Example of video data from experimental field study. Chicks are individually marked with acrylic paint. Videos were coded by an observer blind to supplementation treatment and chick size rank. Observer recorded the begging intensity of all chicks, which chick was fed, and which parent was feeding.
Parents feeding chicks with supplemental food. Nests were given supplemental food daily for the week after hatching, ending the day before broods were cross-fostered and parents were filmed feeding the experimental broods.