Common chiffchaff Common chiffchaff The common chiffchaff ("Phylloscopus collybita"), or simply the chiffchaff, is a common and widespread leaf warbler which breeds in open woodlands throughout northern and temperate Europe and Asia. It is a migratory passerine which winters in southern and western Europe, southern Asia and north Africa. Greenish-brown above and off-white below, it is named onomatopoeically for its simple "chiff-chaff" song. It has a number of subspecies, some of which are now treated as full species. The female builds a domed nest on or near the ground, and assumes most of the responsibility for brooding and feeding the chicks, whilst
Genomic evolution of birds possibility of genomic expansion in mammals and reptiles. Also, there is no such genomic loss in any vertebrate group as great as that of birds. Its possible that the early chromosomic fragmentation event that lead to the appearance of microchromosomes in birds significantly contributed to this gene loss. These fragmentation events must have taken place in a common ancestor of most birds, since approximately every two out of three species studied have at least 30 pairs of microchromosomes, 2n = 80 being the size of the average karyotype of birds (with the only exception the family Falconidae, which are 2n