One of only six passerine species endemic to the grasslands of North America, the Lark Bunting is also one of the most abundant and the least philopatric species of the Great Plains. It is one of the few sparrows in which the male molts from a cryptic Basic plumage to a completely different, boldly patterned Alternate plumage.
Lark Buntings wintering in Texas, Arizona, and the high plateau of northern Mexico wander in flocks of up to thousands that stay on the move until they find a good winter food supply. Areas of abundant natural food occur only in places receiving late summer rains, relegating this bunting to a nomadic lifestyle. During March and April, males begin to molt into their unique Alternate plumage and begin to make their slow diurnal migration northward to the high plains of central North America, where they breed.
Males arrive a few days before females; each male establishes a territory in what appears to be a colony, and begins its aerial displays. Unusual among birds, this species has developed two different Flight Songs. While its preference is natural grasslands, it has adapted well to human-altered habitats. Its ground nest is usually adjacent to a plant, one large enough to provide shade, a key factor in determining territory quality.
The mating system of this species is still not fully understood. Monogamy appears to be the norm, with polygyny observed in areas of high density; helpers at the nest have been recorded in areas of low density with high male to female ratios.
Since Henry Baumgarten's 1968 account in Bent's life-history series, considerable work has been done on the nesting ecology of this species (see Baldwin et al. 1969 , Creighton 1971a , Shane 1972 , Creighton and Baldwin 1974 , Wilson 1976b , and Johnson 1981a ), on its mating systems and behavior (see Taylor and Ashe 1976 , Pleszczynska 1977 , Nero 1982 ), and on its vocalizations (see Ervin 1981 ).