Nombre en español: Azor Bicolor
Nombre en inglés: Bicolored Hawk
Nombre científico: Accipiter bicolor
Familia: Accipitridae
El azor bicolor o gavilán bicolor (Accipiter bicolor) es una especie de ave accipitriforme de la familia Accipitridae ampliamente extendido por la Región Neotropical, encontrándose desde el sur de México hasta Panamá y por toda Sudamérica, a excepción de el desierto costero peruano y Chile.
El Azor Bicolor es un ave escondediza y dificil de ver, aunque es común y su distribución probablemente abarca todo el País. Es un depredador especializado en aves. Accipiter deriva del latín y significa agarrar. Su epíteto bicolor también deriva del latín y significa de dos colores haciendo referencia a su doble coloración.
Tamaño y Forma
El macho mide 36cm de largo y pesa 260g, la hembra mide 46cm y pesa 400g. Sus alas son más bien cortas y redondeadas, cola bastante larga con la punta redondeada, el iris es anaranjado y la cera y las patas son amarillas. Los adultos presentan corona negra, lados de la cabeza, nuca, dorso y rabadilla color gris plomo azulado siendo más oscuro en alas y cola; esta última con tres barras estrechas y ápice blanco sucio. Por debajo son gris pálido, aunque algunos son gris oscuro con muslos rojizos. Los inmaduros son de color negruzco encima, generalmente con collar difuso blanquecino o ante; partes inferiores blancas o crema salpicadas de marrón, tibias frecuentemente más oscuras o moteadas de rufo.
Especies Similares
Adultos se confunden sólo con individuos pálidos de la subespecia ventralis del Azor Cordillerano.
Diferencias Regionales
En Colombia encontramos la subespecie nominal bicolor.
Subespecies
Se conocen cuatro subespecies de Accipiter bicolor :
- Accipiter bicolor fidens – tierras bajas del sur de México (Oaxaca, Veracruz y península del Yucatán).
- Accipiter bicolor bicolor – del sudeste de México (Pen. Yucatán) a las Guayanas, Brasil y noroeste de Perú.
- Accipiter bicolor pileatus – de Brasil al sur del Río Amazonas al noreste de Argentina.
- Accipiter bicolor guttifer – de Bolivia a Paraguay, sudoeste de Brasil (Mato Grosso) y norte de Argentina.
Distribución
Hasta 2000m sobre el nivel del mar. Probablemente se encuentra en todo el país. Conocido del noroccidente del Chocó, en el nororiente de la región de Santa Marta y en el extremo norte de la cordillera Central, sur de Tolima, norte de Huila y en la base oriental de los Andes. También se encuentra desde el oriente de México hasta Tierra del Fuego.
(Vieillot, 1817)
Habitat
En general no está asociado a ningún hábitat en particular. No obstante se ha reportado en sotobosques y dosel de bosques vírgenes o intervenidos, bordes de bosque y crecimiento secundario alto.
Alimentación
Se alimenta principalmente de aves de tamaño pequeño. En menor proporción también se alimenta de pequeños mamíferos y lagartijas. Puede seguir tropas de monos para atrapar insectos. Espera la presa silenciosamente entre un escondite denso y se lanza sobre esta con rapidez. Puede volar velozmente entre perchas en el dosel y efectuar un rápido reconocimiento, para así perseguir de cerca a cualquier presa que haya podido espantar. Puede dirigirse a un árbol en fructificación lleno de aves y lanzarse en pos de una víctima.
Reproducción
Su nido consiste en una copa pequeña (30-40 cm de ancho) hecha de palitos y forrada con hojas o musgo. Lo coloca en lo alto o en la parte media de un árbol en el bosque, al final de una rama o entre una masa de epífitas. Huevo de color blanco, con rayas rojizas desteñidas. Se reproducen entre finales de la época seca y comienzos de la lluviosa. El tamaño de la nidada es de 1 a 3 huevos de color blanco o blanco azulado. Las hembras se encargan de la mayor parte de la incubación y la protección del nido, y los machos proveen comida a la hembra y los polluelos. El tiempo de incubación es de alrededor de 34 días y los jovenes abandonan el nido entre el dia 30 y 36.
Comportamiento
Es un ave escondidiza, díficil de ver. Sin embargo es bastante activa en la persecucion de sus presas, principalmente aves. Caza al acecho y se lanza en pos de las presas desde perchas en ramas internas, o vuela silencioso y a baja altura sobre el sotobosque. Se le ha visto atacando grupos de monos ardilla (Saimiri sp.) y monos tamarines (Saguinus sp.).
Taxonomía
Se necesita más estudios para esclarecer las relaciones taxonómicas de esta especie con A. chilensis, la cual difiere en su ecología, especialmente en sus preferencias de hábitat. Además forma una superespecie con A. cooperii y A. gundlachi. Se recomienda realizar una estudio molecular de las poblaciones de Suramérica. Se reconocen cuatro subespecies, de las cuales sólo A. b. bicolor está presente en Colombia.
Bicolored hawk
The bicolored hawk (Accipiter bicolor) is a species of bird of prey in the family Accipitridae. It is found in forest, woodland, second growth, plantations, and wooded savanna in southeastern Mexico, Central America, and northern and central South America (as far south as northern Argentina). Though generally uncommon, it is the most common species of Accipiter in most of its range, but it does not occur at altitudes above 2,700 metres (8,900 ft) such as the highest parts of the Andes.
Description
At 34–45 centimetres (13–18 in) in length and 200–450 grams (7.1–15.9 oz) in weight, it is significantly smaller than the northern goshawk of Eurasia and North America, and somewhat smaller than the Cooper’s hawk of North America, but among the largest Accipiter hawks in Central and South America (only the rare grey-bellied hawk is larger). As in other Accipiter hawks, the female is far larger than the male. Adults are grey above with darker wings and crown, and a banded tail. The underparts typically vary from dark grey to very pale grey, but the southern subspecies can sometimes be rufescent below. The thighs are always pure rufous (not always easily seen), and the underwing coverts are white in the northern subspecies and rufous in the southern. Juveniles are very variable. They can be white, buff or rufous below, and sometimes with dark streaks. Their upperparts are browner than in adults, and the thighs are sometimes paler.
Taxonomy
The bicolored hawk is a species in the genus Accipiter and is included in the family Accipitridae. Three subspecies are currently recognized. The bicolored hawk is also closely related to the Cooper’s hawk (A. cooperii) and the Gundlach’s hawk (A. gundlachi); these three form a superspecies.[4] Until recently, the Chilean hawk (A. chilensis) from the colder, southernmost South America was treated as a race of A. bicolor but due to its differences in habitat preferences and plumages from the bicolored hawk, A. chilensis is now considered a full species.
Four subspecies of A. bicolor are acknowledged. These are:
- A. b. bicolor, which is found in Southeastern Mexico and south through northern South America. Adults have a black crown, slate upper parts and a blackish tail that displays two or three pale bars. The primaries are obscurely barred.
- A. b. fidens, which occurs in Eastern and Southern Mexico. It is morphologically similar to A. b. bicolor, but is larger in size and darker in color.
- A. b. pileatus, living in Brazil. Adults are similar to A. b. bicolor, but are much paler and have a pearl-grey collar. Under-wing coverts and thighs are rufous.
- A. b. guttifer; located in South Bolivia and northern Argentina. The underparts of the adult are grey or extensively salmon rufous with large white spots and bars.
Habitat and distribution
The bicolored hawk is widespread but uncommonly observed. Its range extends from Mexico to west Ecuador, the Guianas to Colombia, south to east Peru, through Amazonian Brazil to Paraguay, north-northwestern Argentina, Bolivia and to Chile. It mainly resides in forest, along forest edges and in clearings in tropical and locally subtropical zones, although its habitat is none too specialized. It may also reside in rain forest, drier, thinned forest, and palm savanna with gallery forest.
Forest disturbance and fragmentation negatively affect the habitat and quantity of the bicolored hawk, which is most abundant in primary undisturbed forest or riparian forest. There are fewer hawks in disturbed habitats such as forests that have been logged, and even fewer in those fragmented habitats that provide greater than 66% forest cover. These hawks are rarely present in forests that provide less than 66% forest cover.
Behaviour
The bicolored hawk is difficult to detect due to its shyness and inconspicuousness. Because of this behaviour, the bicolored hawk may be more common than it seems.
Vocalisations
Its vocalisations are mainly subdued and unnoticeable. Males have been heard to give a soft, clear whistle and females can emit a loud «cac cac cac» when around the nest and young. A barking «kra-kra-kra-kr-kr-kr-ka» may also be heard from both sexes. During incubation, males give a sharp «kek» vocalisation upon arrival to the nest with food, to which the female replies with a nasal «wreh«.
Diet
These hawks capture prey in a stealthy manner by flying through dense vegetation to ambush unsuspecting prey. They may also capture prey through aerial pursuit after inconspicuously sitting and watching their target. At times, the bicoloured hawk may hunt in pairs. Most commonly, it feeds on smaller birds such as thrushes and small doves but has also been known to consume small mammals including bats and reptiles. Several instances where the hawks attack groups of squirrel monkeys or tamarins have been witnessed. In addition, these hawks may follow groups of monkeys in order to feed on the insects that are exposed by the monkeys.
Reproduction
Bicolored hawks breed in forest areas, choosing to build nests on tree branches and occasionally hanging vines. The nest is built in cooperation between the male and female and is constructed from dried sticks and leaves. Each breeding pair will normally build a new nest at the beginning of each breeding year. Copulation occurs after breeding activities such as feeding and nest building have been completed. Egg laying takes place approximately five weeks after copulation and the dull white eggs measure an average of 47.1 mm × 36.5 mm; clutches average 1–3 eggs. The eggs are brooded for about three weeks by the female while the male forages for food. Bicolored hawk chicks are categorized as semi-altricial; the eyes are open at hatching but the chicks are not immediately mobile and are fed by the parents. The young fledge around 30–36 days after hatching and the fledgling period spans nearly seven weeks, during which the young will return to the nest frequently for food until they become independent.
Fuentes: Wikipedia/eBird/xeno-canto/WikiAves
