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Current Research Programmes

Conserving Martial Eagles

The Martial Eagle 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 that have been 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 population declines 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 this species and how these threats may drive population declines 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 into areas with increased human pressures.

Contrary to this hypothesis, data collected since 2013 did not find evidence for low survival during these early life stages despite ranging widely beyond protected area boundaries. However, through GPS tracking of adult birds and nest monitoring, two potential factors that may be contributing to the observed population declines have been detected: 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. The poor breeding productivity comes in two forms: both a lower than average number of pairs making a breeding attempt and low success of those pairs which do try. To better understand the latter, our primary aim going forward is to install cameras at a number of nests. We will also continue to investigate the eagles’ movements in the KNP using GPS tracking. In 2018, in a partnership with the Endangered Wildlife Trust (EWT), we will investigate the breeding and movement ecology of the substantial population of Martial Eagles that nest on electricity pylons in the Karoo. This will help us to understand national population declines and the requirements of the species.

Activities in 2017

  • Megan Murgatroyd monitored the breeding activity of 33 pairs of Martial Eagles in the KNP, via three nest surveys (early, mid, late season).
  • The 2017 early season surveys showed a promising breeding attempt rate with 15 attempts (close to 50% of the population, expected for a biannual breeder). However, mid-season surveys showed poor success with high failure rates and the late season monitoring revealed another two nest failures. One of which was the loss of a large chick that would have been close to fledging. Feather remains were found on and below the nest.  Nearly half of the 2017 breeding attempts failed for unknown reasons.
  • We continued to track several adult and juvenile eagles. An additional adult eagle was tagged in the KNP and its nest was located via the GPS tracking data.
  • SANParks authorised a research addendum allowing the collection of prey remains below nests. We have started to collect remains for a diet analysis, which might give an insight into why some territories do better than others.

Highlights:

  • Rowen van Eeden graduated with his PhD in June 2017.
  • Rowen’s paper on adult habitat preferences and ranging behaviours was published in PLoS ONE (van Eeden et al. 2007. PLoS ONE 12(3): e0173956).
  • We also published key research that quantified the overall decline of the species across South Africa and within the KNP (Amar & Cloete in press, Bird Conservation International). This paper was widely reported on in the South Africa media.

Impact of the project

Our research indicates that protected areas alone are unlikely to conserve this species and that additional conservation measures, such as education programmes, or trans-boundary policy should be put in place to ensure the successful conservation of this species.

Key co-sponsors

ABAX Foundation; DST-NRF CoE grant; Endangered Wildlife Trust.

Research team

Dr Arjun Amar (FIAO, UCT)
Dr Megan Murgatroyd (FIAO, UCT)
Dr Gareth Tate (FIAO, UCT, Endangered Wildlife Trust)
Dr Rowen van Eeden (FIAO, UCT)