Affiliation between the Sexes in Common Grackles

II: Spatial and Vocal Coordination


Department of Zoology, University of North Carolina, Chapel Hill, N.C. 27514, U.S.A.


This study of the frequencies of activities performed by four breeding pairs of Common Grackles Quiscalus quiscula examined the behavioral regulation of partners' spatial association and vocal interactions and the possible effects of these interactions on the seasonal course and persistence of their affiliation. Spatial association of partners remained high until incubation began and then declined progressively. The ♀s' vocalizations when leaving the colony increased the chances that her mate would follow and thus promoted the pair's association. Song-answering, a form of antiphonal singing, was frequent only before the start of intensive nest-building and copulation. Measures of spatial association and frequencies of antiphonal singing were lower in pairs in which the ♀ chose her nest site early in the season, an indication that the behavior of younger and older pairs might differ. Differences in partners' interactions after choosing a nest site had no clear associations with differences in the seasonal development of their reproductive states or the persistence of their bond through incubation.