EURASIAN EAGLE-OWL

Bubo bubo

English: Eurasian Eagle Owl.
German: Uhu.
French: Grand-duc d’Europe.

Clasificación/Clasification

Order: Strigiformes.
Family: Strigidae.

Longitud/Length

57-75 cm.

Envergadura/Wingspan

140-188 cm.

Aves relacionadas/Similar species

It is not possible to confuse the Eurasian Eagle Owl with any other Iberian species.

Sexo/Sexing

Both male and female have very similar plumage, so it is not a character to consider for sexing.

Edad/Ageing

It is possible to recognize 5 different ages:

Juvenile specimen: they have the feathers of the wing and the rectrices of the same generation, that is, without molting limits. The primary coverts have three to five dark bars, where the last one is located near the tip. The primaries have a rounded tip, and also with the last dark bar near the tip. In the central secondaries, the last dark bar is also observed near the tip. The tertials have the bars in the form of an arrow touching both ends of the feather. In the central rectrices (R1) the bars touch both sides of the feather. In R6 the last dark bar is observed near the tip.

2nd year / 3rd year specimen: the flight feathers are from the previous year. Only some primaries or secondaries have changed, so there is a great contrast with the more worn neighboring feathers. As a rule, in the rectrices only the central pair are of a new generation.

3rd year / 4th year specimen: by this age they have changed the 2 or 3 outermost primaries with their corresponding primary coverts and most of the secondaries. In these specimens, a generation of juvenile feathers and two generations of adult-type feathers are observed.

4th year / 5th year specimen: it is common to see some primaries still retained. On occasions, some secondaries may also be seen.

Adult specimen: these individuals present several generations of feathers, all of them adult type. The primary coverts usually have indistinct transverse bars, the last one far from the tip. The primaries have a square tip and their last dark bar far from the tip. The central secondaries with the last dark bar far from the tip. The tertials have incomplete transverse bars that do not reach both ends of the feather. The central rectrices (R1) have some of the incomplete bars that do not reach both sides of the feather. R6 has the last dark bar far from the tip.

Muda/Moult

The Eurasian Eagle Owl undergo a partial post-nuptial molt in which they annually change part of the body feathers and wing coverts. The flight feathers take several years to be fully renewed (they molt between 5 and 9 each year). This process usually takes place between June and October. On the other hand, the post-juvenile molt lasts until four years old. The body feathers and part of the wing coverts are changed in the first year, the primary coverts, flight feathers, and rectrices are retained. In the 2nd year of life, they molt the tertials, some infracoverts, and the central pair of rectrices. During the 3rd year molt, 2 to 3 primaries with their corresponding coverts are changed. Already in the 4th year they finish changing all the secondaries and the juvenile primaries with their corresponding coverts, of which some primaries may still be retained. This post-juvenile molt process usually starts in May and ends in October.

Configuración del plumaje/Plumage configuration

Primaries: 10 per wing.
Secundaries: 14-18 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

Adult specimen:
Beak tip to pupil center:
Tarsus:

4th year specimen

1.- Left wing primaries. 2.- Primaries. 3.- Outer vane details of the primaries. 4.- Details of the calamus of the primaries. 5.- Details of the outer and inner vanes of the P8. 6.- Details of the tip of the inner primaries. 7.- Details of the tip of the outer primaries. 8.- Details of the outer vane of the P8. 9.- Details of the outer vane of the P10. 10.- Details of the outer vane of the P8. 11.- Details of the P10. 12.- Outer vane details of the primaries. 13.- Details of the outer vane of the P8. 14.- Secondaries (S18-S10). 15.- Secondaries (S9-S1). 16.- Left wing secondaries and tertials. 17.- Outer vane details of the secondaries. 18.- Details of the tip of the secondaries. 19.- Details of the S7. 20.- Details of the S9. 21.- Details of the S12. 22.- Primaries, secondaries and tertials of the left wing. 23.- Primaries, secondaries, and tertials. Primary coverts and secondary coverts. 24.- Details of the tertials. 25.- Primaries, secondaries, and tertials. Primary coverts. Greater and median coverts. 26.- Details of the primary coverts. 27.- Details of the primary coverts. 28.- Details of the greater coverts. 29.- Primaries, secondaries, and tertials. Primary coverts and secondary coverts (greater, median, and lesser). Alulas. 30.- Details of the secondary coverts. 31.- Details of the median coverts. 32.- Details of the lesser coverts. 33.- Primary coverts. 34.- Details of the primary coverts. 35.- Secondary coverts. 36.- Alulas. 37.- Details of the large alula. 38.- Rectrices. 39.- Rectrices. 40.- Rectrices + uppertail coverts. 41.- Details of the outer vane of the rectrices. 42.- Details of the tip of the rectrices. 43.- Details of the R2. 44.- Uppertail coverts. 45.- Uppertail coverts. 46.- Rectrices + undertail coverts. 47.- Undertail coverts. 48.- Primary infra-coverts. 49.- Secondary infra-coverts. 50.- Assembly of the left scapula. 51.- Left scapula. 52.- Feathers of the left tarsus. 53.– Chest feathers. 54.- Details of the chest feathers. 55.- Chest feathers. 56.- Left flank. 57.- Belly feathers. 58.- Sensory feathers surrounding the beak. 59.- Face and ear feathers. 60.- Assembly of the feathers. 61.- Assembly of the feathers. 62.- Feathers.

EURASIAN EAGLE-OWL

Medidas/Measures

4th year specimen

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