Topic summary
Passerine birds
Extracted from the Wikipedia article Passerine.
Anatomy
The foot of a passerine has three toes directed forward and one toe directed backward, called anisodactyl arrangement. The hind toe (hallux) is long and joins the leg at approximately the same level as the front toes. This arrangement enables passerine birds to easily perch upright on branches. The toes have no webbing or joining, but in some cotingas, the second and third toes are united at their basal third.