Many animals communicate using more than one signal, and several hypotheses exist to explain the evolution of multiple signals. However, these hypotheses typically assume static selection pressures and previous work has not addressed how spatial and temporal environmental variation can shape variation in signaling systems. In particular, environmental variability, such as ambient lighting or noise, may affect efficacy (e.g. detectability/perception by receivers) of signals. To examine how signal expression varies intraspecifically as a function of habitat characteristics, we evaluated relationships between spatial environmental variation and song and plumage color expression in a tropical songbird, the red-throated ant-tanager (Habia fuscicauda) in Panama. We recorded male ant-tanager song, plucked feathers to measure coloration, and recorded the acoustic and light environments from each male’s territory. In addition, we took several morphometric measurements from each male to assess the potential information content of song and plumage color. We found that males with redder and more saturated crowns occurred on darker territories, and males that sang shorter and lower frequency songs occurred on noisier territories. We also found that more colorful males tended to sing longer and lower frequency songs. Finally we found that song and color correlated similarly with male morphology (e.g. tarsus length, body mass). Altogether these results indicate that spatial variation in the environment is related to male coloration and song, and that males might be optimizing color and song expression for their particular territorial environment.

RTAT_dataExcel sheet containing the song, color, and morphological data from male red-throated ant-tanagers (RTAT). The excel sheet also contains the territory ids, song, color, and morphology principal components, and the playback ID used to elicit male songs.