This emblematic eagle of the Iberian Peninsula is gradually reclaiming its foothold across Spain. Endemic to this region, it does not occur naturally anywhere else in the world. After facing near extinction, dedicated remediation efforts have helped stabilize and gradually expand its presence in natural habitats, though the journey remains fragile.
By the 1960s the Iberian imperial eagle had reached critical endangerment, with only about 30 breeding pairs remaining, all within Spain. Recovery began in the 1980s, when conservation initiatives fostered approximately five new breeding pairs each year up to 1994. By 2011 the global population stood at 324 pairs, and by 2015 the count exceeded five hundred.
Yet threats persisted. In 2018 the breeding tally showed a dip to 407 pairs, underscoring the variability of its recovery. The main dangers today include power lines, illegal hunting, and the loss of preferred habitats.
Spanish imperial eagle, sometimes referred to as the Iberian adalbert, is a notable bird because Spain and Portugal are the only European regions to host an endemic eagle species. Its most striking feature is its flawless plumage. Wingspan ranges from 190 to 220 centimeters, and the bird presents very dark brown plumage with white shoulder patches and golden hints on the back of the head and neck. It is a large bird of prey, ranking as the second largest eagle in Spain after the golden eagle and placing among the top five raptors on the continent.
Juvenile plumage differs dramatically from adults, which often makes identification challenging for researchers. Juveniles show a brown to reddish tint that shifts to straw yellow in the second year, gradually darkening until the adult coloration appears around five years of age when sexual maturity is reached.
Two in one home
Imperial eagles are monogamous, and once they settle in a territory, they tend to stay put. Consequently, nests are large and conspicuous. They typically build nests on relatively low trees such as cork oak, pine, or eucalyptus, and the nests accumulate mass over the years.
The pair works as a team to construct the nest. Both adults carry nesting materials, while the female completes the interior. Nest site selection favors inaccessible areas away from infrastructure and human settlements.
They lay four to five eggs, each about 130 grams, incubated for roughly 43 days between March and July. Up to three eaglets may hatch, but often only the oldest survives periods of limited food. The young remain under parental supervision for about four months and fledge after roughly 65 to 78 days.
In the wild, the imperial eagle can live around 20 years, with lifespans reaching up to 41 in captivity. Its preferred habitats span pine forests in mountainous regions to coastal dunes and marshes, though flat and low-relief areas are favored, and large rabbit populations have regained numbers in the most secluded zones when threats are lowest.
Continuing dangers, especially power infrastructure
Primary threats include habitat loss, human intrusion, collisions with power lines, and illegal poisoning. In recent years, significant conservation efforts have yielded encouraging results. Measures to reduce power-line mortality, minimize supplemental feeding, repair nests, relocate critical sites, and limit disturbance during the breeding season have all contributed to protecting nests. Ongoing monitoring accompanies every nest to safeguard the birds.
Despite progress, removing eagles from danger remains challenging. Habitat loss through deforestation, agricultural expansion, and the expansion of irrigation schemes continues to threaten populations. Electric shocks from lines account for a substantial portion of mortality today. Reduced prey availability and changing hunting patterns also pose challenges to the species’ ecological role in the Mediterranean food web.
Despite gains, the Iberian imperial eagle remains listed as vulnerable by the international conservation community. Rabbit populations, a major food source, face pressures from disease and environmental changes, while other prey includes various birds, small mammals, reptiles, and occasional larger carnivores. Ongoing research and adaptive management are essential for maintaining momentum in conservation efforts. [Citation: SEO/BirdLife]