) km2 |
334 (breeding) |
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Generation time |
9.69 years (Bird et al. 2020) |
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Status change reason |
No Change |
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Migrant (in the region) |
Native and breeding visitor |
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Regional endemic |
No |
Historic Listing Information
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2000 Regional Status |
LC |
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2015 Regional Status |
NT [D2] |
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Status change reason (if applicable) |
Application of criteria |
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2015 Population size (Regional) |
c. 700 000 mature individuals |
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2015 Global Status |
LC |
Reason for Inclusion
Reason for Inclusion in the Assessment
Salvin’s Prion Pachyptila salvini breeds on the Prince Edward Islands and was classified as regionally Near Threatened in 2015.
Category Justification
Category Justification
The regional population of Salvin’s Prion qualifies for Vulnerable (VU) under Criterion A3 due to projected future declines based on expert-assessed extinction horizons resulting principally from the threat of House Mice Mus musculus on Marion Island (Preston et al. 2019). While there is limited direct evidence of ongoing population decline at the time of writing, 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 41% within this period, exceeding the threshold for VU [A3] (Lee 2025).
Since a Regional Rescue Effect is applicable given the pelagic nature of the species, plus a non-threatened global population, the Category is modified to: NTo A3.
Population Justification
Brooke (2004) estimated a global population of over 12 000 000 individuals. Barnes and Huyser (1998) reported a regional population size of 100 000s on Marion Island and in the 10 000s on Prince Edward Island. Ryan and Bester (2008) later updated these figures, indicating around 200 000 on Marion Island and potentially up to 500 000 on Prince Edward Island. This led to a total regional estimate of approximately 700 000 individuals. Since then, Dilley (2018) gave a Marion Island estimate of 150 000 breeding pairs (or 300 000 mature individuals), updating the regional population estimate to at least 800 000 mature individuals. The lack of updates from Prince Edward Island results in medium confidence in this regional population estimate.
Trend Justification
The population is suspected to be stable or increasing in the absence of evidence for any declines. Increases have been reported since 1998 (Barnes and Huyser 1998, Ryan and Bester 2008, Dilley 2018). However, future population projections based on extinction horizon estimates suggest that significant reductions 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
The taxonomy of prions is considerably confused due to the group’s remarkably consistent plumage traits. While size, especially bill size, serves as crucial distinguishing features, these traits can vary, leading to overlapping characteristics among many potential species (Cox 1980). Salvin’s Prion, on the other hand, has typically remained undisputed in its classification (Onley and Scofield 2007).
Identification
28 cm, 180 g. This prion exemplifies typical characteristics, falling between the Broad-billed Prion P. vittata and the Antarctic Prion P. desolata in terms of size and appearance. However, identifying it at sea can be uncertain. Both sexes share identical features, featuring a pale blue-grey upper plumage with a slightly darker crown. Notably, there is a short, narrow white supercilium extending from the area in front of the eyes to behind the ear coverts.
Distinctive markings include an M-shaped pattern on the back and wings, formed by dark grey outer primaries and primary coverts, as well as a diagonal bar extending from the carpals to the base of the wing and across the lower back. The upper back and rump are primarily grey. Underneath, the wings are predominantly white with grey outer primaries, while the tail is tipped in black, with the outermost rectrices being pale grey. The underparts are mostly white, except for a prominent blue-grey band on the sides of the breast and a dark grey tip on the undertail. The eyes are dark brown, the bill is blue-grey, and the legs and toes exhibit a blue hue (Ryan 2005).
Distribution
Salvin’s Prion occurs throughout the southern Indian Ocean and the western Pacific. This bird species has established breeding grounds at the Crozet Islands and the Prince Edward Islands, both situated in the southern Indian Ocean (Jouventin et al. 1984). At Marion and Prince Edward Islands in South Africa, it stands as the most populous breeding petrel, constituting a significant portion of the avian population on these islands (Berruti and Hunter 1986). Throughout the majority of the year, these birds remain within the Southern Ocean, seldom venturing beyond the Subtropical Convergence Zone (Ryan and Bester 2008). Although considered a rare visitor to South African waters, it’s important to note that its presence may go unnoticed due to the substantial challenge of distinguishing prions at sea.
Ecology
Salvin’s Prion is a burrow-nesting seabird. It prefers to construct its burrows in steep, vegetated slopes but will also nest in natural cavities between blocks of lava (Schramm 1986). Increased burrow densities were recently reported on Marion Island in steep vegetated slopes, partly vegetated lava hummocks, and cinder slopes (Dilley et al. 2017). The size and shape of their burrow entrances on Marion Island are relatively small compared to other burrowing birds, at 112 ± 10 mm wide by 96 ± 9 mm, and they display a preference for burrowing in Acaena and Azorella selago (Dilley et al. 2017). Interestingly, one entry into a nest may lead to multiple chambers (Dilley 2018). Adults are not tolerant of disturbance at the nest (Berruti and Hunter 1986). Laying takes place in November and chicks hatch in January (Berruti and Hunter 1986). A revised generation length of 9.69 years is provided by Bird et al. (2020). Salvin’s Prion occurs singly or with other prion species (Ryan 2005), and feeds by surface-seizing and through the filtering of prey while hydroplaning (Marchant and Higgins 1990). Prey includes small crustaceans, small fish, cephalopods and chaetognaths (Gartshore et al. 1988).
Threats & Conservation
Threats
The population on Marion Island was heavily predated upon by introduced cats Felis catus, with approximately 30% of all cat stomachs containing remains of Salvin’s Prion while 60% of the 1224 prey remains identified contained Salvin’s Prion (van Aarde 1980). Fortunately, this threat has been negated by the eradication of cats from the island (Bester et al. 2002). Chicks are preyed upon by Subantarctic Skuas Stercorarius antarcticus (Berruti and Hunter 1986) which will excavate burrows to reach the nest chamber (Sinclair 1980). Adults are predominantly preyed upon by female Giant Petrels (Hunter and Brooke 1992), and an incubating Northern Giant Petrel was recently seen feeding on a Salvin’s Prion while on her nest (Jones et al. 2019). Dilley (2018) estimated local extirpation in 50 to 100 years if mice are not eradicated from Marion Island. Outside the region, samples collected from Australia and New Zealand have linked marine debris ingestion to the mortality of Salvin’s Prions (Roman et al. 2019).
Conservation Measures Underway
From a global perspective, the Prince Edward Islands are an exceptionally important breeding site for the world’s Salvin’s Prion population (Ryan and Bester 2008). While no conservation measures specific to this species are in place, the islands are safeguarded by stringent guidelines for visiting researchers. 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 managed under the Prince Edward Islands Management Plan 1996. The Prince Edward Islands Marine Protected Area was proclaimed in 2013. Mouse eradication on Marion Island is being planned.
Conservation Measures Proposed
Populations should be monitored regularly, in order to detect any changes in population numbers.
Research Priorities and Questions
- Updated regional population estimates are needed.
- Severity of predation of prion chicks by introduced mice should be investigated.
- A method of accurately estimating population size and densities of burrow-nesting procellariiform seabirds should be developed.
- An investigation of marine debris ingestion and mortality should be undertaken.
Contributors & References
Assessor/s
Shamiso Banda
Reviewer/s
Stefan Schoombie
References
Barnes KN, Huyser O. 1998. The Prince Edward Islands Important Bird Area. In: Barnes KN (ed), The Important Bird Areas of southern Africa. Johannesburg, South Africa: BirdLife South Africa. pp 269–272.
Berruti A, Hunter S. 1986. Some aspects of the breeding biology of Salvin’s prion Pachyptila vittata salvini at Marion Island. Cormorant 13: 98–106.
Bester MN, Bloomer JP, van Aarde RJ, Erasmus BH, van Rensburg PJJ, Skinner JD, Howell PG, Naude TW. 2002. A review of the successful eradication of feral cats from Subantarctic Marion Island, Southern Indian Ocean. South African Journal of Wildlife Research 32: 65–73.
Bird JP, Martin R, Akçakaya HR, Gilroy J, Burfield IJ, Garnett ST, Symes A, Taylor J, Şekercioğlu ÇH, Butchart SH. 2020. Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology 34: 1252–1261.
BirdLife International. 2018. Pachyptila salvini. The IUCN Red List of Threatened Species 2018: e.T104062546A132674879. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T104062546A132674879.en. [Accessed on 12 September 2023].
Brooke MD. 2004. Albatrosses and Petrels Across the World (Bird Families of the World). Oxford, United Kingdom: Oxford University Press.
Cox J. 1980. Some remarks on the breeding distribution and taxonomy of the prions (Procellariidae: Pachyptila). Journal of the South Australian Museum 18: 91–121.
Dilley BJ. 2018. The effects of introduced mice on seabirds breeding at sub-Antarctic Islands. PhD thesis: University of Cape Town.
Dilley BJ, Schramm M, Ryan PG. 2017. Modest increases in densities of burrow-nesting petrels following the removal of cats (Felis catus) from Marion Island. Polar Biology 40: 625–637.
Gartshore NA, Steele WK, Klages NT. 1988. Summer diet of the Salvin’s prion at Subantarctic Marion Island. South African Journal of Zoology 23: 309–313.
Hunter S, Brooke MDL. 1992. The diet of giant petrels Macronectes spp. at Marion Island, southern Indian Ocean. Colonial Waterbirds 15: 56–65.
Jones CW, Risi MM, Cooper J. 2019. An incubating northern giant petrel actively feeds on a Salvin’s prion. Antarctic Science 31(6): 317–318.
Jouventin P, Stahl J, Weimerskirch H, Mougin J. 1984. The seabirds of the French subantarctic islands and Adelie Land, their status and conservation. In: Croxall JP, Evans PGH, Schreiber RW (eds), Status and conservation of the world’s seabirds. Cambridge, United Kingdom: International Council for Bird Preservation. pp 609–625.
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.
Onley D, Scofield P. 2007. Albatrosses, Petrels and Shearwaters of the World. London, United Kingdom: A&C Black.
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.
Roman L, Hardesty BD, Hindell MA, Wilcox C. 2019. A quantitative analysis linking seabird mortality and marine debris ingestion. Scientific Reports 9: 3202.
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. 2005. Salvin’s Prion Pachyptila salvini. 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 664.
Schramm M. 1986. Burrow densities and nest site preferences of petrels (Procellariidae) at the Prince Edwards Islands. Polar Biology 6: 63–70.
Sinclair JC. 1980. Subantarctic Skua Catharacta antarctica predation techniques on land and at sea. Cormorant 8: 3–6.
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.
Citation
Banda S 2025. Salvin’s Prion. 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/salvins-prion/
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