Begging duration as a potential indicator of nestling condition in first and second broods of European starlings (Sturnus vulgaris)

Abstract

Begging in passerine birds is an honest signal of nestling hunger to the parents. Over the breeding season a decrease in food availability and parental provisioning and an increase in parasite abundance occur suggestive of a decline in brood condition. The purpose of this study was to examine if there is a relationship between begging duration and nestling condition in European starlings (Sturnus vulgaris). Females lay two clutches over the breeding season, and both males and females incubate the eggs and provision the offspring. Nestboxes were checked daily for eggs. Upon hatching, a microphone was placed within the nestbox to record begging vocalizations. Begging was analyzed when nestlings were 11 days of age, which is mid-­‐way through the nestling period. Begging duration did not differ between first and second broods. Second broods were in poorer condition than first broods. Second broods with more nestlings were in significantly poorer condition than those with fewer nestlings. Although there was a difference in condition between first and second broods, no difference in fledging success was detected. In summary, no significant relationship was observed between either total duration or mean duration of begging and nestling condition, which suggests that nestlings continue to beg for food regardless of their condition. Duration of a call does not differ with nestling condition; however begging is still an honest signal of nestling need because it is costly to produce.