Begging behaviour and its energetic cost in great spotted cuckoo and magpie host chicks

Abstract

Begging is one of the main factors governing food delivery to chicks by adult birds and it is of great importance in studies of biological communication theory. Many theoretical models have been proposed to explain the evolution of this noisy and conspicuous behaviour, all of which assume that begging activity is energetically costly. We show that both great spotted cuckoo (Clamator glandarius) brood-parasitic chicks and magpie (Pica pica) host chicks ceased to beg after ingesting enough food, and that great spotted cuckoo chicks emitted more begging calls and begged for much longer than did magpie chicks. Using the doubly labelled water method to measure the daily energy expenditure of begging and nonbegging chicks in the laboratory, we show that begging behaviour consumes only a small quantity of oxygen compared with other avian activities usually assumed to be energetically costly.