Relative Importance of Male Song on Female Mate Selection in the Zebra Finch (Taeniopygia Guttata)

In the zebra finch (Taeniopygia guttata), song and its social context play an important role in female mate selection. The song of the zebra finch is unique in that it can only be produced by males, which makes the species ideal for analyzing the components of male song that influence female song preference and mate selection. There are three consistent features of zebra finch song that affect female mate preference: 1) the amount of time a male sings, 2) the size and complexity of his song repertoire, and 3) the structural conformation to species or population norms (reviewed in Nowicki et al. 2002). During courtship, male zebra finches often express ‘static-visual’ and ‘dynamic-visual’ elements in sync with song (Morris 1954), which would suggest that such behaviors also play a role in influencing female mate preference. However, with courtship comes the competition between males for the attention of potential mates. These agonistic interactions between males act settle disputes over access to mates, and as such, are also likely to influence female mate selection. As follows, we predict that, at the initial onset of courtship, there would be a higher prevalence of male-to-female courting interactions and singing behavior in comparison to male-to-male agonistic tendencies if female mate selection is fundamentally determined by song preference. However if female mate selection is more complicated than simple song preference, we would expect to initially observe a higher number of agonistic interactions between males as they compete for dominance. This hypothesis was tested by recording and analyzing the behavioral interactions between male and female zebra finches in the context of song complexity. We found that different males scored higher for song complexity than those for expression of courtship behaviors, which indicates that different elements of male courtship display likely influence female mate preference. Our data comparing male-to-male interactions and male-to-female interactions within the first 30 minutes after introduction was statistically insignificant, suggesting that female mate selection is more complicated than simple song preference. This preliminary research can be used as a basis for future studies using quantitative movement tracking analysis, which would further strengthen these initial observations. By increasing our understanding of the influence the male song has on female mate selection, we can better expound upon the nature and function of the favored traits that male songbirds possess and the benefits that females and their progeny might gain from choosing a male with these particular attributes