The Crowned Eagle

Natural history of the Crowned Eagle

The Crowned Eagle (Stephanoaetus coronatus) is a large, powerful and attractively coloured eagle of forested and hilly landscapes of sub-Saharan Africa. The female eagle is larger and more powerful than the male, weighs over 3,5 kg and with a wingspan of 1,5 – 1,8 m. Adults have dark backs and heavily barred breasts often with a tinge of rufous. The under-wing coverts are also rufous with black longitudinal bars. The long tail has characteristic broad, dark bars.

The species has undergone a decline throughout its range in Africa and is now classified as regionally “Vulnerable.” The aim of the Crowned Eagle Monitoring Project is to describe and monitor the Crowned Eagle population along the Drakensberg Escarpment in Mpumalanga Province, South Africa. This project has now been ongoing for 18 years and has focussed particularly on the location and monitoring of Crowned Eagle nests. 

A forest specialist

The Crowned Eagle is a forest specialist. It  occurs where there are fragments of indigenous temperate forest on the escarpment or dense woodland in mountainous granitic areas. Its short round wings and long tail allow it to be highly manoeuvrable in dense vegetation allowing it to follow prey through thickets and branches. The heavily barred chest also provides excellent camouflage in the dappled light of forests allowing it to ambush prey. 

Crowned Eagles nest in large trees, usually along drainage lines. The spacing between the nests, in suitable habitat, is relatively constant averaging 10 km, suggesting that the population could be saturated in suitable habitat.

Nests are repeatedly used

Most nests are repeatedly used and can become very large structures. It is not uncommon for a nest to be used for over twenty years.  If a nest does collapse due to a severe storm , in some cases a new nest will be constructed in the same fork. Nest trees have specific features, often being the largest straight trunked tree in the centre of the territory.

Most of the nests are in indigenous trees although there are a few in large exotic eucalyptus and pine trees.

Over the past seventeen years, a total of 62 Crowned Eagle nests have been located around Mbombela. Breeding takes place every alternate year unless there is some disruption. Chick and fledgling survival appears to be high.

Threats

The biggest threats facing the Crowned Eagles are habitat change and persecution. Although the nests being placed  in inaccessible ravines and drainage lines are relatively secure, the habitat for their prey is being rapidly changed to orchards.  Afforestation along the escarpment does not seem to have adversely affected the Crowned Eagle population.

Active nests are the best indicator of the health of a raptor population.

EagleCam2 – a camera at the Crowned Eagles’ nest

The purpose of placing a camera (EagleCam2) at the nest is to document the eagles’ behaviour at the nest. It is an important part of the Crowned Eagle Monitoring Project with the aim to record prey species selection, reproduction behaviour, and the growth and behaviour of the chick prior to fledging. The advantage of the technology being used to collect images is that there will be no disturbance at the nest.