The shearwater problem in the Mediterranean (II)

8 01 2012

The other species of shearwater breeding in the Mediterranean is the Scopoli’s shearwater (Calonectris diomedea diomedea), formerly known as Cory’s shearwater. The split between Cory’s (nowadays the name of the atlantic subspecies borealis) and Scopoli’s is close to be admited by all the taxonomic comitees. The morphologycal differences are quite visible in the field and some catalan observers are already waiting for the first Cory’s for Catalonia.

However, Martínez-Abrain et al 2002 suggested that there are some Cory’s shearwater breeding in the Columbretes islands, in the Mediterranean sea, although there is not data enough to evaluate the genetic flow between both subspecies. As in the case of the Mediterranean shearwaters of Menorca, that rebel birds can explain the intergrades easyly observed when looking for a pure Cory’s in the Mediterranean or a pure Scopoli’s in the Atlantic. The first 4 pictures have been taken in the Mediterranean, in front of Valencia and show the diversity among mediterranean birds. The other pictures are from the Atlantic

Picture 1: This bird must be a pure Cory’s in my opinion. All the primaries are black in the underwing and the bill looks so thick, despite that character is difficult to judge in the field.Picture 2: Another pure bird in my opinion. The dark in the underwing coverts points to Cory’s. The primaries are completely dark again.Picture 3: Unidetified shearwater. The is a long white tongue in p4 and a short one in p5.Picture 4: Another individual with mixed characters. It has a long tongue in p4 again, and 3 short tongues in p3 and p5. Note the dark marking in underwing coverts, good for Cory’s.Picture 5: A pure Scopoli’s outside the Mediterranean. Some of them were leaving it during november and the Gulf of Cádiz is a good stopover to take profit of the fishery.Picture 6: Another pure Scopoli’s in the Gulf od Cádiz. Note that, apart from the white tongues of the primaries, there is no dark marking in the underwing (also in picture 5).Picture 7: The opposite from pictures 5 and 6. A pure Cory’s in the Galicia Bank (120 mn off Galicia) with extremely dark marking in the axillaries. Of course primaries are all black.




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