Conserving Martial Eagles
The project aims to understand the factors driving a decrease in the population of Martial Eagles Polemaetus bellicosus in South Africa, with a particular focus on the declines observed within the largest protected area in the country, the Kruger National Park (KNP). This research is important to understand the role that protected areas have in species conservation and to understand specific threats and habitat requirements for the conservation of Martial Eagles.
The project was initiated in response to the decline in reporting rates of Martial Eagles between the Southern African Bird Atlas Projects (SABAP) 1 (1987-1992) and 2 (2007-2012). These surveys suggest a population decrease of up to 65% across South Africa. Declines were also observed inside large protected areas, such as the KNP, which experienced a 54% decline in reporting rate over this time.
We aim to improve our understanding of the threats faced by Martial Eagles and how these threats may drive population decreases even within protected areas, where species are usually expected to be conserved. Our original hypothesis for these declines was that Martial Eagles may be subject to increased mortality outside of protected areas, particularly during immature life stages when inexperienced eagles are likely to range outside protected areas. Contrary to this hypothesis, we have not found evidence for low survival during these early life stages despite ranging widely beyond protected area boundaries. However, GPS tracking of adult birds and nest monitoring have detected two potential factors that may contribute to the observed population decreases: low adult survival and poor breeding productivity. Adult mortalities, including persecution and electrocution, during unexpected wide-ranging movements outside of the KNP, may be contributing to declines. Two factors contribute to the low productivity: a low proportion of pairs attempting to breed and low breeding success. We continue to study breeding performance in the KNP to enable a more comprehensive understanding of the environmental drivers of poor breeding performance, as well as to track eagles to determine the frequency and cause of mortalities.
Activities in 2020
- Of 25 occupied breeding territories there were 13 breeding attempts, which is only the second time since the project started that more than half of the pairs attempted to breed. However, breeding success was low, at 0.30 chicks per attempt.
- Seven nest cameras were installed: four nests were used by Martial Eagle, of which two were successful. Two nests were regularly visited but no eggs were laid, and one nest was used by African Fish Eagles Haliaeetus vocifer, whose eggs were predated by a baboon.
- Two GPS transmitters were deployed on a pair of Martial Eagles, the first time both members of the same pair have been tagged in South Africa.
- CB MSc student Merlyn Nkomo joined us for field experience in Kruger.
- Aerial surveys were carried out with the assistance of the Bateleurs aircraft pilots to look for nests in territories where the known nest is either no longer used or has fallen down. Only around a quarter of the 71 nests are likely to belong to Martial Eagles. All these nests will be checked in 2021.
- Martial Eagles were uplisted to globally Endangered by the IUCN Red List, further highlighting the importance of this research project. The project contributed information to this assessment, including conducting a repeat analysis of the SABAP data.
Impact of the project
Our research indicates that protected areas alone are unlikely to conserve Martial Eagles and that additional conservation measures, such as education programmes and trans-boundary policies should be put in place to ensure the successful conservation of this species.
ABAX Foundation; DSI-NRF CoE grant; Endangered Wildlife Trust; Jock’s Safari Lodge.
Research team 2020
A/Prof. Arjun Amar (FIAO, UCT)
Dr Megan Murgatroyd (HawkWatch International / EWT / FIAO, UCT)
John Davies (Endangered Wildlife Trust)
Dr Gareth Tate (Endangered Wildlife Trust)
Student:Merlyn Nkomo (CB MSc, UCT).