Animal Diversity Web

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)

• Biogeographic Regions
• nearctic
• palearctic
• oriental
• ethiopian
• neotropical
• australian
• oceanic islands

• Other Geographic Terms
• holarctic
• cosmopolitan

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)

• Habitat Regions
• temperate
• tropical
• terrestrial

• Terrestrial Biomes
• tundra
• taiga
• desert or dune
• savanna or grassland
• chaparral
• forest
• rainforest
• scrub forest
• mountains

• Wetlands
• marsh
• swamp
• bog

• Other Habitat Features
• urban
• suburban
• agricultural
• riparian

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)

• Other Physical Features
• endothermic
• bilateral symmetry

• 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)

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

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• oviparous

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)

• Parental Investment
• altricial
• male parental care
• female parental care

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)

• Key Behaviors
• flies
• diurnal
• crepuscular
• motile
• migratory
• sedentary
• solitary
• territorial
• colonial

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)

• Communication Channels
• visual
• acoustic

• Other Communication Modes
• duets

• Perception Channels
• visual
• tactile
• acoustic
• chemical

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)

• Primary Diet
• carnivore
  • eats terrestrial vertebrates
  • piscivore
  • eats eggs
  • insectivore
  • eats non-insect arthropods
  • scavenger
• herbivore
  • frugivore

• Foraging Behavior
• stores or caches food

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)

• Known Predators

  • eagles (Accipitridae)

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.

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.