| Description | relatively small heavy-set raptor; generally blackish or sooty brown with shoulders, thighs, and underwing coverts a chestnut color; upper and undertail coverts, as well as a one-inch band at the tip of the tail are white; eyes are dark brown; eyelids, cere, and legs are yellow; immature birds vaguely streaked with white on breast and abdomen and thighs are barred with white; their upper parts are more or less edged with a rufous color, and outer tail feathers are barred |
| Sex | both sexes identical in coloration and markings; males smaller than females |
| Age | 10-15 years |
| Length | 17.5-29" |
| Wingspan | 3.5-4' |
| Weight | 1-2 lbs. |
| Habitat | sparse woodlands or semi-desert regions |
| Status | endangered in New Mexico, Arizona and Southern California due to human encroachment and habitat destruction |
| Range | lowland areas from the southwestern border of the U.S., south to southern Chile, central Argentina, and Paraguay; found east into Venezuela and the interior of Brazil, and south to Santa Catharina |
| Behavior | 2-4 white eggs, sparsely spotted with brown or lavender, are laid in a nest, usually less than 30 feet above the ground; incubation is about 28 days; young leave the nest at about 3-1/2 weeks of age; will stay close to the nest for another 3-4 months |
| Diet | small mammals, such as rats and rabbits, as well as birds, reptiles and even insects |
| Vocalization | generally silent, but will utter a long harsh scream when the nest is approached |
| Other Information | - Very family oriented, often hunting in groups; young from the previous year help the parents raise the next clutch - Known for a behavior called "stacking", one bird will perch on the top of a cactus, and as other family members approach, they will ball up their feet and land on the shoulders of the perched bird; as many as 4 birds will stand on each other's backs |