...it appears that, minimally, the montane Colombian form castaneus merits recognition as a distinct biological species based on its remarkably different song and distinct elevational distribution (Fig. 2, 4). The degree of vocal and ecological differentiation between castaneus and other populations is comparable to, or even greater than, variation existing among good (i.e. reproductively isolated) species of tinamous (Cabot 1992, Maijer 1996), a criterion often used to treat allopatric populations as different species under the BSC (reviewed by Remsen 2005). Alternatively, if one were to follow species concepts based on diagnosability (e.g. the phylogenetic species concept, Cracraft 1983), which are often used in ornithology (Sangster 2014), then it is likely that several species would need to be recognized in the brown tinamou group. In turn, vocal variation does not support the split of C. erythropus into more species than currently recognized (Remsen et al. 2014) as has been suggested by some authors (Collar 1992, Renjifo et al. 2002, BirdLife International 2008). Intriguingly, our analyses indicate that C. kerriae, which has never been considered part of this group, exhibits songs within the range of vocal variation existing in C. erythropus, suggesting these two taxa may well be conspecific and that their phenotypic distinctiveness should be recognized at the subspecies level. ...
