Imperial eagle (Aquila heliaca)

Imperial Eagle is a large, dark-colored species of eagle. Adult individuals have dark brown plumage with pale yellow-cream colored crowns and napes. Shoulder feathers are white. The tail is gray with a black band at the tip. The beak and legs are yellow, with a black tip on the beak. Juveniles are lighter brown and display white spotting on the wing coverts.

Body length ranges from 72 to 83 cm. Wingspan varies between 185 and 205 cm in males and 200 to 220 cm in females. Body weight is between 2.4 and 2.7 kg in males and 3.1 to 4.5 kg in females. In the wild they can live up to approximately 26 years and over 40 years in captivity.

The Imperial Eagle is generally solitary but can be observed in loose groups of more than ten individuals during migration. It soars using thermal air currents and glides while traveling. During hunting it can make rapid movements. It typically flies with calm and broad wingbeats but may execute sudden dives to capture prey.

^{Kaşif Şahgaga (Kaynak:} AA⁾

This species inhabits steppe-forest transition zones and can nest in open areas such as plains and agricultural lands near wetlands and steppes. Its upward shift in altitude is considered a consequence of habitat loss and human pressure.

Nests are typically built on tall trees at heights of 10 to 20 meters above ground. The nest diameter is approximately 1.2 to 1.5 meters and its depth is 60 to 70 cm. Females usually lay two eggs per year. After the incubation period, chicks hatch and become capable of flight within about 60 days. Due to food competition, survival rates are typically limited to only one chick.

As a carnivorous species, the Imperial Eagle feeds primarily on small mammals such as field voles, rats, hamsters and rabbits, birds including ducks, pigeons and crows, reptiles such as snakes and turtles, some insects and carrion. It captures prey on the ground using its talons and carries it away.

The breeding range of the Imperial Eagle extends across a wide geographic area between Central and Eastern Europe and Central Asia. It regularly breeds in countries such as Austria, Hungary, Slovakia and Russia as well as Kazakhstan outside Türkiye. During migration it is also observed in regions such as North Africa, South Asia and the Middle East.

The population in Türkiye is estimated to consist of between 42 and 180 breeding pairs. Detailed studies in the Thrace region indicate a population of approximately 30 to 50 pairs.

Major threats to the Imperial Eagle include agricultural pesticides, habitat loss, power transmission lines, illegal logging, vehicle collisions, decline of prey species and illegal hunting. High-voltage power lines and poisoning are particularly significant causes of individual mortality. Additionally, the placement of wind energy plants along the flight corridors of eagles can lead to collision-related deaths.

^{Fotoğraf: İbrahim Yozoğlu (Kaynak:} AA⁾

The Imperial Eagle typically begins breeding at the age of four. Pairs remain together for life; if one partner dies, the surviving bird may find a new mate the following year. Pairs usually establish long-lived nests that are maintained and reused over many years. Dry branches and large tree fragments are used in nest construction. Nest diameter is approximately 120 to 150 cm and depth is 60 to 70 cm.

Egg-laying generally occurs in spring. Females typically lay two eggs per year, occasionally three or four. Both parents participate in incubation, which lasts an average of 43 days. Usually both eggs hatch but due to food competition, only one chick typically survives. This behavior is linked to the species’ characteristic “sibling killing.” The earlier-hatching and stronger chick dominates the other and secures its survival.

Chicks acquire flight capability approximately 60 days after hatching. However, they continue to be fed by their parents for about two weeks after leaving the nest. During this period they develop their flying and hunting skills.

The Imperial Eagle (Aquila heliaca) is a fully carnivorous raptor. It usually hunts alone, though occasionally hunts with its mate. It typically captures prey on the ground and is less agile than other raptors when pursuing birds in flight.

While hunting, it often glides over open terrain and attacks with a sudden dive upon spotting suitable prey. It also perches on tall trees at forest edges to survey the surroundings and swoops down on prey when the opportunity arises. Its vision is highly developed, enabling it to easily detect prey from high altitudes.

After capturing prey, it kills it with its powerful curved talons, carries it and usually brings it back to the nest for consumption. During the process of capturing, carrying and killing prey, it actively uses both its talons and beak.

The diet of the Imperial Eagle varies according to geographic region and season. It includes small and medium-sized mammals, birds, reptiles, carrion and occasionally insects. Commonly consumed mammals include the suslik (Spermophilus sp.), hedgehog (Erinaceus concolor), European hare (Lepus europaeus), blind mole rat (Nannospalax leucodon) and field mouse (Apodemus sp.). Among birds, gulls, pigeons, ducks and partridges are important dietary components. Reptiles such as turtles and snakes are also consumed.

The Imperial Eagle (Aquila heliaca) is ecologically specialized to steppe-forest transition zones and prefers extensive, semi-open mosaic habitats. Its habitats generally include wooded steppes, gallery forests, steppes and isolated tall trees in agricultural areas. These habitats provide suitable conditions for both nesting and hunting.

Nests are typically built on large trees at heights of 10 to 25 meters above ground. When suitable trees are unavailable, some individuals have been recorded nesting on low shrubs or human-made structures. Nests in the same area are reused over many years and grow larger over time.

In Thrace, studies have found that Imperial Eagles most frequently build their nests on Quercus pubescens (downy oak), Quercus cerris (Turkey oak), Quercus frainetto (Hungarian oak), Populus nigra (black poplar) and Salix species (willows). These trees are often found singly within agricultural land and provide eagles with unobstructed views of their surroundings.

The structure of vegetation surrounding the nest and hunting areas is important. Imperial Eagles prefer open agricultural areas containing tree clusters or individual trees. They rarely nest in dense, closed-canopy forests. This preference is related to ease of hunting and selection of habitats with high prey density.

The global distribution of the Imperial Eagle extends from Austria to Mongolia, covering the central and southern regions of Eurasia. Breeding populations are concentrated primarily in Kazakhstan, Russia, Hungary, Slovakia and Türkiye. During migration it is also observed in regions such as North Africa, the Indian subcontinent and Southeast Asian countries.

The total number of breeding pairs in Europe ranges between 850 and 1300. The two largest populations are in Russia (900–1000 pairs) and Kazakhstan (750–800 pairs).

Estimates of the population size in Türkiye vary. Previous studies indicated 35–70 pairs, while more recent assessments suggest a range of 42 to 180 pairs.

Field studies in Thrace have revealed a population of approximately 30 to 50 pairs.

As a migratory species, the Imperial Eagle is observed during winter across a wide geographic range from northern Africa to Kenya, India and southern China. In Europe it is primarily known as a summer visitor.