The begging behavior of nestling Eastern Screech-Owls

The behavior of adults and nestlings at nine Eastern Screech-owl (Otus asio) nests in central Kentucky was monitored by videotaping the owls in specially-constructed nest boxes. Adult screech-owls delivered 1281 prey items during 164 h of taping. Nestlings fed first by adults started to beg significantly earlier, extended their beaks higher and closer to the adult, and called at higher rates and with greater volume than did siblings that were not fed first. In addition, nestlings fed first started begging earlier, stretched their beaks higher, positioned their beaks closer to the adult, and vocalized at a higher rate than when they were not fed first. In addition, after being returned to the nest, nestling screech-owls temporarily deprived of food begged with greater intensity and were fed more often than siblings. Such results provide further evidence for the positive relationship between hunger, begging intensity, and the chances of being fed. Our results also indicate, however, that nestling mass may be important in determining which nestlings will be fed when differences in the mass of siblings reach a certain level. We observed no siblicide or other aggression between siblings. Contributing to this absence of aggression may have been the large boxes used for videotaping and an abundant food supply. It is also possible, however, that aggression and siblicide occur infrequently in broods of screech-owls.