Song types and their structural features are associated with specific contexts in the banded wren

We studied the use of song types and their acoustic features in different social contexts in the banded wren, Thryothorus pleurostictus, a resident tropical songbird in which males possess about 20 distinctive song types varying in duration, bandwidth, note composition and trill structure. We recorded six focal males intensively for 4 days each while we observed context information such as during versus after dawn chorus, presence of the female, countersinging versus solo singing, location at the edge versus centre of the territory, and proximity to the nest. All males used at least some song types differentially during each of these pairs of alternative contexts. Males also preferentially used the song types they shared with a given neighbour when interacting with that bird. Songs delivered during dawn chorus were significantly longer, wider in bandwidth, often compound (double songs), and more likely to contain a rattle or buzz and an up-sweeping trill, compared to songs delivered after dawn chorus. Similar features were also more commonly observed when birds were engaged in intense male-male interactions and boundary disputes after dawn chorus, especially when countersinging at the edge of the territory. In the presence of the female mate, males preferentially delivered a few particular song types that had narrower whole-song and trill bandwidths and lacked rattles and buzzes. Moreover, song-type diversity and fraction of compound songs were higher when the female was present than when she was absent. Thus, in addition to using type matching and variations in song-type switching and diversity to signal different levels of aggressive intention, male banded wrens also select song types based on their acoustic structure in different social contexts.