| Abstract: | Wild zebra finches sing frequently during the breeding season, but the vast majority of song is of the undirected song type that is not directed at any individual, and the function of which is obscure — it appears to be ignored by all potential recipients. It is sung close to the nest-site, has a peak in production during the egg-laying period, and diminishes thereafter. The incidence of undirected song is positively correlated with extra-pair courtship, a finding consistent with the hypothesis that it is a means of advertising availability for extra-pair matings. Typically, undirected song occurred outside the nest when the female was inside, and a positive relationship was found between the amount of singing given by the male during the 5-min interval immediately after the female entered the nest and the time she subsequently spent inside the nest. Keeping the partner inside the nest during her fertile period is an advantage to the male: it serves as a form of paternity protection against other males and it allows him opportunities to pursue his own extra-pair matings. Occupancy of the nest during laying is also a means of guarding against intraspecific brood parasitism, which was high at this colony. |
