Scopoli's Shearwater: first for Britain

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Bob Flood and Ashley Fisher

On the evening of 2 August 2004 we were on board MV Sapphire six miles south of St Mary’s with John Higginson, Bryan Thomas, and two other birders. At 20.03 a seabird appeared from the west directly in-line with the setting sun. First sightings thus were in silhouette. Bryan Thomas initially called it as a gull. John Higginson then called it as a Great Shearwater before correcting himself when plumage became visible, calling Cory’s Shearwater. This sequence of calls is significant because based on structure only when in silhouette both Bryan and John called species much slimmer than Cory’s.

The seabird was indeed a Calonectris shearwater. It approached starboard side and at about 30 metres banked to our left heading off past the bow. We scrutinised the underwing looking for what is the only diagnostic field characteristic that separates Scopoli’s from Cory’s – the former with dark bordered white inner webbings to the primaries. EAF momentarily thought he saw the Scopoli’s pattern. Although we were concentrating on the underwing pattern, we did register a slim bill, head and body. The shearwater then banked right 180 degrees and flew back alongside the boat at about 40 metres, moving directly in-line with the sun, before banking left once again. We continued to grill the underwing, but were severely hindered by the harsh light conditions. The pattern as far as we could see seemed to ghost that of Cory’s and it was this appearance that swayed thinking away from Scopoli’s. The shearwater then gracefully flew away in a south-westerly direction. Without a photographer on board that would have been that!

Meanwhile, Bryan Thomas managed to take a short series of seven digital photographs each with six million pixels of information, the first to last being separated by just 80 seconds (the duration of the event). Bryan’s digital photography drew features of the bird out of the harsh light conditions and revealed the diagnostic underwing pattern as well as important structural characteristics. Bryan emailed one image to RLF. With the image on computer screen, RLF was able to identify the shearwater as a Scopoli’s based on the underwing pattern and forwarded them on to EAF for additional confirmation. Further scrutiny confirmed that the bill, head and body were noticeably slimmer than Cory’s, as expected with a Scopoli’s. Cape Verde Shearwater was eliminated since amongst other things it shows a Cory’s underwing and an essentially grey rather than, as in this case, a yellowish bill.

Scopoli's Shearwater © Bryan Thomas General Impression: In many respects like a slim Cory’s Shearwater, with greyer head plumage and faster flight action.

Structure: A large shearwater, in general structured like a Cory’s Shearwater with long bowed wings. However, bill, head and body thought to be slimmer than Cory’s in the field.  Photographs prove bill head and body were obviously slimmer than Cory’s. Note that Cory’s averages 46% heavier than Scopoli’s.

Plumage: Head, neck and sides of breast, mantle and back: Milky chocolate brown, but paler and perhaps greyer than is normal in Cory’s. Rump: Coloured as mantle and back, but with white U-shape pattern at base of tail. Underparts: White. Upperwing: Primaries and secondaries dark brown. Coverts paler brown, but not as pale as mantle and back, with dark band diagonally across the arm Underwing: Thin brown leading edge. Coverts white. Secondaries and primaries brown save for the following; dark bordered white inner webbings to the primaries giving the impression of white ‘fingers’ extending along the primaries beyond the underwing coverts – diagnostic of Scopoli’s and obvious in photographs of the bird. Richard Gutiérez commented that the underwing pattern does not vary geographically. Killian Mullarney and others commented that Cory’s sometimes show a suggestion of short white ‘fingers’ penetrating the dark of the primaries, but not extensively as in our bird. Tail: Dark brown.

Bill: Slim relative to Cory’s, yellowish with dark end; perhaps not as yellow as Cory’s.

Eye: Small, black, positioned central front of head, just higher than bill.

Legs: Barely visible completely tucked underneath tail.

Flight: Similar to Cory’s, but less languid with somewhat faster wing beats making the bird ‘feel’ different from Cory’s, which often we see in similar circumstances. Flight expected to be noticeably different than Cory’s given structural differences.

Accepted to sub-species (diomedea) by BOURC and admitted to the Brittish List as the first confirmed record. See BOURC: 37th Report (October 2008).

Bibliography
Beaman, M., and Madge, S. 1998. The Handbook of Bird Identification for Europe and the Western Palearctic, Helm, London.
Camphuyse, C.J. and van der Meer, J. 2001. Pelagic distribution, moult and (sub-) specific status of Cory’s Shearwaters Calonectris [d.] diomedea/borealis wintering off southern Africa. Marine Ornithology 29: 89-96.
Gutiérrez, R. 1998. Flight identification of Cory’s and Scopoli’s Shearwaters. Dutch Birding 20: 216-225.
Howell, S. and Patteson, B. J. 2008. Variation in Cory's and Scopoli's Shearwaters. Alula 1: 12-21.
Madge, S. 2003. Three of a kind. Birdwatch July: 22-25.
Porter, R., Newell, D., Marr, T., and Jolliffe, R. 1997. Identification of Cape Verde Shearwater. Birding World 10: 222-228.
Sibley, D. 2000. The North American Fieldguide, Pica Press, Sussex.