Western Straits of Gibraltar (Spain) (michahellis)

Mantle: most are a similar blue-grey to that of the Dark form.

Size: larger than the Dark form, being significantly bigger than graellsii but obviously smaller than Mediterranean Yellow-legged Gull in direct comparison

Primaries: similar to the Dark form with only 20% of adults showing a mirror on P9.

Calls: long calls are predominantly of the shrill graellsii type (57%) with some deep argenteus (21%) and deep guttural graellsii (21%), the latter being assigned to adults looking in all respects like Mediterranean Yellow-legged Gull. Mew calls are very much (90%) like graellsii except for a small number (10%) like deep graellsii, assigned to Mediterranean Yellow-legged Gull.

Moult in adults: almost identical to that found in Estepona, Tanger and Cádiz in the same visit.

First-years: They seem to invariably show white upper tails and as many as 50% show a white head rather than a dusky one. 30-45% show heavy streaking on the breast and belly, similar to the position in Gibraltar. One showed tertials with a broad white fringe and large pale tip.

Comments: the gulls did not follow the Tarifa-Tanger ferry across the Straits but 1/3rd of the way over from Tarifa there were some Mediterranean Yellow-legged Gull types (all ages) feeding on the water.