Seasonal change in the vocal behaviour of female red-winged blackbirds, Agelaius phoeniceus
Yasukawa, K.; Boley, R.A.; Simon, S.E.
Animal Behaviour 35: 16-23
ISSN/ISBN: 0003-3472 DOI: 10.1016/s0003-3472(87)80014-3
Seasonal change in the vocal behaviour of female red-winged blackbirds, Agelaius phoeniceus, was observed in order to test hypotheses for the function of their vocalizations. The ‘Chit’ vocalization was given at relatively consistent rates throughout the nesting cycle, but females rarely gave Chits once their young left their nests, and females who did not receive male assistance in feeding nestlings gave Chits at higher rates than did assisted females. The rate at which the intrasexually aggressive ‘Teer’ was given declined through the nesting season and primary (first-to-nest) female redwings gave Teers at lower rates than did later-nesting females. It is tentatively concluded that the Chit functions in intersexual communication and the Teer functions to delay nest initiation by late-arriving females.