Selective Predation by White-Tailed Black Cockatoos on Fruit of Banksia Attenuata Containing the Seed-Eating Weevil Alphitopis Nivea.

Abstract

The cockatoo Calyptorhynchus funereus latirostris excavates the seed-eating weevil Alphitopis nivea from young fruits of Banksia attenuata trees but discards the immature seed. The birds attacked similar proportions of trees in 3 nearby areas that differed, due to previous histories of fires, in number of reproductive structures per tree. However, within areas the cockatoos attacked trees with larger numbers of fruits. In addition, the proportion of fruits containing weevils was greater in those fruits that the cockatoos attacked than in those they did not. The weevils mostly occurred in larger fruits and large size could be a clue enabling selection of fruits by the birds. The birds removed between 1 and 2 weevils per fruit, but if the weevils were absent the birds still destroyed follicles and often the whole fruit.