Archived 2019 topic: Murphy’s Petrel (Pterodroma ultima): revise global status?

BirdLife species factsheet for Murphy’s Petrel

Murphy’s Petrel (Pterodroma ultima) occurs in the south-central Pacific Ocean, where it breeds on Pitcairn, the Tuamotu Archipelago, the Austral Islands, Easter Island as well as in French Polynesia, and possibly also on the Cook and Juan Fernandez islands (Garnett 1984, Thibault and Bretagnolle 1999, Flores et al. 2014, Flood et al. 2016). The population is estimated at 800,000-1,000,000 mature individuals (Brooke 2004). The species is marine and pelagic; it only comes ashore at breeding colonies (Carboneras et al. 2019). There is no data on the population trend; however, the species is presumably in slow decline due to predation of eggs and fledglings by rats. A further potential threat is sea-level rise associated with climate change.

Murphy’s Petrel is currently listed as Near Threatened on the IUCN Red List, approaching the threshold for listing as threatened under Criteria A2e+3e+4e. However, reviewing our information regarding the population trend, this species appears to warrant a change in Red List status. Therefore, we present here our reassessment against all criteria for the species.

Criterion A – The population trend has not been estimated. However, the species is thought to be in decline due to predation by invasive species. The rate of decline is suspected to be at 1-19% over three generations, which is too low to meet or approach the threshold for Vulnerable under Criterion A (≥ 30% over three generations). Therefore, Murphy’s Petrel may be listed as Least Concern under this criterion.

Criterion B – The Extent of Occurrence (EOO) of this species is estimated at 69,000,000 km2. This is far too large to qualify for listing as threatened under Criterion B1 (EOO < 20,000 km2). The Area of Occupancy (AOO) has not been quantified, and the species cannot be assessed against Criterion B2. Therefore overall, the species may be considered Least Concern under Criterion B.

Criterion C – The population size of Murphy’s Petrel has been estimated at800,000-1,000,000 mature individuals. This is too large to meet the threshold for qualifying as threatened under Criterion C (< 10,000 mature individuals). Therefore, the species may be listed as Least Concern under this criterion.

Criterion D – The population size of this species is far too large to qualify for listing as threatened under Criterion D1. Moreover, it breeds on a high number of islands in the Pacific Ocean. Consequently, while the AOO has not been quantified, the number of locations* of occurrence is far too large for listing as threatened under Criterion D2. Therefore, Murphy’s Petrel may be considered Least Concern under Criterion D.

Criterion E – To the best of our knowledge no quantitative analysis of extinction risk has been conducted for this species. Therefore, it cannot be assessed against this criterion.

Therefore, it is proposed that Murphy’s Petrel (Pterodroma ultima) be listed as Least Concern. We welcome any comments on this proposed listing.

Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of its Red List status. Therefore, please make sure your comments are relevant to the discussion outlined in the topic.

*The term ‘location’ refers to a distinct area in which a single threatening event can rapidly affect all individuals of the taxon present, with the size of the location depending on the area covered by the threatening event. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat (IUCN 2001, 2012).

An information booklet on the Red List Categories and Criteria can be downloaded here and the Red List Criteria Summary Sheet can be downloaded here. Detailed guidance on IUCN Red List terms and definitions and the application of the Red List Categories and Criteria can be downloaded here.

References

Brooke, M. de L. 2004. Albatrosses and Petrels Across the World. Oxford University Press, Oxford.

Carboneras, C.; Jutglar, F.; Kirwan, G. M. 2019. Murphy’s Petrel (Pterodroma ultima). In: del Hoyo, J.; Elliott, A.; Sargatal, J.; Christie, D. A.; de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona, Spain. https://www.hbw.com/node/52530 (Accessed 12 April 2019).

Garnett, M. C. 1984. Conservation of seabirds in the South Pacific region: a review. In: Croxall, J. P.; Evans, P. G. H.; Schreiber, R. W. (eds.). Status and conservation of the world’s seabirds, pp. 547-558. International Council for Bird Preservation, Cambridge, U.K.

IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K.

IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1. Second edition. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K. www.iucnredlist.org/technical-documents/categories-and-criteria

Flood, R. L.; Wilson, A .C.; Danzenbaker, M.; Ryan, J.; Shemilt, J.; Zufelt, K. 2016. Three Murphy’s Petrels Pterodroma ultima off the Juan Fernandez Islands, Chile, November 2014. Cotinga 38: 110-112.

Flores, M. A.; Schlatter, R. P.; Hucke-Gaete, R. 2014. Seabirds of Easter Island, Salas y Gomez Island and Desventuradas Islands, southeastern Pacific Ocean. Latin American Journal of Aquatic Research 42(4): 752-759.

Thibault, J.-C.; Bretagnolle, V. 1999. Breeding seabirds of Gambier Islands, Eastern Polynesia: numbers and changes during the 20th century. Emu 99: 100-107.

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3 Responses to Archived 2019 topic: Murphy’s Petrel (Pterodroma ultima): revise global status?

  1. Steffen Oppel says:

    Rat eradication on Ducie and Oeno, which host the largest breeding colonies for this species, were successful in 1997 (Brooke 2019), and the population on Oeno appears to be increasing (Brooke et al. 2018). The fact that rats depredate eggs or chicks at peripheral populations may not affect the global population size very much. Although there are no robust and long-term breeding population data due to the remoteness of all breeding locations, current evidence does not justify that this species is listed as ‘Near Threatened’. The catastrophic predation that is observed on Henderson Island (Churchyard et al. 2013, Lavers et al. 2016) is clearly unsustainable, but may only affect a peripheral sink population that is maintained by individuals colonising from Oeno or Ducie.

    The ‘area of occupancy’ (if this refers only to the small islands where the species breeds?) may however be small enough to meet criterion B, hence it would be useful to calculate area of occupancy.

    References

    Brooke, M.de L., Bonnaud, E., Dilley, B.J. et al. (2018) Seabird population changes following mammal eradications on islands. Animal Conservation, 21, 3-12.

    Brooke, M.de L. (2019) Rat eradication in the Pitcairn Islands, South Pacific: a 25-year perspective. Island invasives: scaling up to meet the challenge (eds C.R. Veitch, M.N. Clout, A.R. Martin, J.C. Russell & C.J. West), pp. 95–99. IUCN, Gland, Switzerland.

    Churchyard, T., Proud, T., Brooke, M.d.L., O’Keefe, S., Warren, P. & Rodden, M. (2013) Henderson Island Trip Report 2013. pp. 38. Royal Society for the Protection of Birds, Sandy, UK.

    Lavers, J.L., McClelland, G.T., MacKinnon, L. et al. (2016) Henderson Island expedition report: May-November 2015. Royal Society for the Protection of Birds, Sandy, UK.

  2. Graeme Taylor says:

    I agree that removing invasive species (Polynesian rats) from two of the major breeding sits has been a game changer for this species. It would be fantastic to have all breeding sites cleared of rats. However the experience we have in New Zealand from related species such as Pterodroma pycrofti is that once the key threat is removed, the species starts to recover quite rapidly and there are now thousands of extra breeding pairs. When rats were present breeding success was as low as 20%. It improved immediately after rat removal to 80%. These birds returned to breed 3-5 years later and the colony started to expand rapidly within a decade. Pterodroma petrels are mostly philopatric to their natal sites but a small percentage (<10%) do shift around to new sites. This emigration outwards from expanding populations will continue to support populations where rats remain a problem for breeding birds. So Least Concern is reasonable based on the large numbers of this species and their diverse breeding range.

  3. Rob Martin (BirdLife International) says:

    Preliminary proposal

    Based on available information, our preliminary proposal for the 2019 Red List would be to adopt the proposed classifications outlined in the initial forum discussion.

    There is now a period for further comments until the final deadline in mid-July, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from those in the initial proposal.

    The final 2019 Red List categories will be published on the BirdLife and IUCN websites in December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

Comments are closed.