The Laughing Falcon (Herpetotheres cachinnans)

May 25, 2014 Features / Columnists, Interesting Creatures in Guyana

The Laughing Falcon (Herpetotheres cachinnans), also called the Snake Hawk (erroneously, since it is not a hawk), is a medium-sized bird of prey in the falcon family (Falconidae), the only member of the genus Herpetotheres. This Neotropical species is a specialist snake-eater. Its common and scientific names both refer to its distinctive voice.
Its English name comes from its loud voice, as does the specific name cachinnans, Latin for “laughing aloud” or “laughing immoderately”.
The generic name Herpetotheres refers to its preferred food. Its relationships with other members of the Falconidae are unclear. Traditionally it has been placed in the subfamily with the caracaras and forest falcons, 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.

Laughing Falcon

The namesake call is a long series of separate, rather human-like cries, each one often 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 haww harr herrer. The series may be introduced by faster hahahahahaha calls suggestive of maniacal laughter, particularly when the bird is startled. Sometimes two birds call together at different pitches and tempos, producing a striking off-beat effect.
The Laughing Falcon has another call, typically 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 higher in pitch than the second, but not differing in emphasis or volume. The gwa co call may be repeated 50 times or more. Sometimes, the initial calls are a oo oo-oo cow-cow-cow, sometimes a descending gwaaaaaaa.
On occasion, the two-syllable call is not given, and instead the simple gwa is repeated as often as the full call.
It is 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 1,500 m (4,900 feet) (rarely to 2,400 m (7,900 feet) in Colombia), though it is 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 avoid closed forest. It is generally not migratory, though in some areas it may make seasonal movements.
The flight is slow, with quick, shallow wing beats interspersed with glides; the bird rarely if ever soars. When it lands, it will jerk the tail forcefully just like a wagtail. A Laughing Falcon frequently and often conspicuously stays on a perch for hours, sitting upright and observing the ground alertly, sometimes flicking its tail or nodding, or moving around a bit on its perch with slow, cautious little steps. It is generally peaceful and unlike other falcons will not harm smaller birds.
It catches mainly snakes, including venomous ones such as coral snakes, and also lizards, and, to a lesser extent, small rodents, bats and centipedes. The Laughing Falcon 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 the food to a perch to eat. It may carry small snakes in its bill and swallow them tail-first; big snakes may be carried head-forward in its claws, as an Osprey carries a fish, and then torn to pieces.
The Laughing Falcon breeds in rock crevices, tree cavities, or occasionally in abandoned nests of a Buteo hawk or caracara; in general however it does not even gather nesting material in significant quantities. 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 or whitish or pale buff background. The young are thought to leave the nest eight weeks after hatching. The breeding season has been given as April and May, though it may well vary across the large range of this species.