Nombre en español: Agilucho Negro

Nombre en ingles: American Kestrel

Nombre científico: Falco sparverius

Familia: Falconidae

Foto: Mauricio Ossa

El cernícalo americano, halconcito colorado o cuyaya (Falco sparverius) es una especie de ave falconiforme de la familiaFalconidae que habita en gran parte de América, desde Canadá hasta Tierra del Fuego. Es un ave muy utilizada en la cetrería.

Características

Mide de 23 a 27 cm de largo, pesando entre 85 y 140 g. Es una de las pocas especies de rapaces que presentan dimorfismo sexual evidente, incluso en el plumaje juvenil.

Los machos como es usual entre las rapaces diurnas son de menor tamaño que las hembras. En su plumaje adulto tienen las cobertoras de las alas de un color grisáceo claro con puntos negros, y las primarias negras con puntos blancos. La cola es rojiza con una franja negra en el extremo seguida por puntas blancas.

La hembra es de mayor tamaño que los machos, en su plumaje adulto tiene tanto las cobertoras del ala como la cola de un tono rojizo barrado en negro.

Alimentación

Se alimenta de insectos, roedores, otras aves, anfibios y reptiles pequeños que generalmente caza volando desde una atalaya natural o artificial. Ocasionalmente emplea la técnica de atacar a sus presas desde una posición estática que mantiene volando (Cernirse; Origen de su nombre común en castellano)

Reproducción

Al igual que los demás representantes del género Falco no construye su propio nido. Deposita sus huevos en cavidades de árboles o nidos abandonados de otras especies de aves, frecuentemente utiliza oquedades creadas por pájaros carpinteros, tanto en árboles como en termiteros. También utiliza cajas nido artificiales si están disponibles en su territorio.

La hembra deposita de uno a cinco huevos moteados en el nido, el macho le aporta alimento y continua haciéndolo al nacer los pichones, cuando los pichones aumentan su tamaño la hembra también caza y aporta presas al nido.

Historia natural

Frecuentemente es observado solitario o en parejas, no forman grupos sociales aunque pueden agruparse durante la migración

Subespecies

Se conocen 17 subespecies de Falco sparverius:

Falco sparverius sparverius – Norteamérica (de Alaska a Terranova, y al sur hasta el oeste de México).
Falco sparverius paulus – costas del sur de Estados Unidos hasta Florida.
Falco sparverius peninsularis – oeste de México (sur de Baja California, Sonora y Sinaloa).
Falco sparverius tropicalis – del sur de México hasta el norte de Honduras.
Falco sparverius nicaraguensis – sabanas de Honduras y Nicaragua.
Falco sparverius caribaearum – Indias Occidentales (de Puerto Rico a Grenada).
Falco sparverius brevipennis – Antillas Holandesas (Aruba, Curazao y Bonaire).
Falco sparverius dominicensis – La Española.
Falco sparverius sparverioides – Bahamas, Cuba e Isla de la Juventud.
Falco sparverius ochraceus – montañas del este de Colombia y noroeste de Venezuela.
Falco sparverius caucae – montañas del oeste de Colombia.
Falco sparverius isabellinus – de Venezuela al norte de Brasil.
Falco sparverius aequatorialis – norte subtropical de Ecuador.
Falco sparverius peruvianus – sudoeste subtropical de Ecuador, Perú y norte de Chile.
Falco sparverius fernandensis – Isla Robinson Crusoe (Archipiélago Juan Fernández, Chile).
Falco sparverius cinnamonimus – del sudeste de Perú, Chile, Uruguay y Argentina, hasta el archipiélago de Tierra del Fuego.
Falco sparverius cearae – mesetas del noreste de Brasil al este de Bolivia.

American kestrel

The American kestrel (Falco sparverius) is the smallest and most common falcon in North America. It has about a two to one range in size over subspecies and sex, varying in size from about the weight of a blue jay to a mourning dove. It also ranges to South America, and is a well established species that has evolved seventeen subspecies adapted to different environments and habitats throughout the Americas. It exhibits sexual dimorphism in size (females being moderately larger) and plumage, although both sexes have a rufous back with noticeable barring. Its plumage is colorful and attractive, and juveniles are similar in plumage to adults.

The American kestrel usually hunts in energy conserving fashion by perching and scanning the ground for prey to ambush, though it also hunts from the air. It sometimes hovers in the air with rapid wing beats while homing in on prey. Its diet typically consists of grasshoppers and other insects, lizards, mice, and small birds (e.g. sparrows). This broad diet has contributed to its wide success as a species. It nests in cavities in trees, cliffs, buildings, and other structures. The female lays three to seven eggs, which both sexes help to incubate.

Its breeding range extends from central and western Alaska across northern Canada to Nova Scotia, and south throughout North America, into central Mexico and the Caribbean. It is a local breeder in Central America and is widely distributed throughout South America. Most birds breeding in Canada and the northern United States migrate south in the winter. It is an occasional vagrant to western Europe.

Based on appearance and behavior it was for many years considered a member of the primarily European and African kestrel clade within the genus falco, but recent DNA analysis shows the American kestrel to actually be genetically more closely related to the larger American falcons such as the Aplomado falcon, the Peregrine falcon, and Prairie falcon. Though the species has not been renamed as a result of these genetic analyses, it is not actually a kestrel in the phylogenetic sense. Instead, a process of convergent evolution to fit a similar small prey niche in the ecosystem as the true kestrels has left it with similar physical characteristics and hunting methods.

The American kestrel is a common bird used in falconry, especially by beginners. Though not as strong a flyer as many other larger falcons, proper training and weight control by the falconer allows many American kestrels to become effective hunters of birds in the size range of sparrows and starlings, with occasional success against birds up to approximately twice their own weight.

Description

Under traditional classification, the American kestrel is the smallest raptor in America.The American kestrel is sexually dimorphic, although there is some overlap in plumage coloration between the sexes. The bird ranges from 22 to 31 cm (8.7 to 12.2 in) in length with a wingspan of 51–61 cm (20–24 in). The female kestrel is larger than the male, though less so than larger falcons, being typically about 10% to 15% larger within a subspecies. The more northern subspecies tend to larger sizes, with a large northern female being about twice the size of a small southern male. The male typically weighs 80–143 g (2.8–5.0 oz), and the female 86–165 g (3.0–5.8 oz). In standard measurements, the wing bone is 16–21 cm (6.3–8.3 in) long, the tail is 11–15 cm (4.3–5.9 in) and the tarsus is 3.2–4 cm (1.3–1.6 in).

Physically, American kestrels are leaner and less muscular than larger falcons. The pectoral flight muscles of the American kestrel make up only about 12% of its body weight, as compared to about 20% for the strongest flying falcons such as the peregrine. The wings are moderately long, fairly narrow, and taper to a point. Their less muscular body type is adapted to energy conserving ambush hunting, rather than spending large amounts of energy consuming time on the wing and getting into long tail-chases of bird prey. For their size, they have strong talons and beaks, and can swiftly dispatch prey. Their lean build and energy conserving strategy allows a lower daily food intake than if they were more strongly muscled, yet with enough strength to commonly take bird prey as large as themselves, and occasionally larger. The success of this body style and hunting strategy is reflected in the high success of the species in densely populating a large range throughout the Americas. The flight of the American kestrel is not so dramatic and swift as more muscular falcons such as Merlins and peregrines, but their efficient adaptation to a broader diet of more available smaller prey, and need for less food per day, has resulted in there being many more of them.

In contrast to many other raptor species, the sexes differ more in plumage than in size. Males have blue-grey wings with black spots and white undersides with black barring. The back is rufous, with barring on the lower half. The belly and flanks are white with black spotting. The tail is also rufous, with a white or rufous tip and a black subterminal band. The back and wings of the female American kestrel are rufous with dark brown barring. The undersides of the females are creamy to buff with heavy brown streaking. The tail is noticeably different from the male’s, being rufous in color with numerous narrow dark black bars. Juveniles exhibit coloration patterns similar to the adults’. In both sexes, the head is white with a bluish-grey top. There are also two narrow, vertical black facial markings on each side of the head, while other falcons have one. Two black spots (ocelli) can be found on each side of the white or orangish nape. The function of these spots is debated, but the most commonly accepted theory is that they act as «false eyes», and help to protect the bird from potential attackers.

Vocalizations

The American kestrel has three basic vocalizations – the «klee» or «killy», the «whine», and the «chitter.»The «klee» is usually delivered as a rapid series – klee, klee, klee, klee when the kestrel is upset or excited. This call is used in a wide variety of situations and is heard from both sexes, but the larger females typically have lower-pitched voices than the males. The «whine» call is primarily associated with feeding, but is also uttered during copulation. The «chitter» is used in activities that involve interaction between male and female birds, including courtship feeding, copulation, and the feeding of nestlings.Nestlings can produce calls similar to those of adults at 16 days old.

Taxonomy

Until the sixth edition of the AOU Checklist of North American Birds was published by the American Ornithologists’ Union in 1983, the most commonly used name for the American kestrel was the sparrow hawk or sparrowhawk. This was due to a mistaken connection with the Eurasian sparrowhawk in the genusAccipiter. The sixth edition of the AOU Checklist corrected this, officially renaming the bird American kestrel. Several other colloquial names for the kestrel are also in use, including grasshopper hawk, due to its diet, and killy hawk, due to its distinct call.

As noted in the introduction, DNA analysis shows the American kestrel to actually be genetically more closely related to the larger American falcons than to the true kestrels. However, based on its physical similarity to the kestrels and the established nature of the name American kestrel, there has been little impetus to change its name. This could change in the future if continued genetic research more precisely determines the evolutionary history of the American kestrel within the genus falco. The entire genus is actually a set of species so closely related that most or all can be hybridized by artificial insemination. Significant natural hybridization of species has occurred in the past during the evolution of this closely related set of species, such that precise evolutionary genetic analysis as to which species are more basal to other species or to the genus as a whole is difficult to render.

The American kestrel’s scientific name, Falco sparverius, was given by Carl Linnaeus in his 18th century work Systema Naturae. The genus refers to the falcate, or hooked, shape of the beak, and the specific name means «pertaining to a sparrow», referring to the bird’s small size and hunting of sparrows as a typical prey.

Seventeen subspecies of the American kestrel are recognized, generally based upon plumage, size, and vocalizations:

F. s. sparverius, described by Linnaeus in 1758, is the nominate subspecies. It is found in most of the United States, Canada, and Mexico.
F. s. paulus, described by Howe and King in 1902, is found in the Southeast United States, from Louisiana to Florida.
F. s. peninsularis, described by Mearns in 1892, is found in southern Baja California.
F. s. tropicalis, described by Griscom in 1930, is found from southern Mexico to northern Honduras.
F. s. nicaraguensis, described by Howell in 1965, is found in Honduras and Nicaragua.
F. s. sparveroides, described by Vigors in 1827, is found in Cuba and the Isle of Youth, and southern to central Bahamas.
F. s. dominicensis, described by Gmelin in 1788, is found in Hispaniola and Jamaica.
F. s. caribaearum, described by Gmelin in 1788, is found in Puerto Rico through the Lesser Antilles to Grenada.
F. s. brevipennis, described by Berlepsch in 1892, is found in the Netherlands Antilles.
F. s. isabellinus, described by Swainson in 1837, is found from Venezuela to northern Brazil.
F. s. ochraceus, described by Cory in 1915, is found in eastern Colombia and northwest Venezuela.
F. s. caucae, described by Chapman in 1915, is found in western Colombia.
F. s. aequatorialis, described by Mearns in 1892, is found in northern Ecuador.
F. s. peruvianus, described by Cory in 1915, is found in southwest Ecuador, Peru, and northern Chile.
F. s. fernandensis, described by Chapman in 1915, is found on the Juan Fernández Islands off Chile.
F. s. cinnamominu, described by Swainson in 1837, is found in Peru, Chile, and Argentina.
F. s. cearae, described by Cory in 1915, is found from northeast Brazil south to eastern Bolivia.