Attendants at Tree Swallow Nests. III. Parental Responses to Live and Stuffed-Model Attendants

Abstract

Attendants are common at Tree Swallow (Tachycineta bicolor) nests during the nestling period. Parent-attendant interactions were studied at a Tree Swallow nest box trail in New York. Attendants did not cooperate with parents (Lombardo 1986a) and were hypothesized to be individuals in search of potential future nest sites (Lombardo 1987). Therefore, they posed several potential threats to parental reproductive success. Even though parents commonly encountered attendants at their nests, parent-attendant interactions were usually nonhostile. Parents were very unresponsive to model-attendants during the nestling period. Parents infrequently chased live attendants or attacked model-attendants presumably because the potential threats posed by attendants were rarely realized. Attendants were most active late in the breeding season when it was too late for attendants capable of breeding to breed successfully. Hatching year attendants had little to gain by behaving aggressively towards parents. This mutual restraint in conflict could be maintained by reciprocity (Lombardo 1985).