THE FUNCTION OF BILL-WIPING

Three experiments were performed on captive European starlings, Sturnus vulgaris, to investigate the function of bill-wiping. The common-sense view, that wiping serves primarily to clean the bill, was confirmed experimentally: wiping frequency was adjusted to food 'stickiness' and the suitability of perches for cleaning. However, by manipulating the degree of abrasion from perches, wiping was also shown to have a significant effect on mandible length and overlap, which in turn affected handling efficiency in certain foraging tasks. Birds with reduced abrasion from wiping showed compensatory increases in wiping frequency as their beaks grew. This lends support to the idea that wiping frequency may be strategically adjusted to tune bill shape to current diet. © 1992 The Association for the Study of Animal Behaviour.