Introduction

The Zone-tailed Hawk is a Neotropical Buteo that reaches its northernmost limits in the southwestern United States. It is widely distributed, breeding as far south as central South America. Although adapted to a variety of habitats, the Zone-tailed is uncommon and patchily distributed, for reasons that are not well understood. Its habits and distribution are best known at the northern periphery of its range, where it is a migrant; south of the United States and northern Mexico, it is a poorly known permanent resident.

Occurring in diverse lowland and higher-elevation habitats, the species ranges from riparian woodland and humid forests to semiarid open country and montane highlands. One of the 2 darkest hawks in North America, the Zone-tailed lacks the light morph exhibited by many Buteo species. In the United States and many areas farther south, the Zone-tailed and similarly dark Common Black-Hawk (Buteogallus anthracinus) often occur together in the same habitat. Historically, this has lead to confusion in identification and some uncertainty about the accuracy of published sight records of the species.

The Zone-tailed Hawk engages in spectacular courtship displays, performing aerial loops, dives, and rolls, with both male and female diving from heights of about 300–500 m. A foraging generalist, this species’ diet consists largely of birds, mammals, and lizards. It is aggressive in the defense of its nesting territory, attacking animals as large as Golden Eagles (Aquila chrysaetos), Red-tailed Hawks (Buteo jamaicensis), and humans.

One of the least known birds of prey in North America, the Zone-tailed Hawk remains relatively unstudied. The work of Millsap (1981) in Arizona, Kennedy et al. (1995) in New Mexico, and Matteson and Riley (1981) in Texas are the only substantial works to date. In Arizona, this raptor is not threatened. Its range appears to be expanding (Snyder and Glinski 1988, Snyder 1998) in other parts of the southwestern United States as well. Although the fascination of early explorers (Bendire 1892, Bent 1937), it has attracted only casual modern attention.