Eastern Imperial Eagle

(Aquila heliaca)

The Eastern Imperial Eagle was previously thought to be a subspecies of the Spanish Imperial Eagle, but recent research has shown that the two are in fact distinct species.

The Eastern Imperial Eagle population in Europe has suffered intensely over past centuries, due to direct persecution by humans, and as a result became extinct (or almost extinct) in many areas.

However, in recent decades, there has been a small positive development for the population of Eastern Imperial Eagles in Europe, due to sustained conservation efforts. 

As part of this positive trend, Eastern Imperial Eagles have returned to breed in Austria with a few pairs, after having been absent from this part of their range for a long time.

This positive development shows that there is hope for our raptors if we continue to work hard for their protection.

Eastern Imperial Eagle facts

While similar to the Golden Eagle, the Eastern Imperial Eagle has smaller talons, and weighs less, reflecting the fact that it hunts smaller prey on average.

Eastern Imperial Eagle size

In terms of wingspan, the Eastern Imperial Eagle is very similar to the Golden Eagle, although it has a shorter tail and a lower body weight.

• Eastern Imperial Eagle wingspan: 200-220 cm (female), 180-200 cm (male)
• Length: 73-83 cm
• Weight: 3,150-4,550 g (female), 2,450-2,750 g (male)

The lower weight of Eastern Imperial Eagles when compared to Golden Eagles is due to the fact that they have a less powerful build, and hence lower muscular strength, which is an indicator that they hunt smaller prey. 

Appearance

Overall, the Eastern Imperial Eagle is a large eagle, though not quite as big as a Golden Eagle or White-tailed Eagle. 

Sexual dimorphism

As is the case with most other European birds of prey, male Eastern Imperial Eagles are smaller than females, although there is an overlap in size between the sexes.

Lifespan

With a maximum age of 44 years recorded in captivity, the Eastern Imperial Eagle is one of the European raptors with the longest lifespan. In the wild, the maximum recorded lifespan is 26 years.

Scientific name and taxonomy

The scientific name of the Eastern Imperial Eagle is Aquila heliaca. There are no subspecies of the Eastern Imperial Eagle, it is closely related to both the Spanish Imperial Eagle, and the Steppe Eagle. 

Eastern Imperial Eagle distribution

The Eastern Imperial Eagle breeds in eastern Europe, with the westernmost part of its range in Austria and the Czech Republic. Its range extends eastwards from eastern Europe to central Asia and northern India.

Eastern Imperial Eagle habitat

The Eastern Imperial Eagle prefers open landscapes, such as steppes and semi-arid zones. In addition to open habitat, it also requires trees for nesting, though this need can be fulfilled by a small group of trees, or even a single tree. Outside of the breeding season it also frequents marshland and bodies of water, where it hunts waterfowl.

Eastern Imperial Eagle population size

With an estimated population of just over 1,000 breeding pairs, the Eastern Imperial Eagle is one of the rarest raptor species in Europe. Most of these pairs are found in the European part of Russia. The global population of these birds of prey is estimated to be less than 20,000 pairs.

Eastern Imperial Eagle behavior

Similar to other eagle species that hunt in open landscapes, the Eastern Imperial Eagle likes to sit on the ground and wait there for rodents to emerge from their burrows. In addition to small mammals, it also takes birds and carrion.

Feeding and diet

The main food source of Eastern Imperial Eagles are small mammals, which can vary by region. In Austria, for example, the main prey are young hares, while in other regions they are susliks or marmots.

Outside of the breeding season it also hunts waterfowl and is often found feeding on carrion. Overall, the Eastern Imperial Eagle is extremely adaptable, and able to take advantage of many different prey species.

Breeding

The Eastern Imperial Eagle builds its nest in trees, and the female lays 2-3 eggs, which are incubated for up to 44 days. In contrast to other eagle species and large raptors, there is less cainism among the chicks after they hatch, and as a result this eagle often raises 2 or even 3 chicks successfully.

Migration

The Eastern Imperial Eagle is a partial migratory bird, with most of the European population wintering in the Middle East, but some also in Greece and Turkey. In addition to this, many of the adult birds stay close to their breeding range even during the winter months. 

Eastern Imperial Eagle conservation status

As one of the rarest raptors in Europe, the Eastern Imperial Eagle is classified as “Vulnerable” by BirdLife International. The key reason for this is that many local populations of Eastern Imperial Eagles consist of a handful of pairs, and there are large gaps between different populations. This disjointed distribution pattern makes each population more vulnerable to adverse events.

Threats

The main threat to Eastern Imperial Eagles is illegal poisoning, which still occurs, although less often than in the past. In addition to poisoning, destruction of habitat (and especially suitable trees for nesting) is another serious problem that needs to be addressed. Finally, electrocution on power poles is another issue that can and should be eliminated effectively.

Additional resources:

• Lesser Spotted Eagle population size
• Diet and feeding behavior of Greater Spotted Eagle
• Bonelli’s Eagle size