Song duration (a) and syllables rate (b) in the different social contexts.

<p>Box plots are separated by sex and population. Abbreviations and colours as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097244#pone-0097244-g004" target="_blank">Figure 4</a>. Asterisks denote the cases where found differences were significant (p≤0.05 (*), p≤0.01 (**)).