The vocal behavior of the Brown-throated Wren (Troglodytes brunneicollis): song structure, repertoires, sharing, syntax, and diel variation

Empirical descriptions of vocal behaviour are important for understanding avian biology. In this study, we provide the first detailed analysis of the vocal behaviour of the Brown-throated Wren (Troglodytes brunneicollis), a neotropical songbird found in oak forests in the highlands of Mexico and the southwestern United States. We quantify the fine structural characteristics of the song, and describe the size and structure of the song repertoire. Further, we describe diel variation, analyze song-sharing patterns among neighbors, and explore whether this species uses syntactical rules for creating their songs. Our analyses reveal that Brown-throated Wrens have complex songs and simple calls. They sing with eventual variety, repeating songs many times before switching to a new song type. Males combine syllables into phrases to create songs. We show that song repertoire size is not fixed; birds recombine their syllables to produce highly variable song types. Brown-throated Wrens sing with high vocal output after sunrise and song activity declines throughout the morning. Song sharing shows no variation with distance among our sampled individuals. We divide the syllables in Brown- throated Wren songs into 13 categories; birds sing some syllables more frequently than others, and some syllables are more likely to be found at the beginning, middle, or end of the song. Transitions between syllable categories deviate significantly from random chance, and most males ana- lyzed follow similar patterns of syllable transitions, revealing syntactical structure. This research, which pro- vides the first empirical study of Brown-throated Wren song, expands our knowledge of the behaviour of this poorly-studied taxon, and contributes insight into the organization and composition of song in tropical birds.