The population of Africa’s largest eagle species is in freefall in South Africa, and may be soaring towards extinction, according to a new University of Cape Town (UCT) study based on changes in sighting rates over the last twenty years.
Martial Eagle sightings have dropped by as much as 60% since the late 1980s, in stark contrast to human population growth across their shared natural habitat, said the study published this week in the scientific journal Bird Conservation International. Although the exact reasons for the decline remain unclear, researchers say their findings point to an urgent need to better understand the threats to this iconic bird.
Worryingly, the study also highlighted a marked decline in Martial Eagle sightings within protected areas, including in the world famous Kruger National Park and the Kalahari Gemsbok National Park. However, declines of the species in protected areas were not as severe as elsewhere, suggesting that these areas could act to buffer the factors leading to declines.
Martial Eagles mainly prey on large birds and reptiles, and small and medium sized mammals, but are strong enough to prey on small antelopes. They typically nest in high treetops.
Their plight made international headlines last year when Mozambican hunters killed an adult bird that had featured in a British documentary starring well-known wildlife presenter Steve Backshall. At the time the bird was being tracked via a GPS satellite tag.
The research was conducted by Dr Arjun Amar and PhD student Daniël Cloete from UCT’s FitzPatrick Institute of African Ornithology, using two Southern African Bird Atlas Project (SABAP) surveys carried out twenty years apart. Their previous research showed that comparing these surveys provided an accurate way of measuring changes in the population size of this eagle species.
Martial Eagle total population figures are still relatively inexact, but their conservation status was uplisted in 2013 from Near Threatened to Vulnerable – which means they are recognised to be globally threatened. The study published this week provides the most accurate assessment for the decline of the species in any African country and was only possible due to an army of volunteer bird watchers that contribute their sightings to the SABAP database.
The study found significant declines in three provinces; these were Kwa-Zulu Natal, Mpumalanga and Limpopo. Changes differed across the biomes (distinct regions with similar geography and climate), with the species faring worst in the Grassland, Savannah, Indian Ocean Coastal Belt and the Nama Karoo biomes. However, there was better news in the Fynbos biome of the Western and Eastern Cape, where reporting rates remained more stable over the last 20 years.
“Despite having full legal protection in South Africa, this species is known to be targeted and killed by farmers who blame the species for predation of their livestock, or may be accidentally killed by poison left to kill other predator species,” the authors noted.
Another major threat for the Martial Eagles, may be electricity infrastructure such as power lines, particularly among juveniles which have a wider territorial range.
Dr Amar, the lead author of the study said “this analysis was only possible thanks to the efforts of many hundreds of dedicated volunteer bird watchers who contribute their records to the SABAP survey database”. Dr Amar added “we have now quantified the decline of the species in South Africa, but that is the only the first step, we now need urgent research to better understand the factors which are responsible for causing this iconic species to be lost from our countryside, so that these factors can be better controlled”.
Dr Arjun Amar is a Senior Lecturer at the FitzPatrick Institute of African Ornithology and the Department of Biological Sciences, University of Cape Town