Evaluating the association between vocalizations and colouration in finches (Fringillidae), a passerine group with elaborate signals

Abstract

The interaction between multiple secondary sexual characters simultaneously expressed by an organism remains poorly understood. In fact, different interpretations of the role of concurrently expressed signals predict that the correlation of their elaboration across species should be positive, negative or absent --all three possibilities have been supported by studies of different avian groups. In this context, we analysed the interaction between plumage and song elaboration in the passerine family Fringillidae (finches). We used a two-scale approach and studied this association both at the family level and in more detail within the genera Crithagra and Spinus. At both scales, we determined colour elaboration (defined by the number of plumage colour patches in each species and their contrast) and established its association with three aspects of vocal elaboration: energy investment (song length and rate of syllable production), song complexity (repertoire index) and vocal performance (vocal deviation). We found an absence of association between colour elaboration and the three evaluated aspects of song elaboration at both scales, which has been the most frequent result in other avian groups. At first glance, this result appears to be partially discordant with previous findings in finches, but considering these studies together this might not necessarily be the case. We also confirmed that finches have complex songs and a remarkable vocal performance compared to other families of passerines. Considered together, our results suggest an independent evolution of colour and the notable vocal elaboration present in finches.