The effect of learning on nestling begging strategies: A test with hand-raised house sparrows

Parent birds provide food to their young in response to begging. A nestling's probability of being fed is affected by its relative size and ability to compete for a favorable position in the nest. If begging success varies among broodmates, it might be adaptive for nestlings to learn to beg at the level that rewards them most effectively. In this study, we attempted to test the role of learning in the development of begging strategies. Twenty pairs of house-sparrow nestlings were hand-raised in the laboratory for 3 consecutive days. Throughout the day, we stimulated the nestlings to beg, and fed them in response to their begging. In each pair of nestlings, one nestling was fed immediately, while the second was fed only if it begged intensively. The results show that the nestlings of the second group developed a more intensive begging strategy. The amounts of food, the daily feeding schedule, and the growth rate of both groups were similar, indicating that the differences in begging were a result of learning rather than physiological differences. This is the first experimental evidence that learning affects the development of begging strategies. It suggests that begging may not only signal offspring need, but may also reflect past experience and family dynamics.