Song playback initiates nest building during clutch overlap in mockingbirds, Mimus polyglottos. Animal Behavior, 1990, 39, 943-953. (with L. Hyatt and L. Gregorcyk) (original) (raw)

Mockingbirds commonly show clutch overlap, initiating work on a subsequent brood while older young remain dependent on parental care. Several days before the male begins to build a new nest, he resumes singing. The result is a cyclic pattern of singing in which song ceases during the nestling period and recurs each time the male builds a nest. To determine if song can stimulate renesting in the presence of dependent young, and thereby regulate the amount of clutch overlap, mated males were played song earlier in the breeding cycle than they would normally begin to sing. Experimental pairs were played 140 min of mockingbird song per day in their territories beginning at nestling day 6 and continuing through the onset of renesting. They began nest building sooner and built more before the older young fledged than either males that heard no song or two that heard brown thrasher, Toxastoma rufum, song. In several pairs hearing mockingbird song, nest building continued after the stimulus song ceased, and the female laid in the nest begun in response to song. The amount of nest building was positively correlated with the male's initial aggressive reaction to the speaker playing song, but unrelated to the amount of his own song production. These data constitute the first demonstration in the field of the role of passerine song in re-initiating breeding in established pairs.