An evidence-based overview of hybridization in tinamous

Abstract

Estimates suggest that about 16% of bird species hybridize in the wild. This number is based on two main sources: the Handbook of Avian Hybrids of the World by Eugene McCarthy and the online Serge Dumont Bird Hybrids Database. Although both sources provide supporting references for the documented hybrids, the reliability of these references has not been systematically assessed. In this paper, I introduce a scoring scheme based on three criteria that are weighted based on their reliability, namely field observations or photographs (1 point), morphological analyses (2 points), and genetic analyses (3 points). The final tally of these three criteria (ranging from 0 to 6 points) will indicate the level of confidence for a particular hybrid. I test this scoring scheme on the Neotropical bird family Tinamidae (tinamous), in which several putative hybrids have been reported. My analysis revealed one well-documented case (Crypturellus boucardi × C. cinnamomeus) and three doubtful records that require further investigation. These findings highlight the need for thoroughly scrutinizing the sources supporting avian hybrids. The scoring system clearly illustrates its usefulness and can be easily applied to other taxonomic groups to increase the reliability of documenting interspecific hybrids.