Atlantic Yellow-legged Gulls -- Generic Features of Adults (December 2002)
Eight features common to most adult Atlantic Yellow-legged Gulls are given here:
blue-grey mantles, generally brighter blue than those of Mediterranean michahellis which have been thought to be less bluish than fresh argenteus (Grant, 1986; Garner & Quinn, 1997) or a steely or dull grey (Jonsson, 1998).
relatively small size, being 5-10% less than Mediterranean michahellis in the length of wing, bill and tarsus
blunt wingtip giving bunched white tips on the folded wing; P9 is the same length as P10 or very slightly shorter while in Mediterranean michahellis P10 is usually longer; P8 is closer in length to P9 than to P7 while in Mediterranean michahellis the difference between the lengths of P7 and P8 and of P8 and P9 is the same.
short-legs, c70% of body height above legs when perched, compared to Mediterranean michahellis, c100% of body height above legs.
rounded heads, lacking the angular or square appearance of Mediterranean michahellis.
long calls lacking the guttural nature of Mediterranean michahellis; mew calls more like graellsii, less deep than those of Mediterranean michahellis.
head held at angle of 60° in long calls, compared to 90° in Mediterranean michahellis.