Evaluate grey tones on photos and including in the field is not always so straitforward, on the following photos is obvious how grey tones seem to change with position, light or even camera
300mm Dslr photo.... 3 different shades of grey with 3 different species, nothing wrong so far.
Compact camera photo + 20-60x 82mm ED2 spotting scope...... now the same Yellow-legged Gull grey tone seems harder to judge from the Lesser black-backeds near.
I must say that in the field the grey tone between the Herring and the Yellow-legs present was not always so obvious to discern, and some care must be taken even in the field, ill birds in poor condition or with weak hormones are prone to some confusion.
So many gulls and only one color ring .............!!!!!!! However GR.AS ringed in Belgium by Eric Stienen, is a regular LBBG at Algés area, so it was nice to see her wintering here again.