Early-life begging effort reduces adult body mass but strengthens behavioural defence of the rate of energy intake in European starlings

Citation

Dunn J, Andrews C, Nettle D & Bateson M (2018) Early-life begging effort reduces adult body mass but strengthens behavioural defence of the rate of energy intake in European starlings. Royal Society Open Science, 5 (5), p. 171918. https://doi.org/10.1098/rsos.171918

Abstract
Animals require strategies for coping with periods when food is scarce. Such strategies include storing fat as a buffer, and defending the rate of energy intake by changing foraging behaviour when food becomes difficult to obtain. Storage and behavioural defence may constitute alternative strategies for solving the same problem. We would thus expect any developmental influences that limit fat storage in adulthood to also induce a compensatory alteration in adult foraging behaviour, specifically when food is hard to obtain. In a cohort of hand-reared European starlings, we found that higher manipulated early-life begging effort caused individuals to maintain consistently lower adult body mass over a period of two years. Using an operant foraging task in which we systematically varied the costs of obtaining food, we show that higher early-life begging effort also caused stronger behavioural defence of the rate of energy intake when food was more costly to obtain. Among individuals with the same developmental history, however, those individuals who defended their rate of energy intake most strongly were also the heaviest. Our results are relevant to understanding why there are marked differences in body weight and foraging behaviour even among individuals inhabiting the same environment.

Keywords
early-life adversity; body mass; Sturnus vulgaris; foraging behaviour; energy intake; begging

Journal
Royal Society Open Science: Volume 5, Issue 5