Archived 2019 topic: Tristram’s Storm-petrel (Hydrobates tristrami): revise global status?

BirdLife species factsheet for Tristram’s Storm-petrel

Tristram’s Storm-petrel (Hydrobates tristrami) breeds in the Hawaiian archipelago, on several islets of the Bonin and Izu islands off Japan, and possibly on Midway, Lisianski and Kure in Micronesia (Rauzon et al. 1985, Harrison 1990, Baker et al. 1997, McClelland et al. 2008). The population is estimated to number 20,000 mature individuals (Brooke 2004). The species is marine and pelagic; it only comes ashore at breeding colonies (Carboneras et al. 2019).

The population is suspected to be currently stable. The most serious threat is predation by invasive mammals, which has led to population declines in the past and even local extinctions (Rauzon et al. 1985, Kawakami 2008, Carboneras et al. 2019). Interspecific competition with shearwaters, petrels and albatrosses may affect breeding success of Tristram’s Storm-petrel (Fefer et al. 1984, McClelland et al. 2008, Carboneras et al. 2019). Further potential threats include human disturbance, marine pollution and sea level rise associated with climate change.

Tristram’s Storm-petrel is currently listed as Near Threatened on the IUCN Red List, approaching the threshold for listing as threatened under Criterion D2. However, reviewing our information regarding the geographic range, 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 is thought to be stable. Therefore, Tristram’s Storm-petrel may be listed as Least Concern under Criterion A.

Criterion B – The Extent of Occurrence (EOO) of this species is estimated at 16,300,000 km2. This is far too large to qualify for listing as threatened under Criterion B1 (EOO < 20,000 km2). The Area of Occupancy (AOO) is estimated at 1,280 km2, which meets the threshold for listing as Vulnerable under Criterion B2 (AOO < 2,000 km2). However, to be listed under Criterion B, at least two of three further conditions have to be met.

The species is widely distributed across the Pacific Ocean, where it breeds on several islands in Hawaii and Japan. We can therefore assume that it occurs at >> 10 locations*. Moreover, the species forms just one subpopulation (BirdLife International 2019) and is thus not severely fragmented per IUCN definition (see IUCN Standards and Petitions Subcommittee 2017). Tristram’s Storm-petrel does not meet condition (a). The population is stable and there is no evidence of continuing declines nor extreme fluctuations in EOO, AOO, habitat quality and number of locations. Hence, the species does not meet conditions (b) and (c). Therefore, even though Tristram’s Storm-petrel breeds in a restricted AOO, is does not trigger sufficient conditions for listing as Vulnerable under Criterion B. As such, it may be listed as Least Concern under this criterion.

Criterion C – The population size of Tristram’s Storm-petrel has been estimated at c. 20,000 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 various islands in the Hawaiian archipelago, Bonin and Izu islands and possibly Micronesia. Consequently, its AOO and number of locations* are far too large for listing as threatened under Criterion D2. Therefore, Tristram’s Storm-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 Tristram’s Storm-petrel (Hydrobates tristrami) 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

Baker, P.; Baker, H.; Seto, N. 1997. Tristram’s Storm petrel Oceanodroma tristrami on Midway: a probable breeding record. ‘Elepaio 57: 80.

BirdLife International. 2019. Species factsheet: Hydrobates tristrami. http://www.birdlife.org (Accessed 12 April 2019).

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

Carboneras, C.; Jutglar, F.; de Juana, E.; Kirwan, G. M. 2019. Tristram’s Storm-petrel (Hydrobates tristrami). 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/52597 (Accessed 12 April 2019).

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

Fefer, S. I.; Harrison, C. S.; Naughton, M. B.; Shallenberger, R. J. 1984. Synopsis of results of recent seabird research in the Northwestern Hawaiian Islands. In: Grigg, R. W.; Tanove, K. Y. (eds.). Second Symposium on Resource Investigations in the Northwestern Hawaiian Islands. Honululu, HI, U.S.A.

Harrison, P. 1985. Seabirds: an identification guide. Christopher Helm, London.

Kawakami, K. 2008. Threats to indigenous biota from introduced species on the Bonin Islands, southern Japan. Journal of Disaster Research 13: 174-186.

McClelland, G. T. W.; Jones, I. L.; Lavers, J. L.; Sato, F. 2008. Breeding biology of Tristram’s Storm-petrel Oceanodroma tristrami at French Frigate Shoals and Laysan Island, Northwest Hawaiian Islands. Marine Ornithology 36(2): 175-181.

Rauzon, M. J.; Harrison, C. S.; Conant, S. 1985. The status of the Sooty Storm-petrel in Hawaii. Wilson Bulletin 97: 390-392.

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1 Response to Archived 2019 topic: Tristram’s Storm-petrel (Hydrobates tristrami): revise global status?

  1. 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.