BONELLI’S EAGLE

Aquila fasciata

English: Bonelli’s Eagle.
German: Habichtsadler.
French: Aigle de Bonelli.

Clasificación/Clasification

Order: Accipitriformes.
Family: Accipitridae.

Longitud/Length

60-70 cm.

Envergadura/Wingspan

150-170 cm.

Aves relacionadas/Similar species

The Bonelli’s Eagle is easily distinguishable by its white and spotted chest with dark tears. Its feathered legs, size, and overall feather design make it well distinguishable.

Sexo/Sexing

Both the male and female have very similar plumage. Generally, the male may have a whiter plumage with finer spots on the chest and belly than the female in adulthood. Size may only be a variable to consider in extreme cases.

Edad/Ageing

It is possible to recognize 3 different ages:

Juvenile specimen: the back is washed in dark cream tones, often with a light speckled pattern. The head plumage is the same tone, this time a little lighter. The belly feathers are ocher. All flight feathers (both wing and tail) are of the first generation. On the other hand, the underwing coverts are chestnut. The secondaries are gray-brown with a regular pattern. These feathers lack the dark subterminal band characteristic of adult plumage. The rectrices are in line with the plumage, light brown, with 8 or 9 dark transverse bars that also lack the dark subterminal band.

2nd-3rd year specimens: in a way, these individuals present a back quite similar to the adult’s, tones close to the juvenile plumage, but large dark tears typical of adult plumage. The belly will be mixed between yellowish and white tones. The flight feathers and rectrices show a visible molt limit between retained juvenile feathers and adult type feathers. 3rd-year individuals present a very fierce wear on the retained feathers of the juvenile generation.

Adult specimens: the back is dark gray-brown, sometimes speckled with white. The crown and ear feathers are the darkest areas of the head. Both the chest and belly are white with speckled (tear-shaped) dark marks. The underwing coverts are dark gray. The secondaries are dark gray with a slightly blurred pattern. In this age, the clear broad subterminal band appears. In the case of observing a molt limit, all feathers will be of adult type. The rectrices are gray with fine patterning and a wide dark subterminal band.

Muda/Moult

Bonelli’s Eagle perform a complete post-nuptial molt. In this process, not all flight feathers change each year. This molt usually begins in July or August and is completed in January. On the other hand, the post-juvenile molt will begin in the 2nd year of life. In this process, some flight feathers are not replaced and even sometimes some rectrices, which will be changed in the 3rd year.

Configuración del plumaje/Plumage configuration

Primaries: 10 per wing.
Secundaries: 14-16 per wing.
Rectrices: 12.

Observaciones/Remarks

Link: http://blascozumeta.com/

La obtención de este material ha sido posible gracias al permiso necesario de la Junta de Andalucía.

AUTORIZACIÓN DE LA DIRECTORA GENERAL DE MEDIO NATURAL, BIODIVERSIDAD Y ESPACIOS PROTEGIDOS DE LA CONSEJERÍA DE AGRICULTURA, GANADERÍA, PESCA Y DESARROLLO SOSTENIBLE DE LA JUNTA DE ANDALUCÍA, PARA LA CESIÓN DE MUESTRAS BIOLÓGICAS DE ESPECIES DE FAUNA (ARTÍCULO 9 DE LA LEY 8/2003, DE 28 DE OCTUBRE, DE LA FLORA Y LA FAUNA SILVESTRES).

Medidas/Measures

Biometría/Biometrics

3rd year male specimen

1.- Right wing primaries. 2.- Primaries. 3.- Tips of primaries details. 4.- Details of P10. 5.- Details of tips of P1, P2, and P3. 6.- Details of tips of primaries. 7.- Details of primaries. 8.- Details of inner vane primaries. 9.- Details of outer vane primaries. 10.- Details of outer vane primaries. 11.- Details of outer vane primaries. 12.- Details of inner vane P5. 13.- Secondaries (S1-S7). 14.- Secondaries (S8-S15). 15-. Right wing secondaries and tertials. 16.- Inner vane details of S2, S3, and S4. 17.- Difference between new generation feather, adult plumage (left), and juvenile plumage (right). 18.- Subterminal band details of S1. 19.- Inner vane details of S1. 20.- Outer vane details of secondaries. 21.- Details of secondaries with great wear at the tips. 22.- Primaries, secondaries, and tertials. 23.- Primaries, secondaries, and tertials. 24.- tertials. 25.- Primaries, secondaries, tertials. Primary coverts and greater coverts. 26.- Primaries, secondaries, tertials. Greater and median coverts + primary covert. 27.- Primaries, secondaries, tertials. Primary coverts and secondary covert (greater, median, and lesser). Alulas. 28.- Details of secondary covert. 29.- Secondary covert. 30.- Details of greater coverts. 31.- Visible wear between primaries. Left: new generation. Right: juvenile plumage. 32.- Alulas. 33.- Primary coverts. 34.- Greater coverts. 35.- Median coverts. 36.- Rectrices. 37.- Rectrices. 38.- Details of rectrices. 39.- Tips of rectrices details. 40.- Rectrices + uppertail coverts. 41.- Details of uppertail coverts. 42.- Rectrices + undertail coverts. 43.- Rectrices + details of undertail coverts. 44.- Primary infra-covert. 45.- Secondary infra-covert. 46.- Axillary feathers. 47.- Right scapula. 48.- Underbelly feathers. 49.- Chest feathers. 50.- Chest feathers assembly. 51.- Assembly of crown feathers. 52.- Crown and head feathers. 53.- Assembly of leg feather. 54.- Right leg feathers. 55.- Assembly of back feathers. 56.- Back feathers.

BONELLI’S EAGLE

Medidas/Measures

3rd year male specimen

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