The Magnificent Queen of the Mediterranean Forest

By Jose Luis Gallego, environmental communicator (@ecogallego)

The silhouette of the Spanish imperial eagle, one of the planet’s most threatened birds of prey, is once again flying high over territories from which it had disappeared years ago. The extraordinary efforts of scientists, conservationists, and governmental administrations, along with the invaluable collaboration of rural communities, has paid off: this beautiful bird of prey, on the verge of extinction in the late 1970s, is still among us.    

This diurnal raptor, which scientists classify under the Latin name Aquila adalberti, is an indigenous species of the Iberian peninsula; in other words, it is only found in Spain and Portugal. It is a large bird with a strong compact build and all the attributes of a powerful hunter. Around 80 centimetres long, the Spanish imperial eagle can reach a wingspan of over two metres, that is to say the distance from wingtip to wingtip when the bird is in flight. Males weigh about 2.5 kilos, whereas the much larger females can weigh up to 4 kilos. 

The colour of their feathers changes with age. Adults sport elegant dark brown plumage with a cream-coloured nape and distinctive white-shouldered epaulettes. By contrast, juveniles have mottled colouring, ranging from cream to reddish brown-grey, that evens out as they mature. 

A Spanish imperial eagle, photo by: Ana Mínguez. 

Their silhouette in flight is impressive. A female eagle flying over her territory is absolutely unmistakable. She can be identified by her long, narrow wings with distinctive flight feathers at the tips that resemble long, spread-out fingers, and her short rectangular tail, which, in the case of a juvenile, opens up like a fan. One could almost mistake her for a golden eagle were it not for the territory in question. Territory, after all, determines a species, and these nesting and hunting grounds belong to the Spanish imperial eagle. 

In contrast to its golden kin, the Spanish imperial eagle isn’t fond of mountain peaks and is found exclusively in forests, showing a clear preference for wooded flatland areas with an abundance of Mediterranean scrubs and scattered meadows. The raptor seeks out clusters of holm and cork oaks surrounded by meadowlands, pinewoods in low mountain ranges, and valleys with open oak groves and the occasional riverbank woodland. 

The imperial eagle is a resident bird of prey, but outside of its nesting period, it may travel long distances in search of areas with a more abundant food supply, preferably rabbits. The mating period begins in late December and concludes in February. By the end of February, the female will have already laid her eggs, usually two. The eaglets stay in the nest from April until June. Fledging takes place throughout the summer and, if everything goes well, by October the young eagles seek their own territories, far from that of their parents, who remain mates for life. 

Spanish imperial eagle, photo by: Ana Mínguez. 

The Spanish imperial eagle’s main food source is the mountain rabbit, something the raptor has in common with other Mediterranean woodland predators such as the Iberian lynx, who shares the eagle’s territory.  The little lagomorph represents more than half of an eagle’s daily catch, which means its presence largely determines that of the raptor as well. 

In addition to rabbits, Spanish imperial eagles complete their diet with myriad vertebrates of all sizes. This includes birds like pigeons and turtledoves, partridges, water birds, crows, and other raptors like kites and kestrels. Amphibians and reptiles also make the list, as do mammals all along the food chain, from small rodents to hares, foxes, badgers, mountains cats, even roe deer, deer fawn, and boarlets. On rare occasions, the eagle may even prey on wolf cubs or lynx kits. During periods of scarcity, Spanish imperial eagles may feed on carrion.

The distribution of the raptor’s territory is very specific and limited to the southwestern portion of the Iberian peninsula, essentially to the Community of Madrid, Castilla-La Mancha, Castilla y León, Andalucia, and Extremadura. From here the eagle’s territory extends ever so slightly into the central region of eastern Portugal where it maintains a small nesting ground.  

As mentioned at the beginning of this article, the Spanish imperial eagle returned from the brink of extinction. At one point, fewer than one hundred pairs remained, its population decimated by the indiscriminate use of pesticides, habitat destruction, overhead electrical cables, and poaching. Fortunately, the species recovered, and at this time, the Spanish imperial eagle population consists of more than 500 breeding pairs. 

Much of this success is due to the coordinated efforts of scientists, conservationists, and governmental administrations, especially the EU funding provided through Life, a nature conservation programme.  The Spanish imperial eagle is included in Spain’s Libro Rojo de las Aves de España, similar to the ICUN Red List of Threatened Species, where the raptor is still listed as endangered and enjoys strict legal protection.