Feeding experience and relative size modify the begging strategies of nestlings

Abstract

The offspring of birds and mammals use a combination of movements and vocalizations, known as begging, to solicit food from their parents. A widespread interpretation of begging is that it constitutes an honest signal of offspring need. But we know that in the house sparrow (Passer domesticus) the intensity of begging calls reflects the past experience of offspring in addition to their need. Here we show that this result generalizes to other species. An experiment with hand-reared magpies (Pica pica) and great spotted cuckoos (Clamator glandarius) indicates that the begging strategies depend on the past experience of chicks and the composition of their brood. In asynchronous two-magpie broods, both chicks begged at the same intensity when the large chick obtained food more easily than its sibling, but the large chick begged at higher intensity when it was easier for the smaller chick to obtain food. Cuckoo chicks begged at higher intensity than magpies.