Maximum frequency of songs reflects body size among male dusky warblers Phylloscopus fuscatus (Passeriformes: Phylloscopidae)

Abstract

Song plays a vital role in communication in songbirds, primarily for territorial defense and mate attraction. Larger animals, having larger vocal organs, produce low sound frequencies more efficiently. Accordingly, the frequency of vocalizations is often negatively correlated with body size across species, and also among individuals of many species, including several nonsongbirds. However, little is known about whether song frequency reveals information about body size among males. We tested for the predicted positive relationship between body size and song traits in male dusky warblers (Phylloscopus fuscatus). In many animal species, some vocalizations are difficult to produce and can therefore indicate quality of signalers. Male dusky warblers produce songs with trilled sequences that are limited in their timing and frequency structure by physiological constraints on vocal performance. We investigated whether there was a relationship between body size and trilled vocalizations in the dusky warbler. We recorded songs of free-living male dusky warblers at dawn, and captured birds with mist nets for morphometric measurements (tarsus length, as an indicator of body size). We conducted correlation analyses between tarsus length and a composite measure of songs. In dusky warblers, body size was not significantly related to the average frequency of their overall songs, low frequency, bandwidth frequency, average note number of songs, or average song duration. In contrast, the maximum frequency of song was found to correlate positively with tarsus length. For trilled vocalizations, we found most trill traits were not significantly related to body size, and only the maximum frequency of trills was positively related to body size. Additionally, the maximal value of frequency bandwidth decreased with increasing trill rates. Overall, these results suggest that in male dusky warblers, the maximum frequency of the entire song is a reliable indicator of body size.

Bioacoustic monitoring of animal vocal behavior for conservation

“…In male songbirds, mate attraction is a chief function of singing, as is territory defense (Catchpole & Slater, 2008;Marler & Slabbekoorn, 2004;Nowicki & Searcy, 2005). Moreover, since singing is physically challenging, higher quality males, or those occupying higher quality territories, should sing songs that are closer to a physiological performance limit (Liu et al, 2017;Nowicki & Searcy, 2005). Song complexity, singing rate, singing duration and repertoire size have been shown to influence females' behaviors (Catchpole & Slater, 2008).…”

“…Song complexity, singing rate, singing duration and repertoire size have been shown to influence females' behaviors (Catchpole & Slater, 2008). Moreover, since singing is physically challenging, higher quality males, or those occupying higher quality territories, should sing songs that are closer to a physiological performance limit (Liu et al, 2017;Nowicki & Searcy, 2005). This can lead to a reproductive advantage.…”

Is male condition corrected with song features in Dusky Warblers (Phylloscopus fuscatus)

“…Recently, this relationship has been demonstrated within a single species as well, including various insects, birds, and mammals (Davies and Halliday 1978;Cardoso 2012;Linhart et al 2012;Linhart and Fuchs 2015). However, this relationship is inconsistent in some species (Galeotti et al 1997;Patel et al 2010;Potvin 2013;Linhart and Fuchs 2015;Miyashita et al 2016;Liu et al 2017). This raises questions about the underlying mechanisms.…”

“…Male Dusky Warblers sing before and after pairing to ensure within-pair paternity and acquisition of extra-pair copulations (Forstmeier and Balsby 2002). Peak song frequency is positively related to tarsus length, suggesting that peak frequency is a reliable indicator of tarsus length (Liu et al 2017). Dusky Warblers defend their territory throughout the breeding season, while other passerines give up their territory during the post-nuptial moulting period (Forstmeier 2002).…”

Egg recognition in Cinereous Tits (Parus cinereus): eggshell spots matter

“…The study was carried out in Saihanba National Forest Park, Weichang, Hebei (42°02ʹ-42°36ʹN, 116°51ʹ-117°39ʹE). It is the main natural secondary forest and plantation forest area in Hebei, with an altitude of 1500 m. It has a cold temperate continental monsoon climate (Liu et al 2017). Zuojia Nature Reserve was in Jilin, northeastern China (44°1ʹ-45°0ʹN, 126°0ʹ-126°8ʹE).…”