Sex-specific effects of incubation temperature treatment on singing behaviour

How incubation temperature affects sexual signals, such as birdsong structure and singing behaviour, has rarely been explored, especially in wild free-living animals. To address this knowledge gap, we exposed wild superb fairy-wren eggs to three incubation temperature treatments 1. Naturally variable (natural nests) 2. Cooler (constant 37 degrees Celsius) and 3. Hotter (37–39 degrees Celsius). We then banded hatched chicks and recorded their song and singing behaviour as fledglings. In doing so, we sought to address two core questions (1) Does incubation treatment affect singing behaviour (singing onset, song rate, and song complexity) in fledglings? and (2) Were there sex specific differences in how incubation treatment affected singing behaviour? Contrary to our predictions, we found no evidence that incubation temperature treatment affected the complexity of song or the age at which singing began. However, we did find sex specific effects of differing incubation temperature treatment on song rate in fledglings.