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Abstract

Five hypotheses about relationships between begging rates, feeding rates and other variables were investigated in captive budgerigar nestlings from 23 days post-hatch to fledge date (Period 4). Within families, nestlings that begged more frequently during Period 4 were fed more often by their parents, but there was no indication that nestling weight on day 23 was related to begging rates in the subsequent growth interval. Instead, last-hatched nestlings begged more than their older siblings. Last-hatched nestlings were not “undersized” at the beginning of Period 4 relative to their siblings, and they experienced less competition than their siblings had at comparable ages. Even so, last-hatched budgerigars begged more often, were fed more often and fledged at heavier weights than their older nestmates.

Across families, there was a strong positive relationship between average Period 4 begging rate and average parental feeding rate, but this relationship was much weaker when brood sex ratio was taken into account: female-biased broods had much higher begging and feeding rates than male-biased broods. Brood size was related to begging, with higher ratios of begging to feeding rates for family members than for single nestlings.

Taken together, these results suggest that relationships between feeding and begging behavior in budgerigars are more complex than theoretical models have suggested. More studies of avian begging and feeding patterns are required before we can generalize about the control of parental food allocations in birds.