Un outil pour identifier les Laridés adultes : la « Kodak Gray Scale »

The shade of gray across the back and upper wings of adult gulls can be one of the main identification features for these species, however, due to different environmental (conditions of lightning, position of the bird, …) or physiological (wear of feathers, molt, …) factors, it may be difficult to use it in the field. The Kodak Gray Scale is a standard reference for describing and comparing gray tones with some degree consistency that is often been used for gulls identification. It is a quality control device that helps compare tone values of reflection copy with its reproduction. Also helps find the correct exposure and processing conditions.
After a synthesis of the potential difficulties in assessing gray tones in the field, we present you how to use the Kodak Gray Scale and propose you a scheme of the different taxa that can be watched in Western Europe presenting them under the scale with their typical scores.