Bestaat er bij Wespendieven Pernis apivorus een relatie tussen de mate van pigmentatie en de positie van jongen op hetzelfde nest?

In two closely observed nests of Honey-buzzards in the southern Netherlands, the oldest of two chicks had a light plumage, the second chick a darker plumage. Differences in coloration were particularly evident in the feathers of the head. Observers are asked to collect material on plumage colouration in Honey-buzzard chicks of known rank within nests.