The eagle owl ( Bubo bubo ) is one of the hunters that come out of hiding at twilight in search of food.
Many people are surprised to learn the dimensions of this giant of the night, and that is that the owl can reach 75 centimeters in height with a wingspan – width that the bird has with its wings extended – of 1.80 meters. Despite its imposing size, the owl is able to fly in absolute silence thanks to its feathers, which minimize the impact of the air. This ability, together with its extraordinary auditory and visual abilities, makes the animal an effective hunter. It should be noted that what are normally thought to be the owl’s “ears” are actually two groups of feathers that cover the ear and simply curl up .
The eagle owl is a super predator as it preys on other predators. To learn about the diet of an animal as elusive as the owl, which on rare and privileged occasions can be caught red-handed when approaching a prey, the researchers resort to indirect observation methods. In the case of many carnivores, the simplest thing is to study their pellets , balls formed by remains of skin, bones and hair that the animals have not been able to digest and regurgitate. Identifying these “leftovers” from the feast provides a lot of information about the predators’ eating habits.
The analysis of owl pellets reveals that their diet is very varied, and it hunts practically everything that is available : foxes, marten, raptors and other birds … however, in the Iberian Peninsula its most common prey are rabbits and rats , surely due to its abundance.
Independence comes little by little
The first reproduction of the eagle owl can occur in the first year of age, and the first spawns in the Iberian Peninsula are recorded in December. The females are in charge of the incubation, which lasts just over 30 days .
Chickens spend some time in the nest under parental care. Before beginning the period of dispersal, in which the young owls settle in other territories, these “adolescents” begin little by little their forays into the unknown. Its area of exploration increases progressively but, yes, it always includes the nest . The definitive time to start dispersal is around 5 or 6 months of age, although, as with humans, some chickens linger longer and may take more than a year to “become independent.” The dispersal distances are also highly variable, between 1 and more than 30 kilometers.
It is also curious that although the distance between siblings increases over time, young people of different sexes tend to remain closer together, and this bond does not always dissolve during the first phases of dispersal.
Although the eagle owl is the most emblematic, it is not the only nocturnal bird of prey on the Iberian Peninsula. Its relatives include other smaller birds such as scops owl (Otus stops), long- eared owl (Asio otus ), tawny owl (Strix aluco ), barn owl ( Tyto alba ) and owl ( Athene noctua ).
(Source: Virtual Encyclopedia of Spanish Vertebrates, National Museum of Natural Sciences CSIC)
