A method for color-marking birds at resting sites

A short-term color-marking technique suitable for non-breeding birds was developed by altering a common method used to mark incubating birds. A dye paste was spread on the ground at resting sites used by Herring (Larus argentatus) and Great Black-backed (L. marinus) gulls. Gulls first contacted dye by walking, standing, or sitting in the paste. When preening, birds transferred small amounts of dye over their feathers, creating unique patterns. Marks remained visible an average of 27 d.