Fruit selection in the olive thrush: The importance of colour

Abstract

Free-living olive thrushes Turdus olivaceus were offered a choice of wild olive Olea africana fruit of four colours, representing four ripeness categories. The thrushes ate mostly black fruit (ripest), followed by maroon (ripe) and olive-coloured (partially ripe) fruit. When riper fruit was unavailable, the thrushes selected more maroon or olive-coloured fruit. Green fruit (unripe) were never eaten, even when these were the only ones available. When offered pieces of dyed pear Pyrus communis, the thrushes preferentially selected orange pieces, followed by red and black pieces. Green pieces were never eaten. The results indicated that olive thrushes selected fruit on the basis of fruit colour, and that colour preferences differed between the two types of fruit offered.