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The regional population of Tawny Eagle Aquila rapax appears to have decreased at a rate greater than 50% over three generations, satisfying the thresholds for regionally Endangered under criterion A2. In addition, the regional population of less than 1 000 birds is estimated to be undergoing a continuous decline estimated to be greater than 20% in two generations, satisfying the population criterion C1 for regionally Endangered.
The Tawny Eagle is widespread throughout sub-Saharan Africa (Ferguson-Lees and Christie 2001). In southern Africa, it is largely concentrated in protected areas in the north-east and central parts of the region (Simmons 1997), which is confirmed by more recent SABAP2 data. The species is well represented in the IBA network, with Kruger National Park having the highest reporting rates, followed by Kgalagadi Transfrontier Park in Northern Cape and the northern KwaZulu-Natal parks of Ndumo, Mkuze, Hluhluwe-iMfolozi and the iSimangaliso Wetland Park.
Outside of protected areas, the Tawny Eagle has disappeared from large parts of its former range, with reporting rates being substantially lower in SABAP2 than in SABAP1, or with the species now completely absent from certain grid cells. This is consistent with findings by Herremans and Herremans-Tonnoeyr (2000) who found that Tawny Eagle densities in Botswana declined significantly with an increase in distance away from protected land. In particular, the species seems to have disappeared from large parts of the Northern Cape, Free State and Limpopo provinces. A small, sparsely distributed population persists in the grassy Karoo where they have capitalised on power-lines, using pylons as nest structures (Simmons 1997).
There are no clear seasonal movements and the species appears to be sedentary (Steyn 1982). It is considered to be a vagrant to Lesotho (Osborne and Tigar 1990). In different parts of southern Africa, population densities depend on soil types and primary productivity (Hustler and Howells 1986) and on the extent of protected areas (Tarboton and Allan 1984, Brown 1991b), with densities much higher (1.5 pairs/100 km2) within conservation areas than outside (0.3-1 pair/100 km2). The AoO provided by SABAP2 is 98 187 km2 of which 34 146 km2 is protected and 64 031 km2 unprotected. While the EoO estimates have decreased only marginally (9%) between SABAP1 and SABAP2, the AoO has decreased by 58% since SABAP1 (mainly 1987-1993).
The global population was estimated to be at least 100 000 mature individuals (Ferguson-Lees and Christie 2001). Simmons (1997) provided an estimate of 5 000 mature individuals in southern Africa, while Barnes (2000) provided a population estimate of c. 1 600 mature individuals for the region, i.e. South Africa, Lesotho and Swaziland. Simmons et al. (2015) estimated the Namibian population to number c. 1 510 mature individuals. The population in southern Mozambique was estimated at approximately 40 mature individuals (Parker 1999).
Estimation of a regional population is difficult due to wide variation in population densities across the species' range (Simmons 1997). Extrapolation of the published density estimates (Tarboton and Allan 1984, Brown 1991), taking into account the ratio of protected areas to unprotected areas, results in a population of c. 700-1 150 mature individuals in the region. This may be an overestimate given that Murn et al. (2012), based upon a nest survey, provided a breeding population for Kruger National Park (the stronghold for the species in South Africa) of just 172 mature individuals. The regional population is consequently more likely to be c. 500-800 mature individuals. The confidence in this population estimate is low and requires further investigation.
The global population is suspected to be stable in the absence of evidence of any declines or substantial threats (BirdLife International 2014ab). Historical information suggests that the Tawny Eagle has decreased in numbers, as well as range, in the western Karoo in the previous century (Boshoff et al. 1983). Monadjem and Rasmussen (2008) reported that the Tawny Eagle changed from being one of the most frequently observed eagles in Swaziland in the 1970s to being possibly extinct as a breeding species. Outside of the region, Brown (1991) mentioned a decline in Namibia, while Simmons et al. (2015) estimated a greater than 50% decline in the Namibian population over the past three generations or 50 years. The decrease in the regional population would appear to be larger and is almost certainly greater than 60% over the past 50 years. The confidence in this trend estimate is medium.
The Tawny Eagle is one of the most threatened eagles in South Africa (Barnes 2000), with a high sensitivity to land transformation making it largely dependent on conservation areas to survive (Herremans and Herremans-Tonnoeyr 2000). Heavy losses have been documented for large raptors venturing outside of protected areas (Herholdt and Kemp 1997) and the Tawny Eagle is no exception. Owing to its habit of scavenging, Tawny Eagles, together with Bateleurs, suffer the most from deliberate and inadvertent poisoning (Tarboton and Allan 1984). Livestock farmers directly persecute the species because of the perception that the birds catch domestic livestock and poultry, or foul drinking water (Simmons 1997, Anderson 2000). Birds are also inadvertently killed or injured in gin traps set to capture mammalian predators (Anderson 2000).
A decrease in wildlife populations in cattle-farming regions of Namibia resulted in a decrease in Tawny Eagle densities (Brown 1988), although it is unknown if similar decreases have taken place in South Africa. Tawny Eagles, in addition to several other raptor species in South Africa, are susceptible to drowning in sheer-walled reservoirs (Anderson et al. 1999). Birds have been killed by electrocution (Anderson 2000, Barnes 2000) although, conversely, the Tawny Eagle has benefited from using electricity pylons as nesting sites (Anderson 2000). Individuals feeding on road-killed carrion are occasionally killed by motor vehicles (Oatley et al. 1998). Monadjem and Rasmussen (2008) attributed declines of the Swaziland population to habitat loss and nest disturbance.
The Birds of Prey Working Group of the Endangered Wildlife Trust has been active with an awareness and education programme for land-owners and stock farmers in Northern Cape, which has been successful in reducing the number of poisoning incidents (AJ Botha pers. comm.). Two projects run under the auspices of the programme assist with the conservation of Tawny Eagles. The Kalahari Raptor Project focuses on the monitoring and conservation of all raptors in the Kalahari region of South Africa, with a core focus on the Kgalagadi Transfrontier Park and adjacent areas. The Lowveld/Kruger National Park Large Bird Project includes this species in its annual aerial survey of the Kruger National Park and is in the process of obtaining a reliable estimate of the breeding population of this species in the Lowveld. The species is protected in Northern Cape under the Cape Province Nature and Environmental Conservation Ordinance; No. 19 of 1974, while in Swaziland the species is protected under the Swaziland Game Act, No 51 of 1953.
A Population and Habitat Viability Assessment (PHVA) is recommended, as is a Biodiversity Management Plan, culminating in a National Species Recovery Plan. To secure healthy populations of Tawny Eagles, as well as other large, resident eagles, large buffer zones with special management plans are needed around formally protected areas. Vulture restaurants within these buffer zones, which would be utilised by Tawny Eagles, should be promoted. The proactive installation of anti-electrocution, bird-friendly structures should continue. Decreasing the amount of poisoning is crucial to the long-term survival of the Tawny Eagle, although a total ban is impractical as it threatens the agro-chemical industry and is too idealistic to be successful.
* A thorough investigation of the densities of breeding pairs inside and outside of conservation areas throughout the region is needed.
* The minimum area of buffer zones adjacent to protected areas in the region needs to be ascertained. The viability and delineation of these areas need to be investigated.
* The role that habitat transformation has on reduction of the prey base, and consequently on Tawny Eagle densities, needs to be investigated.
* Estimations of immigration and emigration are necessary since the main regional populations are along international boundaries.
* The success of awareness programmes to reduce Tawny Eagle mortalities should be investigated, and if necessary, their design should be improved.