BOOTED EAGLE · Hieraaetus pennatus
L: 42-50 cm. E: 110-135 cm. Wing:♂340-395 mm,♀375-435 mm. Weight:♂510-770 g.,♀840-1.150 g. Longevity: < 15 years old.
Coordinators: Alex Ollé & Joan Goy
It is basically a trans-Saharan migrant, arriving in Europe to nest between the end of March and April, leaving for Africa between the end of August and October.
Some autumns are marked by a variable number of individuals migrating northwards, due to the bad weather conditions encountered in the Strait of Gibraltar. In this way, they perform a loop migration, moving to Africa via Italy. In the years when this phenomenon occurs with greater intensity, the number of wintering Booted Egrets is much higher on the Spanish Mediterranean coast.
It does a complete moult every year.
Second plumage (transitional): At the end of May or June of 2cy they begin the moult, which is retained in their autumn migration in September or October. At this time it has moulted the 5-7 innermost primaries, and already in Africa, it finishes its moult in the winter quarters. Some specimens may retain some juvenile primaries until the spring of 3cy.
It seems that wintering birds in Spain do not moult during these dates, so that in the spring of 3cy they show a very late moult extension compared to wintering birds in Africa.
Adult plumage: Adults moult very similarly to the 2cy, starting in Europe and ending in Africa.
Although females are slightly larger, it is very difficult to differentiate the sexes.
Two distinct forms or morphs. The proportion of the light morph is lower the further east in Europe, there being a certain relationship with the climate. In Spain, the light morph is present in between 60 and 90 % of the individuals, depending on the area. Those determined as intermediate, belong to light specimens of the dark form.
Egyptian Vulture, Black Kite.
BOSCH, J. 2019. Clinal polymorphism variation in the Booted Eagle Hieraaetus pennatus: the influence of climate during the breeding season. Bird Study 66.
BOSCH, J., MESTRE, J., BAIGES, C., MARTÍNEZ, J.E, CALVO, J.F. & JIMÉNEZ, M.V. 2019. Colour plumage polymorphism in the Booted Eagle: inheritance pattern and temporal stability of the morph frequencies. Journal of Zoology
OLLÉ, A. & TRABALON, F. 2019. Aves rapaces de Europa. Omega.