Passerines are, in simple terms, perching birds. They make up the largest and most diverse order of birds in the world. The scientific name for the order is Passeriformes. You are surrounded by passerines every day. In fact, more than half of all known bird species are passerines. Their most defining characteristic is their perching feet: They have a unique foot structure with three toes pointing forward and one strong, flexible toe (the hallux) pointing backward. This arrangement, along with sp