Zone-tailed Hawk Life History

Habitat

In the southwestern U.S., including western Texas, Zone-tailed Hawks inhabit all but the highest elevations. They often hunt in desert scrub and grasslands, and they use river courses with cottonwoods and willows for both nesting and hunting. Zone-tailed Hawks also thrive in arid foothills above 3,000 feet, especially with rocky canyons and cliffs, and often forage much higher, into mixed and coniferous (usually pine) forests up to about 7,600 feet, where they prefer edges and clearings. From Mexico to Argentina, Zone-tailed Hawks inhabit a similarly wide range of elevations and habitats, from coastal plains to montane pine and pine-oak woodlands. Migrants from the northern part of the range (including the United States) probably select similar habitats on the wintering grounds.

Food

Zone-tailed Hawks eat mostly birds, mammals, reptiles, and amphibians. There are even reports of them eating fish. To hunt such a variety of prey, they have numerous strategies. Their chief tactic appears to be flying slowly and rather low over uneven terrain, rocking a bit side to side with wings held upswept (thus resembling a Turkey Vulture), then dropping suddenly onto a lizard, small mammal, or ground-dwelling bird. Less frequently they may hunt by chasing and capturing flying birds. Zone-tailed Hawks use trees and other landscape features as screens when approaching prey, to conceal themselves until just before striking. Less common strategies include hunting from a tree perch, and taking birds perched in trees. In boulder-strewn habitats they prey heavily on large lizards, especially common collared lizards and crevice spiny lizards. Such habitats also have prey such as ground squirrels, antelope squirrels, rock squirrels, chipmunks, and rabbits. Scaled, Montezuma, California, and Gambel’s Quail are common prey items, as are woodpeckers (Acorn Woodpecker, Northern Flicker), nightjars (Common Nighthawk, Common Poorwill), jays (Woodhouse’s Scrub-Jay, Steller’s Jay), thrushes (American Robin, Western Bluebird), and other passerines including Cassin’s Kingbird, Red Crossbill, Western Meadowlark, and Rufous-crowned Sparrow. Diet in tropical regions is even more varied.

Nesting

Nest Placement

Nest are set high in the crotch of a tall tree, usually oak or pine.

Nest Description

Both male and female construct a large stick nest, using mostly oak and pine, then line the bowl with bark, leaves, pine needles, and moss. Nest dimensions vary; one example measured was 23.6 inches across and 19.7 inches tall, with interior cup 8.3 inches across and 3.9 inches deep.

Nesting Facts

Behavior

Zone-tailed Hawks commence courtship displays in early spring, just after returning from wintering areas. Males sometimes display alone, but often the courting pair ascends together, to 1,000 feet in the air or more, and begins to circle and call together, extending the legs as they circle. At altitude, they begin a series of figure-8 loops around each other, diving swiftly, then pulling up, complementing each other’s configurations and even crossing flight paths. Some pairs also perform barrel rolls, in which they loop forward as well as sideways, and some pairs also lock talons and tumble toward earth, whirling slowly like a giant maple seed. Their aerial displays may go on for an hour. In some cases, the pair mates just afterward, but in others, the displays may be responses to the presence of another male in the territory. The displays occur throughout the nesting season and so are not simply for initial courtship. Active nests can be as close as 1,000 feet from each other. Both adults share incubation duties and feed the young.

Conservation

Zone-tailed Hawk populations may be increasing in the United States as the species expands its range. Partners in Flight estimates a global breeding population of 2 million, but the great majority of these are in Mexico through South America—the U.S. population is estimated at below 2,000 breeding individuals. Partners in Flight rates the species a 10 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Development and other landscape modifications have eliminated much historical nesting and foraging habitat, and habitat loss continues to be the chief conservation threat to this species. Although Zone-tailed Hawks and other raptors are less often shot and persecuted as “pests” than in the past, they are still vulnerable to disturbance at nest sites.

Credits

Crossley, R., J. Liguori, and B. Sullivan. (2013). The Crossley ID Guide: Raptors. Princeton University Press, New Jersery, USA.

Johnson, R. Roy, Richard L. Glinski and Sumner W. Matteson. (2000). Zone-tailed Hawk (Buteo albonotatus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A., and A. S. Love (2017). Longevity records of North American birds. Version 2017.1. Patuxent Wildlife Research Center, Bird Banding Laboratory, Laurel, MD, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Rosenberg, K. V., J. A. Kennedy, R. Dettmers, R. P. Ford, D. Reynolds, J. D. Alexander, C. J. Beardmore, P. J. Blancher, R. E. Bogart, G. S. Butcher, A. F. Camfield, A. Couturier, D. W. Demarest, W. E. Easton, J. J. Giocomo, R. H. Keller, A. E. Mini, A. O. Panjabi, D. N. Pashley, T. D. Rich, J. M. Ruth, H. Stabins, J. Stanton, and T. Will (2016). Partners in Flight Landbird Conservation Plan: 2016 Revision for Canada and Continental United States. Partners in Flight Science Committee.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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