Falco unicinctus Temminck, 1824, western Minas Gerais, Brazil. Two subspecies.
OTHER COMMON NAMES
English: Bay-winged hawk; French: Buse de Harris; German: Wьstenbussard; Spanish: Busardo Mixto.
19–22 in (48–56 cm); male: 25 oz (725 g), female: 34 oz (950 g). Sooty brown body, with rufous accents on shoulders, thighs, and underwings, and black tail.
P.u. harrisi: southwest United States to Mexico, Central America, western Colombia, Ecuador, and Peru. P.v. unicinctus: Northeastern Colombia and western Venezuela to Bolicia, Brazil, Chile, and southern Argentina.
Seasonally dry desert, Chaco and savanna, occasionally swampland. In more arid regions, near large waterbodies.
FEEDING ECOLOGY AND DIET
Hunts large prey for its size, mostly mammals, up to the size of rabbits and jackrabbits, also birds including flickers and rails. Also reptiles (snakes and lizards) and insects. Hunts larger prey co-operatively, social groups of two to six gather at dawn to work through territory to flush, ambush, and sequentially attack rabbits.
Typically monogamous, usually nesting as solitary pair. Builds a stick nest, lined with moss, grass and leaves, in a tree. Lays one to four eggs in June–July. Incubation about 34–35 days; fledging about 40 days. Some pairs renest in late summer or early autumn, even following a successful first (winter) nesting attempt. Cooperative breeding reported in United States but not elsewhere: one to five juvenile or adult helpers bring food and defend the nest of the dominant (alpha) pair. The beta birds appear to be unrelated to the breeding pair and the gamma birds are often young from the previous breeding attempt.
Not threatened. Occasionally poisoned by strychnine-baited carcasses left by sheep farmers for other predators. Reintroduced to California, where small population established.
SIGNIFICANCE TO HUMANS
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