White-tailed Hawk

En bref

  • Scientific Name: Geranoaetus albicaudatus
  • Spanish Name: Aguilucho coliblanco
  • Famille : Accipitridae
  • Known Nicknames: White-tailed Buzzard
  • Average Length: 46–58 cm / 18–23 in
  • Average Weight: 800–1100 g / 1.8–2.4 lb
  • Wingspan: 120–150 cm / 47–59 in
  • Key Feature: White tail with a distinct black subterminal band
  • Régime alimentaire principal : Carnivore
  • Range: Southern Texas, Central America, and South America to central Argentina
  • Habitat: Open grasslands, savannas, and arid scrublands
  • Structure sociale : Solitaires ou en couples
  • Nesting/Breeding: Stick nest in a tree or cactus
  • Statut de conservation : Préoccupation mineure (LC)
  • Évolution démographique : Stable

The White-tailed Hawk (*Geranoaetus albicaudatus*) is a striking raptor of open grasslands and savannas from the southern United States to Argentina, instantly recognizable by its bold, contrasting plumage. Adults boast a dark gray hood and back, a rich rufous patch on the shoulders, and a pristine white underside and tail with a distinctive, broad black subterminal band near the tip. Its most unique characteristic is its highly variable juvenile plumage, which can range from nearly all dark to heavily streaked, making identification a challenge even for experts. A special feature is its hunting style: it often hovers low over the ground like a giant kestrel before dropping onto prey, and it is notably gregarious, frequently seen in pairs or small family groups that perform dramatic, sky-dancing courtship displays.

Faits amusants

White-tailed hawks are notorious for their "broken-wing" act, where they feign injury on the ground to lure predators—like coyotes or humans—away from their nest, a behavior more common in plovers than raptors. They also have a bizarre dietary quirk: they frequently follow wildfires, snatching scorched rodents and insects fleeing the flames, and will even eat venomous snakes, including rattlesnakes, by stomping them to death with their powerful talons. Another unique adaptation is their soaring style—they often hold their wings in a distinctive shallow "V" (dihedral) while circling, making them look like oversized, lazy vultures even though they are true buteos.

Habitats et répartition

The White-tailed Hawk inhabits open and semi-open landscapes, primarily savannas, grasslands, scrublands, and agricultural fields, often near water sources like marshes or rivers. It avoids dense forests, favoring areas with scattered trees or low perches for hunting. Its geographical range extends from southern Texas and coastal Mexico through Central America, and across much of South America east of the Andes, including Venezuela, Brazil, Argentina, and Uruguay. It is resident year-round in these regions, with some seasonal movements in response to food availability.

Comportements & Reproduction

White-tailed Hawks are generally monogamous, with pairs often remaining together across multiple breeding seasons. Their courtship involves aerial displays, including steep dives and mutual soaring, to reinforce the pair bond. Nesting typically occurs in the dry season, with both sexes collaborating to build a large stick nest placed in a tree, cactus, or on a human-made structure like a utility pole. The female lays one to two eggs, and while she primarily incubates them, the male provides food during this period. A unique strategy is the frequent asynchronous hatching, where the second chick hatches a few days later than the first. This often leads to siblicide, where the older, stronger chick may kill or outcompete the younger one, ensuring that at least one offspring survives in times of food scarcity, though both can fledge in years with abundant prey. The young fledge after about two months but remain dependent on the parents for several more weeks. Socially, these hawks are typically solitary or seen in pairs, though non-breeding juveniles may form loose, temporary groups in areas with high prey density.

Alimentation

The White-tailed Hawk is an opportunistic carnivore with a highly varied diet that primarily consists of small to medium-sized mammals, reptiles, birds, and large insects. It frequently hunts from a perch or while soaring, using its keen vision to spot prey such as rabbits, ground squirrels, rats, snakes, lizards, and frogs. Interestingly, it is known to follow agricultural machinery or wildfires to capture rodents and insects flushed from cover, and it will also scavenge on roadkill or carrion. A notable dietary specialization is its fondness for venomous snakes like rattlesnakes and coral snakes, which it dispatches with swift, precise strikes, and it often consumes prey whole after removing the head of larger animals.

Couleurs

The White-tailed Hawk is a striking raptor with a pale gray head and upper breast, contrasting with a dark brown to blackish back and upperwing coverts. Its most distinctive feature is a pure white underbelly, undertail coverts, and a short white tail with a single broad black subterminal band. The wings show a unique pattern from below: white on the inner flight feathers and blackish on the outer primaries, creating a bold two-tone effect. This countershading—pale below, dark above—serves as camouflage against the sky when viewed from below and against the ground from above.