LONG-EARED OWL

Asio otus

English: Long-eared Owl.
German: Waldohreule.
French: Hibou moyen-duc.

Clasificación/Clasification

Order: Strigiformes.
Family: Strigidae.

Longitud/Length

31-37 cm.

Envergadura/Wingspan

86-98 cm.

Aves relacionadas/Similar species

The Long-eared Owl can be confused with the Short-eared Owl. Both have very similar plumage and size. The Short-eared Owl has intense yellow eyes while the Long-eared Owl has an orange color. On the other hand, the Short-eared Owl has the ends of its wings very dark, almost black and lacks the characteristic “ear” shaped tufts of the Long-eared Owl or the Eurasian Eagle-Owl.

Sexo/Sexing

The inner vane barbs of the secondaries of the adult male Long-eared Owl are white or very close to white. The same whitish tone is also observed in the outer part of the major alula. This feather has a maximum of three transverse bars. The infra-coverts alar feathers are almost pure white, in some specimens without the presence of black dots (buttons) in the primary infra-coverts.

The case of females is different. The inner vane barbs of the secondaries are close to light sienna brown. On the other hand, in the outer vane of the major alula, the same light sienna tone is observed, where this species generally has more than three transverse bars. The infra-coverts do not show the white of the male, being more brownish in the female.

In the case of juvenile specimens, they can be sexed according to the same characteristics and variables as in the case of adults.

Edad/Ageing

It is possible to recognize three different ages:

Juvenile specimen: these individuals have the primary coverts with three or four transverse bars crossing the inner vane. The last bar of the primaries is quite dark and is located very close to the tip of the feather. The last bar of the secondaries is also located at the end of the feather. In these feathers, it is possible to observe up to seven or eight bars. In new specimens that do not yet show any wear in the rectrices, a whitish tip can be observed.

2nd/3rd year specimen: these ages are only detectable in specimens that retain some of the previous generation’s secondaries.

Adult specimen: two or three bars are observed in the primary coverts. The last bar of the primaries is far from the tip. In the secondaries, 3-6 bars can be observed, no more. The rectrices have a gray and fairly speckled tip.

Muda/Moult

Long-eared Owl undergo a complete postnuptial molt that generally ends in the month of October. On the other hand, the postjuvenile molt is partial. This molt includes only body feathers and all the secondary coverts of the wing. Primaries, secondaries, and rectrices begin the process in the first postnuptial molt.

Configuración del plumaje/Plumage configuration

Primaries: 10 per wing.
Secundaries: 13-14 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:

Adult male specimen

1.- Right wing primaries. 2.- Primaries. 3.- Details of the tip of the outer primaries. 4.- Details of the tip of the inner primaries. 5.- Details of the outer vane of the primaries. 6.- Details of the outer vane of the primaries. 7.- Details of the primary calamus area. 8.- Details of the inner vane of P1. 9.- Details of the outer vane of P10. 10.- Details of the tip of P10. 11.- Details of the inner vane of the primaries. 12.- Details of the texture of the beards and barbules of P10. 13.- Secondaries (S1-S6). 14.- Secondaries (S7-S13). 15.- Details of the tip of the secondaries. 16.- Details of the outer vane of the secondaries. 17.- Primaries, secondaries and tertials. 18.- Details of the change of design between primaries and secondaries in the outer vane. 19.- Tertials. 20.- Details of the tertials. 21.- Primaries, secondaries and tertials. 22.- Primaries, secondaries, tertials. Primary coverts and secondary coverts. 23.- Primary coverts. 24.- Secondary coverts. 25.- Primaries, secondaries, tertials. Primary coverts and secondary coverts (G, M, and L). Alulas. 26.- Details of the primary coverts. 27.- Details of the greater coverts. 28.- Details of the greater coverts. 29.- Alulae. 30.- Details of the major alula. 31.- Rectrices. 32.- Rectrices. 33.- Rectrices + uppertail coverts. 34.- Rectrices + undertail coverts. 35.- Details of the rectrices. 36.- Details of the tip of the rectrices (R6-R5). 37.- Details of the texture of the beards and barbules of R6. 38.- Uppertail coverts. 39.- Undertail coverts. 40.- Assembly of feathers known as plumes or “ears”. 41.- Details of the plumes. 42.- Feathers of the plumes. 43.- Primary undercoverts. 44.- Right scapula. 45.- Chest and belly feathers. 46.- Chest and belly feathers.

LONG-EARED OWL

Medidas/Measures

Adult male specimen

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