Magpie (Pica pica) Science Article 2
We investigated whether an increase in begging levels delays growth of chicks. In experiment 1, we hand-reared nine pairs ofring dove squabs, divided into a control and a begging group. All squabs received similar amounts of food, but those in thebegging group had to beg for a prolonged period in order to be fed, while squabs in the control group received food withoutbegging. Squabs stopped responding to the treatment after 10 days and, at that time, there was no effect of induced beggingon their body mass. In experiment 2, we hand-reared 27 pairs of magpie chicks for 3 days. The design of experiment 2 wassimilar to that of experiment 1. Daily food intake and begging affected growth rates. On average, chicks in the begging groupgrew 0.8 g/day less than control chicks, which represents a decrease of 8.15% in growth rate. Because growth is usually positivelyassociated with expected fitness, this demonstrates that begging is a costly behavior, an assumption routinely made in modelsof begging behavior.
Miguel A. Rodryguez-Girones, Jesus M. Zuniga and Tomas Redondo, Behavioral Ecology Vol. 12 No. 3: 269-274