Falconidae  

Most falconids are carnivores, though several species are scavengers and some caracaras include plant matter in their diet. As a whole, falconids eat a wide variety of prey. While some species are more specialized than others, most will opportunistically take a variety prey. Prey items include mammals (from mice to lambs), adult and nestling birds, snakes, lizards, turtles, frogs, fish, crayfish, adult and larval insects, wasp and bee nests, fruit, carrion and dung. Most falconids catch prey from soaring flight or by darting from a concealed perch, but a variety of other hunting methods are also employed. Pairs of Aplomado falcons (Falco femoralis) hunt cooperatively to flush and catch small birds. Some caracaras walk or run over the ground to scatter and catch insects. Yellow-headed caracaras (Milvago chimachima) pick ticks from the backs of cattle, among other hunting methods. Kleptoparasitism (stealing food from other birds) is a common behavior among falconids, who steal from gulls, pelicans and other raptors. Food caching is also quite common.

Foraging Behavior: stores or caches food

Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore , Eats eggs, Insectivore , Eats non-insect arthropods, Scavenger ); herbivore (Frugivore )

Falconids do not have many natural predators. However, colonial-nesting and foraging species are known to cooperatively defend against potential predators, which include eagles.

Known Predators:

• eagles (Accipitridae)

Falconids use calls to advertise ownership of a territory, to communicate between mates or group members, and in territorial or food disputes. Pairs of breeding forest-falcons sing duets before sunrise, a behavior that presumably functions to advertise their occupation of a territory, and perhaps to strengthen the pair bond. Chicks and females also use vocalizations to beg for food. The vocalizations of falconids are simple, repeated monosyllabic calls, described variously as cackles, chatters, squawks, croaks, wails and whines. Other behaviors used to communicate include flight displays, such as repeated plunging dives near the nest to advertise ownership of a territory or as a part of courtship. Plumage patterns and other physical characteristics, such as the bare skin on the face of the crested caracara (Caracara cheriway) that changes from orange to yellow in excitement, may serve as social signals of good health or prowess, or may advertise occupation of a territory.

Sight is the most important sense used for hunting. Falconids have exceptional eyesight, which they use for catching fast-moving prey. Sound is also used by some forest-dwelling species, many of which have a ruff of stiff feathers around the face that help to capture sound.

Communication Channels: visual ; acoustic

Other Communication Modes: duets

Though the breeding habits of some species (including most forest-falcons) are unknown, most falconids are believed to be monogamous, and to breed as solitary pairs. Most species are also territorial breeders, defending a hunting territory around the nest site. Resident species may defend a territory year-round. Males of migrant species typically arrive at the nest site before females. Territorial and courtship displays are performed by the male alone, and sometimes by the breeding pair, and include characteristic perched and flight displays near the nest site, accompanied by vocalizations. About ten species nest colonially at least occasionally. Even colonial species breed in individual pairs, and most pairs breed together for many years. Polygyny has been recorded infrequently in a few species. However, it is not known to be typical of any species. Two species of falconids, red-throated caracaras (Ibycter americanus) and collared falconets (Microhierax caerulescens) regularly breed cooperatively.

One characteristic of nesting falconids is division of responsibilities. Females are responsible for brooding and feeding the young as well as defending the nest. Males are entirely responsible for hunting from the time of courtship to about half-way through the nestling period, when the female begins to leave the nest and start hunting.

Mating System: monogamous ; polygynous ; cooperative breeder

Falconids breed once per year during the time of greatest prey availability, often between late winter and early summer. Females lay 1 to 7 (usually 2 to 4) buff eggs with dark red-brown speckles. Eggs are laid every-other day or sometimes every third day. If a clutch is lost within the first two weeks, many pairs will relay. Incubation lasts for 28 to 35 days, and the fledgling period lasts from 4 to 8 weeks. Unlike Accipitrids (Accipitridae), falconid chicks usually hatch synchronously. As a result, falconid chicks in a nest are usually roughly the same size, and siblicide is rare. Falconids usually begin to breed between ages 1 and 3. Most individuals are philopatric; they return to the area near where they hatched to breed.

Unlike most hawks (Accipitridae), falcons do not build nests (though caracaras do). Instead, falcons may arrange the substrate at a nest site such as a cliff to create a smooth depression for the eggs. Nest sites are variable both within and between species, and can include cliffs, tree cavities, epiphytes, the ground and buildings and other urban structures. Falcons frequently usurp nests built by other species, such as corvids and other raptors. Caracaras do build rudimentary nests of sticks, which they line with softer materials such as bark or wool.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (Internal )

Females lay 1 to 6 (usually 3 to 4) buff eggs with dark red-brown speckles. Eggs are incubated by the female for 28 to 35 days; generally smaller species have a shorter incubation period than larger species. The semi-altricial chicks usually hatch synchronously, and are brooded almost constantly by the female for the first 7 to 10 days. The female also feeds the chicks for the first part of the hatchling period, by tearing prey items into small pieces. The male provides all of the food for the female and the chicks until approximately half-way through the nestling period, at which time the female begins hunting as well. The chicks fledge after 28 to 30 days in small falcons, up to 49 days in the largest falcons and up to 8 weeks in caracaras. The parents continue to provide food for the fledglings for 2 weeks to several months after fledging.

Parental Investment: altricial ; male parental care ; female parental care