The Little Shearwater (Puffinus assimilis) is a small shearwater in the petrel family Procellariidae. Despite the generic name, it is unrelated to the puffins, which are auks, the only similarity being that they are both burrow-nesting seabirds.

Description

This shearwater has the typically "shearing" flight of the genus, dipping from side to side on stiff wings with few beats, the wingtips almost touching the water, though in light winds it has a more flapping flight than than that of its larger relatives. In flight it looks cross-shaped, with its wings held at right angles to the body, its colouration changing from black to white as the black upperparts and white underparts are alternately exposed as it travels low over the sea.

At 25–30 cm (9.8–12 in) in length with a 58–67 cm (23–26 in) wingspan, it is like a small Manx Shearwater but has proportionally shorter and broader wings, with a pale area on the inner flight feathers. Its bill is more slender than that of Manx, and its dark eye stands out against the surrounding white area.

Taxonomy

mtDNA cytochrome b sequence data indicate that the former North Atlantic Little Shearwater group (Boyd's Shearwater, P. boydi and Barolo Shearwater, P. baroli) is closer to Audubon's Shearwater (Austin 1996, Heidrich et al. 1998), (although many taxonomists now consider them to be distinct species), and myrtae being closer to the Newell's and possibly Townsend's Shearwater (Austin et al. 2004). Heinroth's Shearwater was also sometimes considered a subspecies of this bird; the relationship between the Little and Audubon's Shearwater is probably not as close as long believed (Austin 1996, Heidrich et al. 1998, Austin et al. 2001, but see also Penhallurick & Wink 2004, and Rheindt & Austin 2005).

Distribution and habitat

This species occurs throughout the oceans of the Southern Hemisphere south of the Tropic of Capricorn. It breeds in colonies on islands and coastal cliffs, nesting in burrows which are only visited at night to avoid predation by large gulls.

Behaviour

This is a gregarious species, which can been seen in large numbers from boats or headlands, especially on passage in autumn. It feeds on fish and molluscs. It does not follow boats. It is silent at sea, but at night the breeding colonies are alive with raucous cackling calls.

References

• Austin, Jeremy J. (1996): Molecular Phylogenetics of Puffinus Shearwaters: Preliminary Evidence from Mitochondrial Cytochrome b Gene Sequences. Molecular Phylogenetics and Evolution 6(1): 77–88. doi:10.1006/mpev.1996.0060 (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. DOI: 10.1642/0004-8038(2004)121[0847:AGMPOT]2.0.CO;2 HTML abstract

• BirdLife International (2004). Puffinus assimilis. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 12 May 2006. Database entry includes justification for why this species is of least concern

• Collinson, M. (2006): Splitting headaches? Recent taxonomic changes affecting the British and Western Palaearctic lists. British Birds 99(6): 306-323.

• 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. doi:10.1016/S0305-1978(97)00085-9 PDF fulltext

• Penhallurick, John & Wink, Michael (2004): Analysis of the taxonomy and nomenclature of the Procellariformes based on complete nucleotide sequences of the mitochondrial cytochrome b gene. Emu 104(2): 125-147. doi:10.1071/MU01060 (HTML abstract)

• Rheindt, F. E. & Austin, Jeremy J. (2005): Major analytical and conceptual shortcomings in a recent taxonomic revision of the Procellariiformes - A reply to Penhallurick and Wink (2004). Emu 105(2): 181-186. doi:10.1071/MU04039 PDF fulltext