During winter Crested Pigeons Ocyphaps lophotes and Spotted Turtle-Doves Streptopelia
chinensis often develop dark-brownish plumage in suburban Adelaide. Up to 80 per cent of pigeons
and doves censused in the Gilberton area developed darker plumage. This darkening coincided with
the presence of European olives Olea europea in the birds' diets. We argue that these pigeons and
doves splash olive oil and an associated dark-purplish pigment onto their feathers while tearing
chunks of mesocarp from fallen olives. Captive birds fed on a diet that included ripe olives developed
the dark plumage while birds fed only on grain did not. Birds fed mainly on olives also lost weight.
