Function Of Songs In The Orange-Billed Sparrow Passerine: Evidence For Sex Convergence

Birdsong is a model system for animal communication studies. Recent studies about passerine vocalization have mainly concentrated on temperate regions where sex roles are distinct and males dominate the territory.  In temperate areas the males are the signaler and females are solely receivers. However in the tropic regions, sex roles may be reversed between the two sexes. Passerine bird species provide a great opportunity to study selective pressures and mechanisms specific to females but also to test the robustness of current theories in an empirically novel manner (Illes and Yunes-Jimenez 2008). In this study we investigated functions of female’s song in Neotropical Orange-billed sparrow (OBSP)-Arremon aurantiirostris. We found OBSP at different territories in OTS Las Cruces Biological Station and Wilson Botanical Garden and recorded their songs or responses. During our experiments we examined the role of both male and female OBSP in their territories by conducting a simulated territorial intrusion or playback by a female, male or duet pair. I studied the difference between the female and the male response before playback and after playback using three different types of stimuli (male, female and duet).  The preliminary results showed that the males sing more than female does in response to all three playback types. However they both appear to sing for the same function - territorial defense. This research is unique and very interesting to understand how communication between birds is very important in relation to their territories and their mates.