Harris's hawks are medium-large birds of prey that are found in the Americas. They have dark brown plumage with chestnut shoulders, wing linings, and thighs, white on the base and tip of the tail, long, yellow legs and a yellow cere. These beautiful birds are notable for their behavior of hunting cooperatively in packs consisting of tolerant groups, while other raptors often hunt alone. Harris hawks' social nature has been attributed to their intelligence, which makes them easy to train and have made them a popular bird for use in falconry.
Harris's hawks breed from the southwestern United States south to Chile, central Argentina, and Brazil. These birds are permanent residents and do not migrate. They live in sparse woodland, semi-desert, savannah, shrubland, and in some parts of their range in marshes (with some trees), including mangrove swamps.
Harris's hawks are social birds and live in groups. These groups have a dominance hierarchy, wherein the mature female is the dominant bird, followed by the adult male and then the young of previous years. Not only do birds cooperate in hunting, but they also assist in the nesting process. Harris's hawks hunt by day in cooperative groups of 2 to 6. This is believed to be an adaptation to the lack of prey in the desert climate in which they live. These birds use several hunting techniques; in one technique a small group flies ahead and scouts, then another group member flies ahead and scouts and this continues until the prey is bagged and shared. In another hunting technique, all the group members spread around the prey and one bird flushes it out. When Harris's hawks need to communicate with each other, they use very low, harsh sounds. When birds are alarmed, they make a prolonged and harsh “irrr”.
Harris's hawks form long-lasting monogamous pairs. It is suggested that females may also exhibit a polyandrous mating system (one female mates with several males); however, this is still debating, as it may be confused with "backstanding" (one bird standing on another's back). Harris' hawks breed throughout the year and may produce 2-3 clutches per year. These birds construct their nests in trees at 5 m of height and line them with soft materials, mosses, grasses, and roots. The female lays 2 to 4 eggs and does most of the incubation. The eggs hatch in 31 to 36 days. The chicks are altricial; they hatch helpless and with closed eyes. They begin to explore outside the nest at 38 days, and fledge, or start to fly, at 45 to 50 days. The young may stay with their parents for up to three years, helping to raise later broods.
The wild Harris's hawk population is declining due to habitat loss; however, under some circumstances, they have been known to move into developed areas. These birds also suffer from human disturbances and electrocution, because they tend to perch on electrical transformers, and are often electrocuted.
According to the What Bird resource, the total Harris’s hawk population size is around 390,000 individuals. According to the All About Birds resource, the total breeding population size of the species is 920,000 breeding birds. Overall, currently, Harris’s hawks are classified as Least Concern (LC) on the IUCN Red List, but their numbers today are decreasing.
Harris' hawks are important predators in the ecosystem they live in. Due to their diet habits, these birds control populations of many small mammals, lizards, and birds.