Species characteristics

The lesser spotted eagle, Aquila pomarina (Clanga pomarina), is the smallest eagle occurring in Poland, with a wingspan of 145-168 cm and body length of 61-66 cm. Females are slightly larger than males. Body weight is about 1.6 kg.   

A characteristic feature of the bird’s silhouette during flight is the wings bent downwards in an arch. Males and females have identical colouring – their plumage is mainly in different shades of brown. Quills are dark brown, whereas the plumage of the trunk, wing converts and crown is tan. Talons and base of the bill are bright yellow. First-year birds are significantly darker than their parents and have distinct white spots on the edges of the wing converts and overtail converts.

The lesser spotted eagle is a migratory species. It spends the winter in central and southern Africa, starting its autumn migration in mid-September and returning to the breeding grounds at the beginning of April. Adult birds and young birds migrate to the winter quarters separately.

The lesser spotted eagle is a monogamous species, reaching sexual maturity at the age of 4-5 years (rarely 3).

The female most often lays 2 eggs and they hatch with an interval of 3-4 days.  Usually only one young lesser spotted eagle is raised, as the older nestling is aggressive towards the younger one and eventually kills it or contributes to its death from starvation (the phenomenon of cainism).

 
Nesting habitat

The lesser spotted eagle resides in multi-storey forests, mainly deciduous and mixed, over 70 years old. It builds its nest on different tree species. In the Lublin region the majority of the nests occupied by lesser spotted eagles are built on pine, oak, alder and birch. At the beginning the nest is quite small but can eventually reach considerable size because the birds may use it for several breeding seasons in a row. Lesser spotted eagles often occupy the nests built by buzzards or other carnivorous birds. The abundance of feeding grounds has a strong influence on the presence of the birds and the size of their nesting grounds. These birds willingly hunt in the mosaic of the agricultural landscape, rich in boundary strips, patches of idle land and wetlands. The size of the nesting territory occupied by a pair of lesser spotted eagles is most often larger than 1000 ha. To efficiently protect this species it is necessary to preserve not only the habitats where it builds nests but also the feeding grounds.

Diet

The lesser spotted eagle primarily hunts for small mammals, mainly rodents. Amphibians and small birds serve as a dietary enrichment. The lesser spotted eagle uses three main hunting techniques: swooping and diving, waiting in a hide for a prey and sometimes collecting food walking along the ground in meadows and fields. 

Distribution

The lesser spotted eagle’s distribution range is restricted to eastern and southern Europe and the Near East. The distribution of this species in Poland is irregular and mainly concentrated in north-eastern and south-eastern Poland. The bird also occurs in Western and Central Pomerania, whereas single dispersed stands are also found in Central Poland, Wielkopolska and the Opole region. The size of the national population is estimated at 2300-2700 individuals.

Conservation status

In Poland the lesser spotted eagle is under strict protection. To minimise the human pressure on the animals, protection zones are established around the nests. The lesser spotted eagle was placed in the Polish Red Data Book of Animals as a vulnerable species and in Attachment 1 to the Birds Directive. The national population is stable in terms of abundance and range.

Threats

The most serious threats to the lesser spotted eagle are:

• disappearing feeding grounds,
• uncontrolled building and infrastructure development,
• increasing anthropopression causing disturbance of birds during the breeding season,
• persecution of birds during migration