The use of a colorimeter in field studies of Blue Tit Parus caeruleus coloration

We tested the use of a field colorimeter for studying plumage coloration of three species of small passerines in the field. Measurement repeatability was generally high, although for some species some parts of the plumage pro ved difficult to measure accurately. As an example, we showed that plumage coloration of the Blue Tit Parus caeruleus varied among sites, sexes and ag e classes. Using a discriminant function, which was based on various plumag e colour measurements, we were able to sex more than 96% of all individuals correctly. In conclusion, colorimeters provide a reliable method to quanti fy plumage coloration.