Soft song during aggressive interactions: Seasonal changes and endocrine correlates in song sparrows

Quiet threats: soft song as an aggressive signal in birds

“…The second, why reliable?, question seems to have a more solid answer in the form of a receiver retaliation cost: although early tests of this hypothesis failed to find evidence for higher levels of aggression to soft calls compared to loud calls, later experimental tests for the most part support the predicted pattern of receiver response (Anderson et al 2012;Rek & Osiejuk 2011;Templeton et al 2012;Xia et al 2013). More studies in taxa other than songbirds are still needed to test whether aggressive soft vocalizations are also maintained by receiver retaliation costs in other species.…”

“…Another interesting finding is that both aggressive signalling and aggressive behaviours are individually consistent in song sparrows (Akçay, Campbell & Beecher 2014;Anderson et al 2012;Hyman et al 2004;Nowicki et al 2002). Furthermore, a recent study in song sparrows suggests that at least some of the variation in reliable signalling (via soft song and wing waves) reflects consistent differences between individuals: in repeated trials over several months some individuals consistently undersignalled while others consistently over-signalled relative to their aggression levels (Akçay et al 2014).…”

“…Seasonal variation in soft song production. A final finding worth considering is that use of soft song may vary seasonally in a systematic pattern (Maddison et al 2012). Seasonal variation was first revealed in a study of a song sparrow population from British Columbia, Canada, where Maddison and colleagues (2012) found that song sparrows use significantly more soft songs in response to intrusions during the non-breeding season (December) than during the breeding season (June-July).…”

Uneven Sampling and the Analysis of Vocal Performance Constraints

“…When a data set was subdivided by population, subspecies, sex, morph, or recording year, we conducted analyses only on the pooled species-level data set. For one data set (Maddison et al 2012), trills had been subdivided into slow "trills" and fast "buzzes," and each had been analyzed separately; we also analyzed these data separately because trills and buzzes are thought to involve different respiratory mechanisms and thus be subject to different performance trade-offs (Hartley and Suthers 1989;Podos 1997). Finally, there was one single-species data set and one multispecies data set where outliers were removed before analysis (Cardoso and Hu 2011; Kagawa and Soma 2013).…”

Vocal behaviour during aggressive encounters between Siberian hamsters, Phodopus sungorus

“…Exploration of seasonal variation in the production of aggressive vocalizations could therefore be an interesting direction for future research. In addition to hamsters, song sparrows, Melospiza melodia, also display year-round aggression, changing the composition and characteristics of song across breeding versus nonbreeding periods (Maddison, Anderson, Prior, Taves, & Soma, 2012;Wingfield, 1994). For hamsters, we would predict that the incidence of BBCs in general, and rattle calls in particular, increase when hamsters are placed in shortday conditions that evoke nonbreeding-like suites of behaviour and increased levels of aggression.…”