Falcons and caracaras

(Falconidae)

Class Aves

Order Falconiformes

Suborder Falcones

Family Falconidae

Thumbnail description
Small to medium-sized largely diurnal raptors with strong feet, usually pointed wings, and sharply curved beaks; from scavengers to among the swiftest and, for their size, most powerful of avian predators

Size
5.5–25.6 in (14–65 cm); 0.06–4.6 lb (28–2,100 g)

Number of genera, species
10 genera; about 62 species

Habitat
Most habitats, from treeless desert and tundra to dry forest and rainforest, featureless plains to rugged gorges and escarpments

Conservation status
Vulnerable: 4 species; Near Threatened: 6 species; one subspecies Extinct

Distribution
Worldwide, except the Antarctic

Evolution and systematics

The relationship of falconids to other birds has long been unclear. Their similarity to the accipitrids (family Accipitridae, hawks and eagles) is obvious, and it has been suggested that they have morphological and anatomical links with the owls. Yet molecular evidence suggests that in both cases the resemblance is convergent; that they have evolved to look and behave in a similar fashion because of their similar lifestyles. One classification, based on DNA hybridization, groups them within the Ciconiiformes (herons, storks, and ibises). Nevertheless, in most modern classifications they are still placed with the accipitrids in the order Falconiformes.

There is no good fossil evidence to suggest where the family might have originated geographically. Africa now has the greatest diversity of falcons, but that does not necessarily reflect their past distribution or give clues about where they might have arisen. Contemporary caracaras and forest falcons (Polyborinae) are South and Central American, and there is no indication the subfamily was ever otherwise, so it seems reasonable to suggest they arose in the neotropics.

The earliest fossil attributed to the family was found in England and dated to 55 million years ago. Better-substantiated fossil members of the family have been reported from 36-million-year-old deposits in France. In the Americas, falconids have been identified from 23 million years ago, including a caracara-like form. The falcons, genus Falco, the largest group of falconids, are clearly closely related and are thought to have undergone rapid radiation and expansion early in the Pleistocene (about 1.85 million years ago), when the grasslands opened up.

Within the family, division into the two subfamilies is well supported but there is much argument over relationships within each. Nevertheless, each major region has its group of similar, presumably closely related forms (gray falcon [Falco hypoleucos], black falcon [F. subniger], brown falcon [F. berigora] and New Zealand falcon [F. novaeseelandiae] in Australasia) and there are a few groups of more widespread sister species (the desert falcons, kestrels, peregrines, and hobbies).

Physical characteristics

Falconids are readily recognizable as birds of prey and are likely to be confused only with the other family of diurnal raptors, the Accipitridae. Both have a fleshy cere atop a strong hooked beak, and a strong hallux (hind toe) that opposes three forward toes. Both families capture animals with their feet and, unlike most bird species, females are larger than males. The difference between the sexes is greatest in bird-eaters (female around 150% of male weight), intermediate in mammal-eaters, and least in insect-eaters and scavengers (females marginally heavier).

Differences between the families include several anatomical features, such as the structure of the syrinx, the fact that falconids kill with the beak or by the blow when they strike

(accipitrids squeeze with their feet), and eggs that have reddish translucence when held up to the light (accipitrid eggs are bluish or greenish).

Most falconids have strong needle-sharp talons. The exception is the caracaras, which have heavy but flatter talons for their more terrestrial, vulture-like lifestyle. Other structures also vary with lifestyle, form reflecting function. Hence, toes of bird-catching species are long and slender, mammal eaters have thicker toes, and snake eaters the shortest and thickest. Beaks also vary with prey: short and robust in most species, particularly deep in species that take large prey; longer and less powerful in carrion eaters. Fast aerial falconids of open country or those that migrate tend to have the longest, most pointed wings. Slower species tend to have slightly broader wings. Forest-dwelling species have short rounded wings and a long tail that gives them maneuverability in tight spaces.

Plumages tend to be fairly cryptic: shades of brown, black, and gray or white, often mottled or streaked. The caracaras, which tend to be mostly scroungers with no need for camouflage, are more colorful and some have raven-like, glossy black feathers with a green sheen. Most species have yellow soft parts (cere, narrow eye-ring, legs, and feet), occasionally gray or red. Caracaras and forest falcons are distinguished by obvious areas of featherless bright red or yellow skin around the face, more extensive in the more scavenging species.

The family is noted for its powers of sight, with an ability to detect the smallest movement at great distance. Most have rather large brown eyes; those living in dimly lit habitats or that regularly hunt into the evening tend to have the largest eyes.

Distribution

Except for the Antarctic and parts of the far high Arctic, the falcons alone are distributed worldwide. The remaining Falconinae, the falconets, are mainly tropical Spiziapteryx (1 South American species), Polihierax (1 African species; 1 Indian), and Microhierax (5 Asian species).

All 16 species of Polyborinae are neotropical, mainly South American, and do not venture beyond that region. These include caracaras Daptrius (2 species), Phalcoboenus (4), Polyborus(1), Milvago (2), laughing falcon Herpetotheres (1), and forest falcons Micrastur (6).

Of the Falconinae, several falcons migrate from one region to another (most from Eurasia to Africa; none to Australia).

Among breeding grounds, the species are distributed as follows, and some occur in more than one region: Australasia (8 falcons), African region (1 pygmy falcon Polihierax, 14 falcons), Central and South America (3 falcons), North America (9 falcons), and Eurasia (6 falconets, 11 falcons).

Individual species vary widely in the extent of their distribution. The peregrine falcon (Falco peregrinus, meaning the wanderer) is the most widespread of all, occurring almost everywhere habitat is suitable, with a few notable gaps such as New Zealand. The Seychelles (F. araea) and Mauritius (F. punctatus) kestrels are probably the most restricted in distribution, confined to some tiny islands of the Seychelles and Mauritius, Indian Ocean. The crested caracara (Polyborus plancus), found throughout South and Central America, has the most extensive range of the Polyborinae. The striated caracara (Phalcoboenus australis) and plumbeous forest falcon (Micrastur plumbeous) are very localized. Perhaps not surprisingly, all species with very limited distributions are listed as being threatened with extinction.

Several species extended their distribution in historical times because extra habitat was created for them or they adapted to disturbed habitats. One example is the Australian kestrel (F. cenchroides), which has established populations on Christmas Island, Indian Ocean, and Norfolk Island, southwest Pacific Ocean. The kestrel self-colonized both islands; the former by hitching a ride on warships operating in the area during World War II, the latter after the rainforested island was turned to farmland.

One species was purposely introduced and became established: the chimango caracara (Milvago chimango), endemic to southern South America, was translocated to Easter Island, South Pacific, in 1928 and is now common.

Habitat

As a group, the falconids occur in most major habitats around the world. They reach their greatest diversity near the tropics and only two species are found in the high Arctic (gyrfalcon F. rusticolis, peregrine falcon). Many species are quite adaptable and for them the structure of the habitat is more important than its individual components. For these species, habitat disturbance may not be important provided prey and nest sites are still available. For example, conversion of forest and woodland to farmland appears to have favored the Australian kestrel, but recent agricultural intensification has rendered some areas unsuitable again. Another example is the use of city canyons by peregrine falcons and several species of kestrel; cities and suburbs can offer nest sites, abundant prey (pigeons, starlings, rats, insects), and refuge from persecution.

Other species are more specialized. For example, several forest falcons need large tracts of more-or-less intact forest. Eleanora's falcon (F. eleanorae) nests on a few small quiet islands and islets, pockmarked with holes and ledges and sited on the migratory routes of small birds in the Mediterranean. In the nonbreeding season the population migrates to a very different habitat in the open woodlands and forests of Madagascar.

Typically, forest falcons and falconets require forest and forest clearings and edges. In contrast, falcons and caracaras favor open country, from grasslands to open woodlands and scrub. As always there are exceptions; the bat falcon (F. rufigularis) depends on forest edge, and the Seychelles kestrel lives in dense secondary forest.

In the nonbreeding season many species, such as Eleanora's falcon and several from high latitudes in the Northern Hemisphere, make drastic habitat changes. Annually, the entire population leaves breeding grounds made barren by the winter desertion of small birds or by snowfalls to fly across the globe to more productive zones. Other species make less drastic, more unpredictable shifts in distribution, such as local movements down from the mountains to winter in milder coastal areas. The African pygmy falcon (Polihierax semi-torquatus) leaves more arid parts of its range when the season is particularly dry. In some species there may be no shift in mild winters, or only part of the population may leave to winter elsewhere. In many species, such as several kestrels, females are most likely to depart the breeding grounds for the winter; males will stay if they can support themselves.

Behavior

Typically, falconids are active by day, but several species hunt crepuscularly. For example, the Eurasian hobby (F. sub-buteo) chases moths after dusk, and peregrine falcons hunt shearwaters as they return to their holes well after dark. At night they usually roost at a regular roost, sheltered from the prevailing elements and safe from predators. Even on migration, the same roosts are often used year after year.

Some species are resident, others are migratory or partially migratory (in areas where winter is harsh, part of the population migrates). Distances traveled range from 6,000–12,000 mi (10,000–20,000 km) (Arctic peregrine falcons) down to very local shifts (e.g., Australian peregrine falcons), both to areas where prey is more available. One of the most dramatic examples is the movement of several falcons from Eurasia and the Mediterranean to Africa and Madagascar, to feed on vast swarms of termites and ants that arise during the wet season. Some species gather in flocks and move en masse (red-footed falcon F. vespertinus), others find their way individually. Juveniles of most species disperse after their post-fledgling dependency, except for juveniles of the red-throated caracara, that may join the communal group. In all species studied, juveniles are more dispersive than adults, and females tend to depart earlier and move farther than males.

Although falcons are typically viewed as solitary creatures, many species are gregarious and may flock together to feed, roost, breed, or migrate. Some flock opportunistically (many kestrels), others live in cooperative groups as a way of life (red-throated caracara Daptrius americanus). Still others live in loose groups but don't directly assist each other (Eleanora's falcon). At the other end of the spectrum are purely solitary species that are highly territorial year-round (collared falconet Microhierax caerulescens).

Falconids have rather harsh voices, at least for longer-distance communication. For more intimate contact they make softer sounds. Forest falcons and laughing falcons call at dawn (and again at dusk), presumably to advertise that they are still present on their territory in the dense forest. Caracaras are also rather vocal, particularly when annoyed over food or other territorial disputes, throwing their heads back to release the far-carrying calls for which they are named. By contrast, falcons can be rather silent, mainly heard when humans disturb a nest and the falcons call in defense (usually a strident kak kak kak kak that is higher pitched in smaller species).

Feeding ecology and diet

Feeding ecology is a better-known aspect of falconoid ecology, mainly because they eat large prey and produce pellets (wads of indigestible parts of the prey—fur, feathers, scales, bone—that are regurgitated once a day or so) that can be analyzed for the prey they contain. Pellets build up under nests and roosts and make interesting study.

Falconids are predatory meat eaters, yet some also scavenge and the caracaras eat some vegetable matter. Several, especially the more aggressive species (black falcons F. subniger, and caracaras), are not above stealing prey from other raptors,

herons, and others. Some species are specialized; for example, the peregrine feeds mainly on birds and the laughing falcon on snakes, but both take a variety of species in those prey groups. The gyrfalcon takes ground-dwelling creatures such as medium-sized mammals and terrestrial birds. Other species spread their diet over a range of prey groups. Caracaras can kill prey as large as lambs and capture birds on the wing, but mostly they scrounge for carrion (especially its maggots) and horse dung, and take easier prey such as earthworms, maggots, lizards, insects, nestling birds, frogs, and fish. Forest caracaras (Daptrius) eat fruit, and wasp and bee nests, for which they seem to have a repellant that protects them from stings from the angry insects. The black caracara (D. ater) picks ticks off tapirs, which appear to solicit the caracaras by calling and then lying down to have the ticks removed. Many species hawk moths in the evening and insects on the wing, especially when the insects swarm, such as after rain and around water. In the breeding season most species concentrate on live prey. Juveniles tend to capture easier prey (such as insects) than do adults.

Hunting methods are as varied as the diet. Bird-catching falcons (even diminutive falconets) are the most spectacular hunters, sometimes catching prey as large as themselves at breathtaking speed, either in a direct tail chase or by diving from height to strike with great force. Other species capture prey on the ground or as it flushes. Most kestrels hover (giving them a fixed aerial vantage point from which to spot and drop onto prey) or swoop down from a perch. Some longerlegged species run over the ground after insects.

Falcons tend to hunt in the open, by sight. Forest falcons make greater use of sound to locate prey in the dim dense forest, and have a circle of stiff feathers around the ear openings to funnel sound to the ears. All species use the element of surprise to improve their success rate.

Most species hunt alone, occasionally as cooperative pairs (several falcons), and a few forage cooperatively in groups (red-throated caracara). Several species use herds, tractors, fires, cars, and other birds to flush prey. Most if not all falcons cache a little prey in excess of their immediate needs, placing it in a rock crevice or under a grass tussock for later retrieval.

Reproductive biology

Most falconids breed once a year in a traditional breeding territory. Territories range from a few square yards (meters) for colonial species like the lesser kestrel (Falco naumanni) and Eleanora's falcon, to 400 mi² (1,000 m²) for the solitary nesting gyrfalcon. Spacing between pairs depends on food and nest availability. Typically falconids are monogamous, nesting as solitary faithful pairs. Yet many variations in breeding arrangements found in other birds are present in the family. About 10% of falconids are colonial or semicolonial and nest in loose groups. The red-throated caracara has a more cooperative approach to group living; only the alpha pair breeds and it is assisted in feeding and protection by other group members. Some peregrine falcon pairs in France had an extra female who appeared to help with feeding, leading to greater breeding success at assisted nests. Pygmy falcons are sometimes polyandrous, with more than one male attending the nest and presumably having a chance to father young.

Most species have courtship rituals involving fancy flying and increased calling. Except for the caracaras, falconids do not build nests. Rather they use a tree hole or cliff cavity, an open stick or enclosed woven nest of another species, an epiphyte, or some other suitable situation. Caracaras build an untidy nest of sticks or dried grass, sometimes lined with wool or grass.

Caracaras, forest falcons, and many of the falcons lay two to three red-brown blotched buff eggs. The laughing falcon lays a single dark egg; the falconets and some species that nest in harsher environments lay three to four or more eggs. Some falcons (gyrfalcon, many kestrels) lay a much larger clutch when conditions are good than when they are poor; other species are more conservative in the size of their clutch (brown falcon, peregrine falcon, island kestrels). Widespread species have smaller clutches in milder parts of their range.

Typically, there is a division of roles: the female does most of the incubation and the male catches prey for her and the chicks, at least for the first part of the nestling period when she is brooding. Incubation is quite fixed for individual species and ranges from about 28 days for smaller species to 35 days for the gyrfalcon. The length of the nestling period is also related to size, with smaller species (falconets and small falcons) taking four weeks, larger species seven or eight weeks (gyrfalcons and caracaras). The nestlings grow rapidly and at fledgling are as heavy as the adults but with flight feathers (wing and tail) not quite fully grown. Fledglings are dependent on adults for variable periods, seemingly longer in species that hunt difficult or scarce prey.

Conservation status

Falcons and caracaras have a long history of persecution for their perceived impact on livestock. Particularly in the 1960s and 1970s, organochlorine pesticides (DDT, dieldrin, and others) had a very real impact on eggshell thickness and the mortality of some species, leading to massive population declines. Yet the group's remarkable resilience is illustrated by the fact that no species are currently listed as Endangered or Critically Endangered, the two highest-risk categories used by the World Conservation Union (IUCN).

Only one falconid has become extinct in historical times: the Guadeloupe caracara (Polyborus plancus lutosus) of Isla Guadeloupe, Mexico. It is generally regarded as a subspecies of the crested caracara (P. plancus), which is widespread on the Central and South American mainlands, but some taxonomists consider it a full species. Regardless, settlers persecuted the caracara and it has not been seen since 1900. Its demise must have been accelerated by the denuding of the island's dense vegetation by goats.

The main threat for falconids in general is widespread habitat destruction by logging, clearing and burning of forests and woodlands, and intensifying land-use by humans for agriculture, grazing, subsistence hunting, or housing. Local impacts include introduced predators, pesticides, and trade in birds and eggs. Threats to survival of the IUCN-listed species are typical of those facing most falconids.

Four species, the Plumbeus forest falcon and three kestrels, are listed as Vulnerable; that is, they face extinction in the medium-term future if factors causing their vulnerability are not reversed or held at bay. All three kestrels—Seychelles, Mauritius, and lesser kestrels—are found in the African region. The lesser kestrel is a winter migrant to the region, South Africa in particular. In 2000 its world population was estimated to have declined by about 50% in the past 50 years, recovering to 80% of former numbers in the past decade. Deforestation and urbanization of its extensive breeding grounds in western Europe and elsewhere, and intensification of agriculture in its breeding and wintering grounds are believed to be major causes of decline. The other two kestrels are confined to islands where their forest habitat is decimated and introduced predators raid their nests. Conservation actions such as restoring and predator-proofing nest sites are helping all three species. As a result of a captive breeding-forrelease program and management in the wild, the Mauritius kestrel was recently down-listed from Endangered because its population has undergone a spectacular recovery, from about four wild birds in the 1970s to more than 500 in 2000.

Another six species are considered Near Threatened. The striated caracara occurs in low numbers on islands and islets off southern Argentina and Chile, including the Falklands where it was persecuted for its occasional attacks on weak or stranded sheep. At present it seems to be free of major threats but remains vulnerable because of its small population. The five remaining species are not well known but are presumed to have a small total population. The two falconets are Asian in distribution, where habitat clearing is a major problem. The white-rumped falcon (Polihierax insignis) was once widespread and common in the grasslands and deciduous forests of Thailand, Laos, Cambodia, and Vietnam, and may still survive in extensive areas that remain uncleared. The white-fronted falconet (Microhierax latifrons) has a very restricted distribution centered on Sabah, Malaysia; an ability to survive in disturbed habitats may allow it to persist. Past habitat clearance, persecution by farmers and pigeon and poultry keepers, and egg destruction by possums introduced from Australia have caused concern for the New Zealand falcon, but population trends are unknown. The gray falcon is thinly scattered across vast spaces of arid and semiarid Australia and, while it may have suffered some small past contraction in range from habitat loss to grazing by livestock, its population is thought to be stable. Similarly, the taita falcon (F. fasciinucha) occurs in naturally low densities in scattered gorges and escarpments from Ethiopia to South Africa, and no major threats are apparent.

Regional conservation initiatives have had some success; for example, reserves such as the Snake River Bird of Prey Conservation Area in Idaho. There, 800 pairs of 15 species nest and another nine use the park to winter or stop over on migration. Guarding nests at risk from egg collectors and falconers, and fostering nestlings into safer nests bolsters populations. In recent decades, education and promotion has generally increased tolerance of predatory birds and appreciation of their place in nature. Many falconids, such as the peregrine falcon, bat falcon (F. rufigularis), merlin F. columbarius), and various kestrels have moved into suburbs and cities where they hunt in the urban spaces and city skies, and nest in parklands and on buildings.

Significance to humans

Falconids have had a long association with people, and tend to elicit a strong response as friend or foe. They are much admired for their hunting prowess, flying skills, and keen sight, and appear as icons and in the legends and folklore of many cultures. In ancient Egypt, Horus the falcon god was ubiquitous, and as a hieroglyph, Horus represented the king. Falcons (Lanner F. biarmicus, Barbary falcon F. peregrinus pelegrinoides, a desert race of the peregrine, common F. tinnunculus and perhaps lesser kestrels) were buried in tombs, often mummified. At about the same time (2000 b.c.) or earlier, falcons were used to capture meat for humans. The first known falconry was practiced in Asia, from which it spread. It was most popular in Europe in medieval times (twelfth century), when kings, merchants, and even nuns kept trained falcons. Some of the jargon, such as haggard (a wild-caught adult falcon), has become part of everyday language. Today falconry is still popular where it is not outlawed by wildlife-protection legislation, particularly in the Middle East. Falconids are still significant to some indigenous peoples as totems and in legend. For similar reasons, they appear as symbols of strength, courage, or speed on crests and in logos and product names.

Paradoxically, often falconids are hated because of their depredations on livestock, poultry, pigeons, and even native birds. This is most often a case of misunderstanding of their role in nature and an exaggeration of their impact.

Because pesticide use caused it to vanish from vast areas of its natural range, the peregrine falcon became a flagship of the conservation movement. A concerted effort restored the peregrine and other affected species to much of their range. Although many falconids have adapted to altered environments and human activities, they remain charismatic symbols of a natural world.

Species accounts

List of Species

Crested caracara

Polyborus plancus

subfamily

Polyborinae

taxonomy

Polyborus plancas J. F. Miller, 1777, Tierra del Fuego. About three or four extant subspecies.

other common names

English: Common caracara, Guadeloupe caracara; French: Caracara huppé; German: Schopfkarakara; Spanish: Caracara Carancho.

physical characteristics

19–23 in (49–59 cm); in Panama male 1.8 lb (835 g), female 2.1 lb (955 g); larger in Chile and Peru 2.5–3.5 lb (1,150–1,600g). A distinctive heavy-beaked falconid with a laterally flattened head, black cap with slight crest, and a bare red face; longlegged and somewhat terrestrial. Mantle, rump, throat, and vent are white or buff and finely marked with black; rest of back is brown-black and finely marked with white or buff; breast is brown-black; tail is barred black and buff with black wide-barred tip. Juvenile is browner and more streaked. Races differ somewhat in size and color.

distribution

Central and South America from the southern United States (Texas to Arizona, and Florida) to Tierra del Fuego and the Falkland Islands.

habitat

Typically lowland open and semiopen country: grazing land, pasture, river edge. Also Patagonian river valleys, shrub steppe, and grassy foothills. Increasingly moving into uplands of Colombia and Ecuador.

behavior

Gregarious, gather at carcasses. Outside the breeding season they roost communally in the tops of isolated trees. Quite vocal, with a loud raucous territorial call made in characteristic pose with head thrown far back. Some local movements, but largely sedentary.

feeding ecology and diet

Among the most opportunistic of raptors. Walks over ground and through shallow water in search of prey; arrives at carcasses before vultures. Typically feeds on carrion, road kills, and dead and dying fish and livestock. Occasional live prey includes turtles, iguanas, snakes, crabs, earthworms, caterpillars, and beetles. Raids nests of passerines and other caracaras, and egret and spoonbill colonies. Aggressive; steals prey from other caracaras and raptors; pursues pelicans until the pelicans regurgitate. Eats coconut flesh at harvest in Guyanan plantations.

reproductive biology

Breeds as solitary pair over a prolonged season; occasionally two clutches in same year. Builds a large rough lined or unlined nest of sticks on top of cactus or palms, on dense tangles of tree branches, or on the ground. The usual clutch is two eggs; incubation is about a month. Fledglings remain with adults for perhaps three months.

conservation status

Not threatened. Generally common and locally abundant. Some local persecution and population decreases where they are poisoned and shot for predation on lambs. Habitat loss of farmland to citrus plantation threatens Florida population, but elsewhere conversion of forest to ranch land has helped species expand its distribution.

significance to humans

The caracara is the national bird of Mexico, a nod to Aztec legend.

Laughing falcon

Herpetotheres cachinnans

Subfamily

Polyborinae

taxonomy

Herpetotheres cachinnans Linnaeus, 1758, Surinam. Three sub-species usually recognized.

other common names

French: Macagua rieur; German: Lachfalke; Spanish: Halcón Reidor.

physical characteristics

17.7–20.9 in (45–53 cm); male 1.2–1.5 lb (565–690 g), female 1.4–1.8 lb (625–800 g). A distinctively patterned, large-headed,

black-masked falconid unlike any other, with short wings and long tail. Head and underparts cinnamon-buff to white, with a wide black mask from eyes to hindneck. Upperparts black-brown. Stout legs and short toes. Juvenile has dark feathers edged rufous or buff. Races vary in size and color.

distribution

Central and South America, from Mexico to Paraguay and northern Argentina.

habitat

Tropical and subtropical forest, near openings, tracks, or edge, and open forest. Mainly in lowlands.

behavior

Has very large home range for its size, estimated at 6,200 acres (2,500 ha) in continuous forest, less in more disturbed habitats. Thought to be sedentary.

feeding ecology and diet

Feeds almost exclusively on snakes that are terrestrial and arboreal, venomous and harmless. Occasionally takes birds and bats and, in disturbed areas, reptiles, rodents, and fish. Hunts from a perch where it sits in wait for long periods with head slightly bowed.

reproductive biology

Nests as solitary pair that duets ("laughs") near nest at dawn and dusk. Lays single dark brown egg in trees or cliff cavities, stick nests of another species, or on epiphytes. Nestlings fledge at about eight weeks and stay with parent for some months.

conservation status

Not threatened. Uncommon or fairly common throughout much of their extensive range.

significance to humans

Of traditional significance to local Indians.

Plumbeous forest falcon

Micrastur plumbeus

subfamily

Polyborinae

taxonomy

Micrastur plumbeus W. L. Sclater, 1918, Río Bogotá, Ecuador. Monotypic.

other common names

English: Sclater's forest falcon; French: Carnifex plombé; German: Einbinden-Waldfalke; Spanish: Halcón-montés Plomizo.

physical characteristics

11.8–14.6 in (30–37 cm). Goshawk-like falcons with short wings, long tail, and long legs. A bare area of bright yellow skin surrounds the eyes and links the species with the caracaras. Upperparts slate gray. Underparts: gray throat grades to a white breast and belly barred with black. Tail distinctive: black tipped with white and a single white band mid-tail. Juvenile has fainter barring to underparts.

distribution

Restricted in distribution: from Cauca and Nariño of southwest Colombia to Esmereldas, northwest Ecuador.

habitat

Wet forest interiors of the lowlands and foothills of the Pacific slope.

behavior

Little known. Presumed to be sedentary.

feeding ecology and diet

Almost unknown. Land crab and lizard in one stomach. Hunts accipiter-like within forest, with short bursts of great speed and agility, and may also run over ground. May follow army-ant swarms, catching small animals that they flush, as do other Micrastur.

reproductive biology

Unknown. Nests as solitary pair probably in tree holes, as do other Micrastur.

conservation status

Vulnerable. Logging increasingly removes undisturbed closed-canopy forest on which the species depends. Infrastructure, particularly roads, has opened the region to agriculture, mining, and exploitation by international interests. Few pairs have ever been found and the species' secretive nature makes it impossible to know the population size.

significance to humans

None known.

Spot-winged falconet

Spiziapteryx circumcinctus

subfamily

Falconinae

taxonomy

Harpagus circumcinctus Kaup, 1852, Chile; error, Mendoza, Argentina. Monotypic.

other common names

French: Carnifex à ailes tachetées; German: Tropfenfalke; Spanish: Halconcito Argentino.

physical characteristics

11.0–13.0 in (28–33 cm); about 3.5 oz (100 g). Female larger than male. A slight short-winged, long-tailed forest dweller. Head, back, and wings gray-brown; a pale streak that extends back from above the eye, black ear coverts and moustachial streak form a characteristic pattern. Shoulders and wing spotted conspicuously with white. Underparts pale gray, narrowly streaked with brown. Central tail feathers black, remainder

barred with white to form wide black bars. No distinctive juvenal plumage (unlike other falconids).

distribution

South America: eastern Bolivia, through Paraguay to north and central Argentina.

habitat

Savanna, scrubby woodland, and semidesert.

behavior

Sedentary. Roosts in communal nests of monk parakeets (Myiopsitta monachus) in winter, even when the nests are occupied by parakeets.

feeding ecology and diet

Hunts mainly birds, some as large as they are, and lizards and insects such as locusts and cicadas. Bird prey includes nestling and adult monk parakeets.

reproductive biology

Nests as solitary pair in about November–December in woven nests of other species such as cachalotes (Furnariidae) and colonial monk parakeets; falconets enlarge the nest and entrance. In Argentina, 15 of 70 parakeet nests (21%) had nesting pairs of falconets. Lays clutches of two to four eggs; incubation period is unknown; young fledge after about 33 days.

conservation status

Not threatened. Status is unknown but habitat is not seriously degraded.

significance to humans

None known.

White-fronted falconet

Microhierax latifrons

subfamily

Falconinae

taxonomy

Microhierax latifrons Sharpe, 1879, Lawas River and Lumbidan, Borneo. Monotypic.

other common names

French: Carnifex à ailes tachetées; German: Tropfenfalke; Spanish: Halconcito Argentino.

physical characteristics

5.9–6.7 in (15–17 cm); 1.2–2.3 oz (35–65 g). Female larger than male. The second smallest falconid. Small, swift, and powerful for its size. Upperparts mainly black; underparts white with light tan wash to belly. Black eye stripe. Forehead, crown, and cheek white in male, chestnut in female. Juvenile similar to adult female.

distribution

Northern Borneo: Sabah and far northeast Sarawak.

habitat

Open forest and forest clearings and edges, up to about 3,900 ft (1,200 m).

behavior

Sedentary.

feeding ecology and diet

Hunts from perch to snatch prey from the air and tree canopies. Mainly large insects such as bees, moths, cicadas, butterflies; sometimes birds and perhaps lizards and bats. May hunt in family parties and feed communally, sharing prey.

reproductive biology

Little known. Nests as solitary pairs in sites such as barbet and woodpecker holes in March–April.

conservation status

Listed as Near Threatened because of its restricted range and uncertain status. Forest clearing is a threat. Nevertheless, the species appears to be fairly common and copes with some disturbance of its habitat.

significance to humans

None known.

Fox kestrel

Falco alopex

subfamily

Falconinae

taxonomy

Tinnunculus alopex Heuglin, 1861, Gallabat, Sudan. Monotypic.

other common names

French: Crécerelle renard; German: Fuchsfalke; Spanish: Cernícalo Zorruno.

physical characteristics

13.8–15.4 in (35–39 cm); 8.8–10.6 oz (250–300 g). A large deep-chestnut kestrel with long broad wings and long tail. Chestnut all over, streaked with black. Juveniles are more heavily marked. Unlike most kestrels, sexes indistinguishable by color but female larger than male.

distribution

Central Africa: from Senegambia east to Red Sea, Ethiopia, south to northeast Zaire, northwest Kenya, and northeast Uganda.

habitat

Cliffs, rocky outcrops, and hills adjoining open arid savanna.

behavior

Moves south from more arid parts of range in dry season (October to March) to attend bush fires; with rains, returns north to nest. Elsewhere appears sedentary.

feeding ecology and diet

Hunts large insects, small mammals and birds, and lizards. Drops onto prey from perch or from hover, or snatches from the air in direct flight (termites). Said to remain on the wing for long periods. Follows fires to catch animals flushed by the flames.

reproductive biology

Nests semicolonially, 20–25 pairs in proximity on a rock face. Lays about March to May in a shallow scrape on a ledge. Clutch size two or three.

conservation status

Not threatened. Species little known but thought to be secure. Human exploitation and savanna degradation may be a threat.

significance to humans

None known.

Amur falcon

Falco amurensis

subfamily

Falconinae

taxonomy

Falco vespertinus var. amurensis Radde, 1863, Zeya River, Amurland. Sister species to very similar red-footed falcon F. vespertinus. Monotypic.

other common names

English: Manchurian, Amur, or eastern red-footed falcon; French: Faucon de l'Amour; German: Amurfalke; Spanish: Cernícalo del Amur.

physical characteristics

11.0–11.8 in (28–30 cm); male 3.4–5.5 oz (95–155 g), female 3.9–6.7 oz (110–190 g). A colorful little falcon with unusual red legs, cere, and eye ring. Male mostly slate gray with contrasting chestnut lower belly, undertail coverts, and thighs. Female very different: upperparts gray; underparts whitish streaked and chevroned with black. Juvenile similar to adult female but with rufous edging to upperparts.

distribution

Breeds in southeast Siberia and from northeast Mongolia to Amurland, south into northern and eastern China and North Korea, occasionally northeast India. Winters in southern Africa, mainly from Malawi to Transvaal.

habitat

Breeding grounds: open woodland and woodland (coniferous and deciduous) margins and marshes, likes mature trees and avoids treeless areas. Wintering grounds: savanna and grassland with clumps of trees.

behavior

Whole population migrates from eastern Asia to southern Africa, often in large groups, sometimes with other small falcons. Leaves Asia in September, begins arriving in Africa in late November. In Africa, roosts at traditional sites in groups of trees, used by hundreds to thousands of birds. Returns to Asia, departing mainly March, arriving mainly April.

feeding ecology and diet

Feeds on insects such as locusts, grasshoppers, and beetles, and on small birds and occasionally amphibians. Hunts, often around dusk, from perch to capture prey in air, less often on ground, sometimes hovers. Outside breeding, gathers in flocks to feed on termite and ant swarms often associated with rain storms.

reproductive biology

Nests annually as solitary pair or in small colonies, in old corvid nests or tree holes. Lays in May–June; usually three or four eggs; incubation about 28–30 days; fledges at about one month.

conservation status

Not threatened. Thought to be common, at least locally.

significance to humans

None known.

Brown falcon

Falco berigora

subfamily

Falconinae

taxonomy

Falco berigora Vigors and Horsfield, 1827, New South Wales.

other common names

English: Brown hawk; French: Faucon bérigora; German: Habitchfalke; Spanish: Halcón Berigora.

physical characteristics

16.1–20.1 in (41–51 cm); male 0.7–1.3 lb (316–590 g), female 0.9–1.9 lb (430–860 g). A medium-sized long-legged, buteo-like falcon. Adults extremely variable: from tan and buff to

chocolate brown with variable white underparts (males tend to have more white), to near black all over (with some barring visible in wing and tail). Juveniles brown with buff touches to forehead, nape, and vent. Some regional variation in predominant color. Tend to be darker in humid areas, paler in arid areas, smaller in tropics, larger in temperate zone.

distribution

Australia and New Guinea, except highlands.

habitat

Open woodland, savanna, grassland, farmland, and desert up to about 6,600 ft (2,000 m).

behavior

Adults sedentary. Gathers in sometimes large flocks post-breeding, especially at fires and locust and mouse plagues, sometimes with other raptors.

feeding ecology and diet

Versatile and opportunist hunter: takes prey from perch, hover, in direct flight, or running over the ground. Occasionally robs other raptors. Attracted to fires, cattle herds, farm machinery, and livestock for the animals they flush. Pairs occasionally hunt cooperatively. Feeds on fresh carrion but takes mostly live prey: mammals, birds, reptiles (especially snakes), amphibians, and large insects; rarely crabs and fish.

reproductive biology

Breeds annually as solitary pair in stick nest of mainly corvids, and other raptors and magpies Gymnorhina tibicen; rarely on a man-made structure, tree fern, tree hole, cliff, or termitarium. Lays mainly August–September in south, earlier in north. Clutch 2–3, mostly three; incubation 33 days; young fledge at five to six weeks.

conservation status

Not threatened. Generally common and extremely widespread. Expanded into forested areas turned to farmland and open woodland.

significance to humans

Traditional significance and food to some aboriginal tribes, but practice largely lapsed.

Gyrfalcon

Falco rusticolis

subfamily

Falconinae

taxonomy

Falco rusticolus Linnaeus, 1758, Sweden. Monotypic (no sub-species).

other common names

English: Gyrfalcon; French: Faucon gerfaut; German: Gerfalke; Spanish: Halcón Gerifalte.

physical characteristics

Male 18.9–24.0 in (48–61 cm), female 20.1–25.2 in (51–64 cm); male 1.8–2.9 lb (800–1,325 g), female 2.2–4.6 lb (1,000–2,100g). Largest of the falconids and the only white falcon. Highly variable plumage: from nearly pure white through various barred, chevroned, and streaked gray plumages to nearly uniform dark gray-brown. Adults have bright yellow legs and feet. Juveniles tend to be slightly browner and more heavily streaked; pale gray legs and feet. White form usual in high Arctic; dark form in Labrador; gray forms predominate in Iceland; mostly gray individuals grading to equal numbers of white individuals from west to east across Russia and Siberia.

distribution

The most northern of all diurnal raptors. Breeds around the Arctic circle: Iceland, Greenland, North America, and Eurasia; winters farther south.

habitat

Fairly uniform habitat: tundra and taiga, from sea level to about 4,600 ft (1,400 m), ice bound and snow covered much of the year. Favors rivers and seacoasts, also mountains. Winter migrant to ice edge, farmland, agricultural land, and steppe.

behavior

In populations below 70° north many birds are resident, especially adult males. Migratory above 70° north, moves mainly but not only south to over-winter in warmer areas where prey is plentiful, mostly north of 40° north. Juvenile tracked with satellite transmitter from Alaska to Russia and back.

feeding ecology and diet

Hunts mostly ground-dwelling birds and mammals, such as ptarmigan, grouse, ground squirrels, and lemmings. Mostly flies low and fast to surprise and flush prey; occasionally takes birds after pursuit on the wing, and lifts waterfowl and shore-birds from water.

reproductive biology

Breeds annually as solitary pairs from March to July. Lays eggs in depression on cliff ledge, large stick nest of another species, or man-made structure. High variation in clutch size and nesting success, depending on prey availability; clutch usually three

or four but up to seven; incubation 33–36 days; fledges at about seven weeks.

conservation status

Not threatened. Naturally uncommon but can be locally common. Its preference for remote habitat gives it some protection from threats to many other raptors. Fur trappers in Arctic Russia may kill 1,000–2,000 annually, some are taken by egg collectors and falconers.

significance to humans

Prized for falconry, but probably small numbers taken from wild and are now bred in captivity for that purpose.

Peregrine falcon

Falco peregrinus

subfamily

Falconinae

taxonomy

Falco peregrinus Tunstall, 1771, Great Britain. About 18 sub-species.

other common names

English: Duck hawk; Barbary falcon, Kleinschmidt's falcon, Peale's falcon; French: Faucon pèlerin; German: Wanderfalke; Spanish: Halcón Peregrino.

physical characteristics

13.4–19.7 in (34–50 cm); 1.1–3.3 lb (500–1,500 g); female considerably larger than male (15–20% larger; 50% heavier). Size and color varies according to subspecies: largest is Peale's falcon (F. p. pealei) of coastal North America and the Aleutian Islands; smallest are desert forms of Eurasia and Africa. A handsome, powerful falcon with pointed wings, a rather short tail and a black-helmeted head. Upperparts blue-black to charcoal; underparts white to rufous with black broken bars. Juveniles (first year) are browner, with streaking to underparts. Subspecies tend to be darkest in humid areas, palest in deserts.

distribution

Perhaps the widest breeding distribution of any bird. Almost worldwide, on all continents except the Antarctic and many oceanic islands (such as Fiji); notably absent from the high Arctic (Iceland, Newfoundland) and New Zealand.

habitat

Among the most variable of all birds, from the hot tropics to cold coasts and islands, dry deserts and rugged cliff lines to forest and flat treeless tundra, from sea level to about 13,000 ft (4,000 m).

behavior

Many Northern hemisphere populations are long-distance migrants, moving south for the winter, stopping to rest and eat en route, with the most northern birds often travelling farthest south (for example, from Greenland to extreme southern South America). In Southern hemisphere and at mid-latitudes, adults are mainly resident year round.

feeding ecology and diet

A specialist hunter of birds caught in flight. Attacks from a perch or the air, sometimes in a spectacular stoop at great speed to strike prey in mid-air, less often on the ground or in water. Favors flock species, particularly pigeons and doves,

parrots, auks and petrels, European starling (Sturnus vulgaris). Occasionally also mammals such as rabbits, voles, bats, large insects, and (rarely) reptiles and fish. Takes prey up to 4.4 lb (2 kg). Pairs occasionally hunt cooperatively, one splitting a flock and the other following to catch the scattering birds unawares.

reproductive biology

Breeds annually as solitary pair, details depending on region. Lays eggs usually in late winter to spring. Does not build a nest, rather makes a shallow scrape in the substrate of the nest, which is most often on a cliff ledge or in a pothole or cave; also on buildings and bridges, on the ground (in predator-free parts of its range such as the Baltic bogs), in large abandoned stick nests of another species (Australia, Germany), or a large tree hole (mainly Australia). Clutch is larger in Northern hemisphere: usually three or four eggs in the Arctic and two or three in Africa and Australia. Incubation lasts about 30–33 days and chicks fledge when they are about five to six weeks old.

conservation status

Not globally threatened. Populations plummeted in the 1960s and 1970s from ill effects of chlorinated hydrocarbon pesticides used in griculture. After widespread banning of the chemicals beginning in the 1970s, most populations have recovered, some assisted by releases of captive-bred birds. Population numbers typically very stable. A few island subspecies are rare but may always have been so. Still persecuted by keepers of racing pigeons.

significance to humans

Where falconry is legal, the peregrine is a bird of choice. During the pesticide era, the species became a flagship species for the conservation movement and remains a charismatic reminder of that time.

Resources

Books

BirdLife International. Threatened Birds of the World. Barcelona and Cambridge: Lynx Edicions and BirdLife International, 2000.

Brown, L. H., E. K. Urban, and K. Newman. The Birds of Africa. Vol. 1. London: Academic Press, 1982.

Cade, T. J. Falcons of the World. London: Collins, 1982.

Cade, T. J. "Progress in Translocation of Diurnal Raptors." In Raptors at Risk, ed. R. D. Chancellor and B.-U. Meyburg. Berlin and London: World Working Group on Birds of Prey and Hancock House, 2000.

Clum, N. J., and T. J. Cade. "Gyrfalcon Falco rusticolus." Birds of North America. No. 114. 1995.

Cramp, S., ed. The Birds of the Western Palearctic. Vol. II, Hawks to Bustards. Oxford: Oxford University Press, 1980.

del Hoyo, J. A., A. Elliot, and J. Sargatal, eds. Handbook of the Birds of the World. Vol. 2. New World Vultures to Guineafowl. Barcelona: Lynx Edicions, 2000.

Eastham, C. P., J. L. Quinn, and N. C. Fox. "Saker Falco cherrug and Peregrine Falco peregrinus Falcons in Asia: Determining Migration Routes and Trapping Pressure." In Raptors at Risk, ed. R. D. Chancellor and B.-U. Meyburg. Berlin and London: World Working Group on Birds of Prey and Hancock House, 2000.

Fox, N. Understanding the Bird of Prey. Surrey: Hancock House, 1995.

Love, O. P., and D. M. Bird. "Raptors in Urban Landscapes: A Review and Future Concerns." Raptors at Risk, ed. R. D. Chancellor and B.-U. Meyburg. Berlin and London: World Working Group on Birds of Prey and Hancock House, 2000.

Mindell, D. P. Avian Molecular Evolution and Systematics. San Diego: Academic Press, 1997.

Newton, I., and P. Olsen, eds. Birds of Prey. London: Merehurst, 1990.

Olsen, P. Australian Birds of Prey. Sydney and Baltimore: New South Wales Press and Johns Hopkins, 1995.

Sibley, C. G., and J. E. Ahlquist. Phylogeny and Classification of Birds. New Haven: Yale University Press, 1990.

Wink, M., and P. Heidrich. "Molecular Evolution and Ssystematics of the Owls." In Owls: A Guide to Owls of the World, ed. C. Konig, F. Weick, and J.-H. Becking. Sussex: Pica, 1999.

Organizations

The Hawk and Owl Trust. 11 St Marys Close, Abbotskerswell, Newton Abbot, Devon TQ12 5QF United Kingdom. Phone: +44 (0)1626 334864. Fax: +44 (0)1626 334864. E-mail: [email protected] Web site: <http://www.hawkandowltrust.org>

World Center for Birds of Prey, The Peregrine Fund.. 566 West Flying Hawk Lane, Boise, Idaho 83709 USA. Phone: (208) 362-3716. Fax: (208) 362-2376. E-mail: [email protected] Web site: <www.peregrinefund.org>

World Working Group on Birds of Prey and Owls. P.O. Box 52, Towcester, NN12 7ZW United Kingdom. Phone: +44 1 604 862 331. Fax: +44 1 604 862 331. E-mail: [email protected] Web site: <www.raptorsinternational.de>

Penny Olsen, PhD