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Last updated on April 18, 2014 at 15:51 EDT

Laughing Falcon, Herpetotheres cachinnans

The Laughing Falcon (Herpetotheres cachinnans), also known as the Snake Hawk (erroneously, since it’s not a hawk), is a medium-sized bird of prey belonging to the falcon family Falconidae, the only member of the genus Herpetotheres. This Neotropical species is an expert snake-eater. Its common and scientific names are both in reference to its distinctive voice.

The English name comes from its loud voice, as does the specific name cachinnans, which is Latin for “laughing aloud” or “laughing immoderately”.

Its relationships with other members of the Falconidae are not clear. Customarily, it has been placed in the subfamily Polyborinae with the forest falcons and caracaras, but the American Ornithologists’ Union’s North American Check-list Committee now places it in the same subfamily as the true falcons, while the South American Check-list Committee places it with the forest falcons but not the caracaras, and it has also been considered a subfamily of its own.

It is 18 to 22 inches long and has a wingspan of 31 to 37 inches. As usual among birds of prey, the female is bigger, weighing 1.3 to 1.8 pounds compared to the male, weighing .90 to 1.5 pounds.

Adult birds have a pale beige head, changeable between a more brownish color and an almost white hue according to feather wear and individual variation. The broad black face mask extends across the neck as a narrow collar, bordered with white. On the crown, the feather shafts are dark, creating a somewhat streaked effect. The back and upper wings are a blackish brown color. The upper tail coverts are whitish beige again, and the rectrices are barred black and whitish, ending in white. The underside is uniformly pale beige; there may be a bit of dark speckling on the thighs, though. The underside of the wing is pale reddish-brown to beige, sometimes with some dark spotting on the underwing covert. The tips of the primary remiges are barred with pale grey below; their bases are quite rufous colored. The iris is dark brown, the feet are pale yellow, and the bill is black with a pale yellow cere.

The immature birds do not differ much from the adults; they have lighter margins to the back feathers, creating a scalloped effect. The light parts of the plumage are almost white, paler than in the adults; the unfeathered parts are also paler. The nestlings are covered in peculiarly dense down, reminiscent of a ducklings; they are normally brownish beige, darker above, and already show the blackish facial marks of the adults.

With its big white or pale beige head having a dark brown mask from the eyes around to the nape of the neck, it is unmistakable. In flight, it shows a rufous patch near each wingtip and a shape more like an Accipiter hawk than most of its falcon relatives, with short rounded wings and long tail.

The namesake call is a long series of separate, rather human-like cries, each one frequently rising sharply in pitch in the middle and sometimes falling sharply at the very end, changing from a “joyful” to a “sad” sound, and rendered as ha-ha-ha har-her-her or hawww harrr herrrer. The series may be introduced by faster Hashanah calls suggesting maniacal laughter, especially when the bird is startled. Sometimes two birds call together at different pitches and tempos, creating a striking and offbeat effect.

It has another call, usually given at dusk. This two-note call is preceded by a series of gwa notes given every half second or so. They become more emphatic and after some time change to a sequence of the gwa co call proper, with the first syllable a bit higher in pitch than the second one, but not differing in volume or emphasis. The gwa co call may be repeated fifty times or more. Sometimes, the initial calls are a oo oo-oo cow-cow-cow, sometimes a descending gwaaaa. On occasion, the two-syllable call isn’t given, and instead the simple gwa is repeated as often as the full call.

It can be found from both coastal slopes of Mexico through Central and South America south to Amazonian Peru and Bolivia, practically all of Brazil, and northern Argentina and Paraguay, at altitudes up to 4,900 ft, though it’s often absent from mountainous regions. It occupies varied habitats, usually including at least scattered trees; it prefers humid regions to arid ones and tends to keep away from closed forest. It’s usually not migratory, though in some areas it might make seasonal movements.

The flight is slow, with quick and shallow wing beats interspersed with glides; the bird rarely, if ever, soars. When it lands, it will jerk the tail forcefully like a wagtail. A Laughing Falcon frequently and often conspicuously remains on a perch four hours, sitting upright and observing the ground alertly, sometimes flicking its tail or nodding, or moving around a bit on its perch with slow and cautious little steps. It’s usually peaceful and unlike other falcons, it will not harm smaller birds.

It catches mainly snakes, including venomous ones, for example, coral snakes, and also lizards, and, to a lesser extent, small rodents, bats, and centipedes. It pounces on its prey from flight, often with an audible thud, and then biting it just behind the head, sometimes removing the head in the process. It carries its food to a perch to eat. It may carry small snakes in its bill and swallow them tail-first; big snakes may be carried with the head forward in its claws, and then torn to pieces.

The Laughing Falcon breeds in rock crevices, tree cavities, or occasionally an abandoned nest of a Buteo hawk or caracara; in general, however, it doesn’t even gather nesting material in significant amounts. It lays one or two eggs according to some sources, but according to others, always just one. The eggs have heavy dark brown markings on a brown, whitish, or pale beige background. The young are thought to leave the nest eight weeks after they hatch. The breeding season has been given as April and May, though it may well vary across the large range of this species.

Image Caption: Laughing Falcon, Herpetotheres cachinnans. Credit: Ni to il/Wikipedia (CC BY-SA 3.0)

Laughing Falcon Herpetotheres cachinnans