YELKOUAN SHEARWATER Puffinus yelkouan

YELKOUAN SHEARWATER Puffinus yelkouan

Mediterranean Shearwater, Levantine Shearwater; Balearic Shearwater (P. y. mauretanicus)
L 30–38 cm, WS 76–89 cm.

IDENTIFICATION 

Medium-sized shearwater with marked geographic variation in appearance. Flight action as Manx (q.v.), but tends to look more ponderous and fluttering (perhaps mainly owing to calm conditions in which it is often seen). Does not often follow ships but scavenges at trawlers. Often forms rafts. Yelkouan Shearwater (nominate race) distinguished from all other species (apart from Manx, Little and Audubon’s, q.v.) by blackish-brown upperparts contrasting sharply with almost wholly white underparts and underwing (latter being dark only on wingtip, trailing edge and band across secondary coverts). 

Differs from very similar Manx in having browner upperparts, some brown on flanks, axillaries and undertail coverts, a diagonal brown band across underwing coverts, shorter tail and deeper-chested appearance (but Manx, especially worn birds, can look brownish above in strong light). Feet are proportionately larger and extend slightly beyond tail, tending to cancel out shorter-tailed appearance at long range. Balearic Shearwater (race mauretanicus) similar to nominate Yelkouan in having browner upperparts, shorter tail and deeper-chested appearance than Manx, but is also somewhat larger with a more attenuated body, longer wings and greater feet projection beyond tail. 

Also has quite variable underpart coloration: some resemble nominate Yelkouan (and thus are rather like Manx below, but with dark flanks, axillaries and undertail coverts and a diagonal dark band across underwing coverts), many differ in having a broad dusky breast band, still others have extensive brownish below and some are all brown apart from some whitish on throat, centre of belly and centre of underwing. Whitish areas are typically tinged dirty buff and boundary between dark and pale areas is diffuse. Feet extend significantly beyond tail tip, thus tending to cancel out shortertailed appearance than in Manx. Distant pale mauretanicus could be confused with Cory’s (q.v.), while darkest could be confused with Sooty (q.v.).

VOICE 

On breeding grounds voice apparently rather similar to Manx (q.v.). Usually silent at sea.

TAXONOMY W 

Mediterranean form mauretanicus is probably best treated as a full species, Balearic Shearwater. Previously, both forms were lumped in Manx Shearwater P. puffinus.

GEOGRAPHICAL VARIATION 

Marked. 2 races (both illustrated). See Identification.