Common chiffchaff and generally pale legs. Bonelli's warbler ("P. bonelli)" might be confused with the common chiffchaff subspecies "tristis", but it has a plain face and green in the wings. The common chiffchaff also has rounded wings in flight, and a diagnostic tail movement consisting of a dip, then sidewards wag, that distinguishes it from other "Phylloscopus" warblers and gives rise to the name "tailwagger" in India. Perhaps the greatest challenge is distinguishing non-singing birds of the nominate subspecies from Iberian chiffchaff in the field. In Great Britain and the Netherlands, all accepted records of vagrant Iberian chiffchaffs relate to singing males.
Genomic evolution of birds or two cone opsin genes. Birds also seem to have lost the functionality of their right ovary. There are two ovary development-related genes, MMP19 and AKR1C3, that have disappeared in birds. The fact that a high number of genes related to spermatogenesis are evolving fast (which does not happen in those related to ovogenensis) suggest that males undergo a stronger selective pressure. The abundance of genomic data available nowadays has enabled research to elucidate the early evolution and divergence of bird groups, and has produced a much more detailed phylogenetic tree. Genomic research has shown that in order to make