Falconidaefalcons(Also: falcons and caracaras)

Last updated:

Diversity

The Falconidae is one of two families within the order Falconiformes. Falconidae contains 11 genera and 64 species, and is divided into two subfamilies, Polyborinae (caracaras and forest-falcons) and Falconinae (true falcons and falconets).

Falconids can be found in most terrestrial habitats throughout the world, but the greatest diversity of falconids is found in South America and Africa. All falconids are able hunters that can take a variety of prey, including insects, birds, mammals, herpetiles and carrion. Most falconids are solitary and territorial, though a few species are colonial or semi-colonial. All but one species is monogamous, and pairs breed once per year, raising between one and six chicks. Both the male and female provide parental care, with the male providing the majority of food for the female and nestlings. ("Falcons and Caracaras (Falconidae)", 2002; "", 2003; Kemp and Newton, 2003; Sibley and Ahlquist, 1990; Snyder, 2001; White, et al., 1994)

Geographic Range

Falconids are native to terrestrial ecosystems worldwide, except in the high arctic and on Antarctica. Africa and South America host the highest diversity of falconids. ("Falcons and Caracaras (Falconidae)", 2002; Kemp and Newton, 2003; Snyder, 2001; White, et al., 1994)

Habitat

Falconids are found in nearly every terrestrial habitat, including desert, tundra, taiga, grasslands, savanna, scrub forest, chaparral, forest, mountains, coastal areas, wetlands, estuaries, lake shores, agricultural areas, suburbs and cities. The highest diversity of falconids is found in the tropics, in open rather than forested habitats, and in lowlands rather than at high elevations. Most species are adaptable to various habitats, as habitat structure and availability of nest sites appear to be more important than specific vegetation. A dramatic example of this adaptability are peregrine falcons (Falco peregrinus) and kestrels that successfully breed in cities, nesting on tall buildings and other man-made structures and hunting pigeons and other urban wildlife. Other species, including most forest-falcons in Polyborinae, require more specific habitat, such as undisturbed forest interiors. Migratory species often choose winter habitat that is similar in structure to their breeding habitat. Males, females and juveniles of some species may winter in different habitats, the juveniles taking advantage of habitats with abundant prey but an absence of nest sites. ("Falcons and Caracaras (Falconidae)", 2002; Cade, et al., 1996; Snyder, 2001; White, et al., 1994)

Physical Description

Falconids are medium-sized to large birds of prey (wingspan 55 to more than 125 cm, weight 28 to 2100 g), typically with hooked beaks, large brown eyes and a yellow cere, eyerings and feet. Falcons (Falconinae) are typically stocky birds with pointed wings, long toes with sharp talons, hooked, notched beaks, and brown, black, gray or white streaked or mottled plumage. Caracaras (Polyborinae) are smaller than falcons, have longer necks and legs than falcons, thicker, flatter talons, more rounded wings, a semi-bare face that is often brightly colored, and often glossy black plumage. Plumage of most falconids is lighter below and darker above. Individual species show variation from the basic structures that reflects the functions required by their habitat and prey. For example, the length and strength of the toes and beaks vary widely within the family and correspond to prey type. Bird predators have long toes, where as insect- and mammal-catching species have shorter, fleshier toes. Wing shape also varies; fast, open-country species have long, pointed wings, whereas forest-dwelling species have more rounded wings and longer tails.

Like other birds of prey, falconids exhibit reversed sexual size dimorphism (females are larger than males). This trait is most exaggerated in falconids that catch fast-moving prey, such as birds, and less pronounced in species that primarily eat carrion. In some species, females may also have a larger bill than males. Sexual dichromatism occurs in a few species of falconids. Male and female plumage are similar in most species, though male plumage may be somewhat brighter. Immature falconids typically exhibit plumage that is dull in color, often brownish with pale edges and more streaked than adults. Some species, such as gyrfalcons exhibit light and dark morphs. Falconids molt once per year, and immatures of most species attain adult plumage by the first annual molt.

Traits shared with Accipitrids, the presumed sister taxa of falconids include a fleshy cere covering the base of a strongly hooked beak, strong hallux (hind toe) opposing three forward toes, habit of capturing prey with feet, and reversed sexual size dimorphism (female larger than male).

Traits that distinguish this group include a tubercle (small, bony projection) in the nostril, structure of the syrinx, characteristic flight-feather molt pattern, tomial teeth on bill for killing and dismantling prey, chemical composition of eggshells, reddish (rather than blue or greenish) translucence of eggs when held up to light, and habit of killing prey with the beak (rather than squeezing with the feet). ("Falcons and Caracaras (Falconidae)", 2002; Kemp and Newton, 2003; Snyder, 2001; Wheeler and Clark, 1995; White, et al., 1994)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • male more colorful

Reproduction

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. ("Falcons and Caracaras (Falconidae)", 2002; Kemp and Newton, 2003; Snyder, 2001; White, et al., 1994)

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. ("Falcons and Caracaras (Falconidae)", 2002; Snyder, 2001; White, et al., 1994)

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. ("Falcons and Caracaras (Falconidae)", 2002; Snyder, 2001; White, et al., 1994)

Lifespan/Longevity

Estimates of annual adult survival ranges from 65 to 80 %. The highest mortality probably occurs during the first year. Some of the oldest known falconids include a crested caracara (Caracara cheriway) and a peregrine falcon (Falco peregrinus), both of which lived to 22 years old. ("Falcons and Caracaras (Falconidae)", 2002; Snyder, 2001)

Behavior

Falconids can be sedentary or migratory (or partially so). Of those species that do migrate, some fly long distances (up to 20,000 km) between breeding and wintering grounds, and others make only small shifts, such as changing elevation from a high-altitude breeding territory to a lower-altitude wintering ground where food is more abundant. Some species are partially migratory; only part of the population migrates when food becomes less abundant. For example, females of some kestrels migrate while the males stay on the breeding grounds year round.

Most species of falconids are diurnal, though some are crepuscular. Individuals usually have a regular spot where they return to roost at night. Falconids spend considerable amounts of time maintaining their plumage, preening and bathing in dust or water, presumably because the condition of their plumage affects their ability to catch prey. Falconids are generally strong, powerful fliers. Some of the most spectacular fliers are peregrine falcons (Falco peregrinus), which can reach speeds of up to 180 km per hour in a stoop (steep diving flight).

Most species of falconids are solitary and territorial. However, others are gregarious, flocking together opportunistically to feed, roost, breed or migrate. One species, red-throated caracaras (Ibycter americanus), live in cooperative groups and defend a communal territory. Falconid social behavior may change throughout the year, some species become more gregarious outside of the breeding season. ("Falcons and Caracaras (Falconidae)", 2002; Snyder, 2001; White, et al., 1994)

Communication and Perception

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. ("Falcons and Caracaras (Falconidae)", 2002; Snyder, 2001; White, et al., 1994)

  • Other Communication Modes
  • duets

Food Habits

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. ("Falcons and Caracaras (Falconidae)", 2002; White, et al., 1994)

Predation

Falconids do not have many natural predators. However, colonial-nesting and foraging species are known to cooperatively defend against potential predators, which include eagles. (White, et al., 1994)

Ecosystem Roles

As predators, falconids impact populations of their prey on a local scale. Falconids are also host to feather lice.

Black caracaras (Daptrius ater) have a mutualistic relationship with tapirs. The caracaras eat ticks off of the tapirs, which seem to solicit the caracaras by calling and laying down to have the ticks removed. ("Falcons and Caracaras (Falconidae)", 2002; Snyder, 2001; White, et al., 1994)

Economic Importance for Humans: Positive

Falcons have been serving falconers for as long as 2000 years. Falconry continues to be popular today, with as many as 20,000 practitioners worldwide. ("Falcons and Caracaras (Falconidae)", 2002; White, et al., 1994)

  • Positive Impacts
  • pet trade
  • controls pest population

Economic Importance for Humans: Negative

Falconids occasionally depredate livestock, poultry, pigeons and native game birds, leading to conflict with humans. ("Falcons and Caracaras (Falconidae)", 2002; White, et al., 1994)

Conservation Status

The most significant threat facing falconid populations today is habitat destruction due to intensified human land use, such as logging and clearing of forests. While habitat changes such as forest clearing favor some falconid species, other species that depend on intact forest habitat are declining as a result of development. Many falconid species suffered population declines during the 1960’s and 70’s as the result of poisoning from widespread organochlorine pesticide use. While use of organochlorine pesticides has been eliminated in many countries, it continues in some lesser-developed countries. Local threats to falconid populations include introduced predators, secondary poisoning (from poisons meant for other species), collision with man-made objects such as cars, windows and windmills, bird and egg collection for trade, and electrocution on power lines.

A few species of falconids have successfully adapted to urban landscapes. For example, peregrine falcons are able to nest on buildings, bridges and overpasses, and are able to achieve similar, and sometimes even higher reproductive success compared to pairs nesting in more natural landscapes.

One species of falconid has gone extinct in recorded history. Guadeloupe caracaras (Polyborus plancus lotosus) went extinct around 1600. Today, the IUCN lists 4 species as vulnerable and 6 species as near threatened. All species of Falconids are listed under CITES Appendix I or Appendix II. ("Falcons and Caracaras (Falconidae)", 2002; "UNEP-WCMC Species Database: CITES-Listed Species", 2003; Cade, et al., 1996; IUCN, 2003; Kemp and Newton, 2003; White, et al., 1994)

  • IUCN Red List [Link]
    Not Evaluated

Other Comments

The earliest fossils attributed to falconids were found in England, and date to 55 million years ago.

Red-throated caracaras, which prey on bee and wasp nests, are able to emit a powerful insect repellent that scatters angry wasps and bees, preventing them from attacking the bird. Crested caracaras (Caracara plancus) are the national emblem of Mexico. ("Falcons and Caracaras (Falconidae)", 2002; Kemp and Newton, 2003; White, et al., 1994)

Contributors

Alaine Camfield (editor), Animal Diversity Web.

Kari Kirschbaum (author), Animal Diversity Web.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

cooperative breeder

helpers provide assistance in raising young that are not their own

cosmopolitan

having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.

crepuscular

active at dawn and dusk

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

diurnal
  1. active during the day, 2. lasting for one day.
duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

piscivore

an animal that mainly eats fish

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scavenger

an animal that mainly eats dead animals

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

References

2003. E Dickinson, ed. The Howard and Moore Complete Checklist of the Birds of the World, Third Edition. London: Christopher Helm.

2002. Falcons and Caracaras (Falconidae). M Hutchins, J Jackson, W Bock, eds. Grzimek's Animal Life Encyclopedia, Vol. 8, Second Edition. Detroit: Gale Group.

2003. "UNEP-WCMC Species Database: CITES-Listed Species" (On-line). Accessed March 22, 2004 at http://www.cites.org/eng/resources/species.html.

Cade, T., M. Martell, P. Redig, G. Septon, H. Tordoff. 1996. Peregrine Falcons in Urban North America. Pp. 3-14 in D Bird, D Varland, J Negro, eds. Raptors in Human Landscapes: Adaptations to Built and Cultivated Environments. San Diego: Academic Press Inc.

Griffiths, C. 1999. Phylogeny of the Falconidae inferred from molecular and morphological data. The Auk, 116: 116-130.

IUCN, 2003. "2003 IUCN Red List of Threatened Species" (On-line). Accessed March 18, 2004 at http://www.redlist.org/.

Kemp, A., I. Newton. 2003. Falcons. Pp. 154-161 in C Perrins, ed. The New Encyclopedia of Birds. Oxford: Oxford University Press.

Sibley, C., J. Ahlquist. 1990. Phylogeny and Classification of Birds; A Study in Molecular Evolution. New Haven: Yale University Press.

Snyder, H. 2001. Falcons and Caracaras. Pp. 225-229 in C Elphick, J Dunning, D Sibley, eds. The Sibley Guide to Bird Life and Behavior. New York: Alfred A. Knopf.

Wheeler, B., W. Clark. 1995. A Photographic Guide to North American Raptors. San Diego, California: Academic Press, Inc.

White, C., P. Olsen, L. Kiff. 1994. Family Falconidae (Falcons and Caracaras). Pp. 216-247 in J del Hoyo, A Elliott, J Sargatal, eds. Handbook of the Birds of the World, Vol. 2. Barcelona: Lynx Edicions.