The Brown-headed Cowbird is a widespread blackbird species in Arizona, most common in open woodlands, agricultural areas, and suburban edges. Adult males are glossy black with a distinctive chocolate-brown head, while females are smaller and gray-brown with streaking. Unlike most birds, cowbirds do not build their own nests; instead, they are obligate brood parasites, laying eggs in the nests of over 200 host species in North America. In Arizona, hosts include small songbirds such as warblers, vireos, and sparrows, whose own young often fail to survive when outcompeted by the larger cowbird chick. This parasitic strategy has had particular conservation impact on threatened species like the Southwestern Willow Flycatcher (Empidonax traillii extimus), whose populations are under pressure from cowbird parasitism. While considered native to the Great Plains, Brown-headed Cowbirds expanded into Arizona following deforestation, agriculture, and the introduction of livestock, which created more suitable open habitats. Today they are widespread year-round residents in the state, though their numbers fluctuate with habitat conditions.
