 Pasirine. The pasirine is any bird of the order Pasiriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, pasirines are distinguished from other orders of birds by the arrangement of their toes three pointing forward and one back which facilitates perching. With more than 110 families and some 6409 identified species, pasiriformes is the largest order of birds and among the most diverse orders of tristral vertebrates. The pasirines contain several groups of brood parasites such as the vigils, cuckoo finches, and the cowbirds. Most pasirines are omnivorous, while the shrikes are carnivorous. The terms pasirine and pasiriformes are derived from Pasirdomesticus, the scientific name of the eponymous species the house sparrow and ultimately from the Latin Pasir, which refers to sparrows and similar small birds.