The initial deadline for comments on this topic is 7 April 2014, and is therefore later than for most other topics currently under discussion. However, some elements of this topic remain open (see below).
This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for non-passerines
Lynx Edicions and BirdLife International will soon publish the HBW-BirdLife Illustrated Checklist of the Birds of the World, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist.
The new Checklist will be based on the application of criteria for recognising species limits described by Tobias et al. (2010). Full details of the specific scores and the basis of these for each new taxonomic revision will be provided in the Checklist.
Following publication, an open and transparent mechanism will be established to allow people to comment on the taxonomic revisions or suggest new ones, and provide new information of relevance in order to inform regular updates. We are also actively seeking input via a discussion topic here regarding some potential taxonomic revisions that currently lack sufficient information.
The new Checklist will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List. The taxonomic changes that will appear in volume 1 of the checklist (for non-passerines) will begin to be incorporated into the 2014 Red List update, with the remainder, and those for passerines (which will appear in volume 2 of the checklist), to be incorporated into subsequent Red List updates.
Preliminary Red List assessments have been carried out for the newly split or lumped taxa. We are now requesting comments and feedback on these preliminary assessments.
BirdLife’s taxonomic treatment of the Little Shearwater Puffinus assimilis/Audubon’s Shearwater P. lherminieri complex is being revised to reflect improved understanding of their taxonomy, and P. bryani (Pyle et al. 2011) is to be recognised as a species.
P. lherminieri will be provisionally listed as Least Concern in the 2014 Red List update; however, this discussion remains open for comments, with an updated date of posting to enable a potential reassessment of the species as part of the 2017 Red List update.
Prior to this taxonomic change, both P. assimilis (BirdLife species factsheet) and P. lherminieri (BirdLife species factsheet) were listed as being of Least Concern, on the basis that they were not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria.
The following species arrangement is to be adopted by BirdLife for taxa in this complex:
Subantarctic Shearwater P. elegans: Breeds in the Chatham Islands, Antipodes Island, Gough Island and Tristan da Cunha group; at-sea range around New Zealand, South Atlantic Ocean and in the Pacific Ocean off the coast of Chile (Onley and Scofield 2007).
Little Shearwater P. assimilis, including P. a. assimilis, P. a. kermadecensis, P. a. haurakiensis and P. a. tunneyi: Breeds on islands in the Norfolk group, Lord Howe group and Kermadec group, and on seven island groups along the north-eastern coast of North Island, New Zealand, as well as Amsterdam Island, St Paul Island and islands off Western Australia; at-sea range around Australia and New Zealand, to central-southern Indian Ocean (Onley and Scofield 2007).
Audubon’s Shearwater P. lherminieri, including P. l. lherminieri, P. l. baroli and P. l. boydi: Breeds on islands in the north-eastern Atlantic (e.g. Azores, Madeira, Canary Islands, Cape Verde Islands) and in the Caribbean and western Atlantic; at-sea range thought to cover north-western and north-eastern Atlantic Ocean and Caribbean Sea (see Onley and Scofield 2007).
Bonin Shearwater P. bannermani: Breeds in the Ogasawara group; at-sea range thought to be fairly local to these islands (Onley and Scofield 2007).
Arabian Shearwater P. persicus, including P. p. persicus and P. p. temptator: Breeds at least on the Halaaniyaat Islands (Oman), Socotra group (Yemen) and Moheli Island (Comoros); at-sea range covering eastern Persian Gulf, Gulf of Oman, Arabian Sea, Gulf of Aden, southern Red Sea and around the Comoros Islands (Onley and Scofield 2007).
Tropical Shearwater P. bailloni, including P. b. bailloni and P. b. dichrous: Breeds on many widely scattered island groups in the Indian Ocean and Pacific Ocean; at sea, ranges widely in these regions (Onley and Scofield 2007).
Galapagos Shearwater P. subalaris: Endemic breeder on the Galapagos Islands; at-sea range thought to be fairly local to breeding range, but may disperse as far north as the coast of Mexican (Onley and Scofield 2007).
Newell’s Shearwater P. newelli (no change to taxonomic treatment by BirdLife and including P. n. newelli and P. n. myrtae): Breeds in the Hawaiian Islands; at-sea range in the central Tropical Pacific Ocean (Onley and Scofield 2007).
Townsend’s Shearwater P. auricularis (no change to taxonomic treatment by BirdLife): Breeds on Clarión, San Benedicto and Socorro Islands (Mexico); at-sea range along western coast of Mexico and Central America, from Baja California to El Salvador (Onley and Scofield 2007).
Heinroth’s Shearwater P. heinrothi (no change to taxonomic treatment by BirdLife): Distributed in Bougainville and Solomons group.
Bryan’s Shearwater P. bryani: Appears to breed primarily in the Bonin Islands (Kawakami et al. 2012) and range as far east as the north-western Hawaiian Islands, where it may breed occasionally (Pyle et al. 2011).
Implications of altered taxonomic treatments for Red List assessments:
P. bannermani is little-known and its population size has apparently not been estimated. It may nest on only a few islands, with its likely Area of Occupancy (AOO) estimated at c.95 km2, potentially meeting the threshold for Endangered under B2. However, information is needed on threats and trends in the species’s range, habitat and population, in order for a Red List assessment to be attempted. What little information is available suggests that it could be threatened. If there is insufficient information for a robust assessment to be carried out, the species may be listed as Data Deficient.
P. assimilis , P. elegans and P. subalaris all have moderate to large populations, with an apparent minimum (P. subalaris) of c.10,000 pairs (probably equivalent to at least 20,000 mature individuals) (Brooke 2004). It is thus unlikely that any of these species approach the thresholds for Vulnerable under the population size criterion. They may, however, qualify as Near Threatened or Vulnerable under criterion A, if there is evidence of a moderately rapid or rapid population decline, estimated, projected or suspected over three generations in the past, future or both.
All three of these species (P. assimilis, P.elegans, and P. subalaris) appear to be affected by introduced predators, which could be driving declines. The three-generation trend period for these species is thought to be c.54 years (based on an estimated generation length of 18 years for P. assimilis [prior to the taxonomic change] and P.auricularis, the latter of which is thought to be very closely related to P. subalaris [see Onley and Scofield 2007]). Further information is required on whether, over this trend period, these species could be undergoing declines approaching 30%, potentially qualifying them as Near Threatened, and whether they could be declining by 30-49%, which would qualify them as Vulnerable.
In addition, P. elegans has an estimated AOO of 211 km2, potentially qualifying it as Endangered under B2, and P. subalaris has an AOO of c.1,867 km2, potentially meeting the thresholds for Vulnerable under B2. However, they would only be eligible for listing under B2 if it were shown that their breeding range was severely fragmented or restricted to fewer than 11 locations, and that their ranges and/or populations were undergoing continuing declines. Further information is sought, especially on threats and likely population trends.
P. bailloni, P. lherminieri and P. persicus may all warrant listing as being of Least Concern, on the basis that they are not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria. These species are estimated to have moderate to very large breeding ranges and populations, the trends of which may not exceed moderate declines (see Brooke 2004).
Evidence suggests that some breeding populations of P. lherminieri baroli (formerly treated as P. assimilis baroli) are in decline or have been in recent years, whilst other breeding populations appear to have been stable (e.g. BirdLife International 2004, Trujillo and Ramos 2004); however, further information is requested regarding these populations and from across the range of P. lherminieri (as defined following the taxonomic change), as well as for P. bailloni and P. persicus.
P. bryani was described in 2011 on the basis of a single specimen collected on Midway Atoll in 1963, with another individual probably of this species observed on Midway in 1991-1992; however, the species is not thought to breed regularly in the north-western Hawaiian Islands (Pyle et al. 2011). Subsequent analysis of specimens from the Bonin Islands suggests that its main breeding range is within that group, although much exploration is still to be done (Kawakami et al. 2012). The species may be threatened, as there is evidence that it is predated by introduced rats, and it appears to be rare, thus it has been surmised that it has an extremely small population (Kawakami et al. 2012). Rats were eradicated on Higashijima in 2008-2009, following an event of mass predation on seabirds, but despite eradication being pursued on other islands, there are still more than 20 islands in the Bonin group that are inhabited by introduced rats (Kawakami et al. 2012).
Although P. bryani is likely to have a small to extremely small population and can be inferred to be in continuing decline owing to the impacts of introduced predators, relevant advances in taxonomic understanding and identification have only been very recent, thus it may not be appropriate to estimate its population and range size based on current knowledge. It may be appropriate to list the species as Data Deficient, if there is thought to be insufficient information available for a robust Red List assessment to be carried out.
Comments are invited and further information would be welcomed.
BirdLife International (2004) Birds in Europe: population estimates, trends and conservation status. Cambridge, UK: BirdLife International (BirdLife Conservation Series 12).
Brooke, M. De L. (2004) Albatrosses and petrels across the world. Oxford, UK: Oxford University Press.
Kawakami, K., Eda, M., Horikoshi, K., Suzuki, H., Chiba, H. and Hiraoka, T. (2012) Bryan’s shearwaters have survived on the Bonin Islands, northwestern Pacific. Condor 114: 507–512.
Onley, D. and Scofield, P. (2007) Field guide to the albatrosses, petrels and shearwaters of the world. London, UK: Christopher Helm (Helm Field Guides).
Pyle, P., Welch, A. J. and Fleischer, R. C. (2011) A new species of shearwater (Puffinus) recorded from Midway Atoll, northwestern Hawaiian Islands. Condor 113: 518–527.
Tobias, J. A., Seddon, N., Spottiswoode, C. N., Pilgrim, J. D., Fishpool, L. D. C. and Collar, N. J. (2010) Quantitative criteria for species delimitation. Ibis 152: 724–746.
Trujillo, D. and Ramos, J. J. (2004) Pardela Chica Puffinus assimilis baroli. Pp 51–53 in Madroño, A., González, C. and Atienza, J. C. (Eds.) Libro Rojo de las Aves de España. Madrid, Spain: Dirección General para la Biodiversidad-SEO/BirdLife.