Machos de uma ave tropical canora ajustam o seu comportamento, mas não o seu canto, em resposta à intrusão de seu território.

Abstract

Animal communication is influenced by selective pressures and is associated with the transmission of information through signals, including acoustic ones. In birds, vocal communication can resolve conflicts, and complexity is a key feature for this resolution. Complex calls indicate male individual quality, therefore, males of greater vocal complexity can cause more aggressive reactions in their rivals, which can lead to a vocal adjustment of residents to combat the intrusion of their territories. To test whether there was vocal or behavioral adjustment by the resident males of Sporophila lineola, a tropical songbird with different dialects that usually vocalize actively in its breeding territory, playbacks of different vocal complexities were used, which simulated different rivals. We expected that males would respond more intensely and adjust features of their own calls to more vocally complex rivals compared to less complex ones. The playbacks were assembled based on the individuals who presented the highest and lowest levels of vocal complexity, obtained through principal component analysis. The 15 individuals received two tests that simulated a territorial intrusion, each one of a different type of complexity. No evidence was found of any type of vocal adjustment to the type of treatment, only changes in behavior. Males responded with more flights under the loudspeaker to less complex playback, especially during the egg laying period. Indicating that, residents can distinguish between different levels of complexity or identify the fighting ability of their rivals, but prefer to enter into direct conflicts with their opponents.