The Sargasso shearwater (Puffinus lherminieri) is a small tropical seabird in the petrel family. The only shearwater to nest primarily in the Caribbean, it ranges throughout the western Atlantic during the non-breeding season. Its specific epithet honours the French naturalist Félix Louis L'Herminier.

This bird is part of a species complex formerly known as Audubon's shearwater, or occasionally as dusky-backed shearwater. Most authors now separate this complex into a range of species including the Sargasso shearwater, tropical shearwater, Boyd's shearwater, Barolo shearwater, Bannerman's shearwater, and Persian shearwater. In general appearance, it is a small shearwater, black above and white below and hard to distinguish from its relatives at first glance. Both parents share the responsibility of incubating the single white egg (measurements of 52.5 by 36.2 mm and a weight of 37 g have been recorded for one specimen of average size

Systematics

The Sargasso shearwater belongs to the genus Puffinus of mid-sized and small shearwaters. Within Puffinus, the taxonomy of this species has been convoluted. It has traditionally been considered the nominate subspecies of the larger Audubon's shearwater complex, which included up to 10 subspecies. Although of somewhat limited value in procellariiform birds, analysis of mtDNA cytochrome b sequence data indicated that at least three major clades were distinguished within the traditional "Audubon's shearwater" complex. Following further genomic research, the majority of these taxa are now generally considered to comprise their own species, including Sargasso shearwater.

The lherminieri clade (Atlantic Ocean, Caribbean)

  • Sargasso shearwater, Puffinus lherminieri <small>Lesson, 1839</small> &ndash; breeds throughout the Caribbean, on the Bahamas and formerly on Bermuda; ranges throughout the Caribbean and up the North American Atlantic coast up to southern Canada, with vagrants having been recorded off north-eastern Canada.

The persicus clade (West Indian Ocean)

thumb|Puffinus persicus

  • Persian shearwater, Puffinus persicus <small>Hume, 1837</small> &ndash; breeds on Khuriya Muriya Islands (Arabian Sea); ranges throughout the Arabian Sea.

This group is the most confusing of all. The subspecies dichrous occurs in two areas which appear to be separated by the whole of Indonesia and the seas surrounding it; the Pacific subpopulation includes the proposed subspecies polynesiae (Ta'ū, American Samoa) and possibly gunax (see below), whereas the geographically separated Indian Ocean subpopulation contains the birds formerly separated as nicolae (NW Indian Ocean, from Aldabra to the Maldives) and colstoni (Aldabra, Arabian Sea).

thumb|Tropical shearwater Puffinus bailloni of [[Reunion Island.]]

There appear to be no significant genetical or morphological differences between these birds, which is quite amazing given that the Pacific and Indian Ocean subpopulations must have been isolated for a fairly long time, and that no less than three unequivocally distinct subspecies (bailloni, persicus and temptator) occur within the range of Indian Ocean dichrous. On the other hand, the supposed species Mascarene shearwater (P. atrodorsalis) is inseparable morphologically and genetically from bailloni.

Clearly, some mechanism blocking gene flow is at work, but what this is exactly remains unknown &ndash; though as remarked above, separate breeding seasons seem a reasonable assumption and are tentatively supported by the available field data. been proposed as a distinct species, Bannerman's shearwater (P. bannermani). In the absence of more recent data to investigate this claim, its status continues to be altogether unresolved, though the case for it being at least a distinct subspecies in the bailloni clade seems good.

The little-known Heinroth's shearwater (P. heinrothi) was sometimes considered a subspecies of either the Audubon's or the little shearwater complexes. Its actual relationships remain uncertain due to lack of specimens.

Footnotes

References

  • Austin, Jeremy J. (1996): Molecular Phylogenetics of Puffinus Shearwaters: Preliminary Evidence from Mitochondrial Cytochrome b Gene Sequences. Mol. Phylogenet. Evol. 6(1): 77–88. <small></small> (HTML abstract)
  • Austin, Jeremy J.; Bretagnolle, Vincent & Pasquet, Eric (2004): A global molecular phylogeny of the small Puffinus shearwaters and implications for systematics of the Little-Audubon's Shearwater complex. Auk 121(3): 847–864. <small>DOI: 10.1642/0004-8038(2004)121[0847:AGMPOT]2.0.CO;2</small> HTML abstract HTML fulltext without images
  • Bull, John L.; Farrand, John Jr.; Rayfield, Susan & National Audubon Society (1977): The Audubon Society field guide to North American birds, Eastern Region. Alfred A. Knopf, New York. <small></small><!-- 1984 is reprint -->
  • Carboneras, Carles (1992): 69. Audubon's Shearwater. In: del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (eds.): Handbook of Birds of the World (Vol. 1: Ostrich to Ducks): 256–257, plate 16. Lynx Edicions, Barcelona. <small></small>
  • Efe, Márcio Amorim & Musso, Cesar Meyer (2001): Primeiro registro de Puffinus lherminieri Lesson, 1839 no Brasil [First record of Audubon's Shearwater (Puffinus lherminieri) for Brazil]. Nattereria 2: 21-23 [Portuguese with English abstract]. PDF fulltext
  • Heidrich, Petra; Amengual, José F. & Wink, Michael (1998): Phylogenetic relationships in Mediterranean and North Atlantic shearwaters (Aves: Procellariidae) based on nucleotide sequences of mtDNA. Biochemical Systematics and Ecology 26(2): 145–170. <small></small> PDF fulltext
  • Penhallurick, John & Wink, Michael (2004): Analysis of the taxonomy and nomenclature of the Procellariiformes based on complete nucleotide sequences of the mitochondrial cytochrome b gene. Emu 104(2): 125–147. <small></small> (HTML abstract)
  • Rheindt, F.E. & Austin, Jeremy J. (2005): Major analytical and conceptual shortcomings in a recent taxonomic revision of the Procellariiformes &ndash; A reply to Penhallurick and Wink (2004). Emu 105(2): 181–186. <small></small> PDF fulltext
  • Vaurie, C. (1965): The Birds of the Palearctic Fauna (Vol. 1: Non-Passeriformes). Witherby, London.
  • Wiles, Gary J.; Worthington, David J.; Beck, Robert E. Jr.; Pratt, H. Douglas; Aguon, Celestino F. & Pyle, Robert L. (2000): Noteworthy Bird Records for Micronesia, with a Summary of Raptor Sightings in the Mariana Islands, 1988–1999. Micronesica 32(2): 257–284. PDF fulltext

Further reading

  • Snow, D.W. (1965). "The breeding of the Audubon's Shearwater Puffinus lherminieri in the Galapagos." The Auk 82(4)