Rationale
(Changed due to Genuine (recent))
The regional population of Verreaux's Eagle Aquila verreauxii qualifies as regionally Vulnerable under the population-size criterion (less than 10 000 mature individuals with a continuing decline estimated to be greater than 10% in three generations). In addition, the species approaches the population-trend criterion for regionally Vulnerable (an observed, estimated, inferred or suspected population size reduction of 30% over three generations where the reduction or its causes may not have ceased or may not be understood or may not be reversible).
Distribution
Verreaux's Eagle has a wide distribution throughout Africa, stretching from Eritrea and Ethiopia in the north, southward to South Africa (Ferguson-Lees and Christie 2001). Within the region, the species is distributed across five different biomes: Fynbos, Grassland, Savannah, Nama-Karoo and Succulent Karoo. Within these biomes, it is mainly restricted to mountainous terrain (Davies and Allan 1997) because of its hunting and breeding biology. The distribution is closely linked to the presence of Rock Hyrax Procavia capensis (Gargett and Mundy 1990). For example, in Giant's Castle Nature Reserve, KwaZulu-Natal, the amount of suitable habitat for Rock Hyrax was limited, and Verreaux's Eagles had larger home ranges (Brown 1988). Surprisingly, it is scarce to absent in apparently suitable habitat in much of Lesotho and the former Transkei (Davies and Allan 1997). The species is restricted to the Highveld of Swaziland, with nests recorded in Mlilwane Wildlife Sanctuary and suspected in Malolotja National Park (Monadjem et al. 2003).
At the time of writing, the species had been recorded from 998 pentads during SABAP2. A comparison of the EoO between SABAP1 and SABAP2 shows minimal change (-2%), but a decline of 42% in AoO. The species is still well represented in the IBA network throughout the region.
Population
The global population has not been quantified, but is thought to number in the tens of thousands (BirdLife International 2014). Few historical and no current regional population estimates exist. Tarboton and Allan (1984) estimated the population in north-eastern South Africa to be 500 mature individuals. Davies (1994) provides an estimate of 2 000 mature individuals for the former Cape Province. In Swaziland, Parker (1994) estimated there to be 10 mature individuals, with Monadjem and Rasmussen (2008) providing a slightly lower estimate of eight birds. Reported densities in the region range from a low of one pair/65 km2 in the Drakensberg (Brown 1988) to one pair/24 km2 in the Karoo (Davies and Ferguson 2000). Allan (1988) calculated average home ranges of 35 km2 for birds in the Magaliesberg, based on 13 pairs spaced on average 9.5 km apart, while figures calculated for suitable habitat in other areas of the former Transvaal averaged 7-13 km between pairs (Tarboton and Allan 1984).
Outside of the region, a maximum of one pair/10 km2 was recorded in the Matobos, Zimbabwe (Gargett and Mundy 1990), an area of optimal habitat. An average density of one pair/41 km2 was used to extrapolate a regional population of 3 505 mature individuals, based on the reported AoO of 71 856 km2. This estimate is possibly an underestimate for two reasons. The density estimate may be higher than reported, with the average influenced by Brown's study in the Drakensberg (Brown 1988). In addition, large areas of Northern Cape and western portions of North West Province, where the species is up to seven times more abundant than other raptors (Boshoff et al. 1983), have not been adequately atlased. The regional population is therefore estimated to be 3 500-3 750 mature individuals. Confidence in this estimate is low and this figure requires verification.
Population trend
The global population trend is thought to be stable in the absence of declines or substantial threats (BirdLife International 2014). Within the region, Verreaux's Eagle has apparently undergone a reduction of 42% in AoO since 1993, as well as a drop in reporting rates in KwaZulu-Natal, Eastern Cape, Free State, Gauteng, Limpopo and Mpumalanga. This suggests that the species has undergone a decline in population between the two atlas reporting periods. However, the relationship between AoO as calculated for SABAP1 and SABAP2 data, and populations of large, sparsely distributed birds, has not been verified. The regional population is suspected to be undergoing a decline, although the rate is unknown and requires further investigation. While the exact rate of decline is not known it is thought to be greater than 10% over three generations. Confidence in this estimate is low.
Threats
The primary threat faced by the species within the region is pressure from stock farmers (Davies 1994). Direct persecution by farmers is usually in retaliation to these eagles catching domestic livestock and poultry, or fouling drinking water (Anderson 2000). Ironically, the beneficial role that a pair of Verreaux's Eagles play on a farm, in terms of controlling hyrax numbers and distribution, outweighs the cost of occasional lamb predation by a factor of 155 times (Davies and Ferguson 2000). Fortunately, the species' low reliance on carrion, in contrast to the habits of Tawny Eagle Aquila rapax and Bateleur Terathopius ecaudatus, reduces the risk from poisoning events (Davies and Allan 1997).
Incidents of Verreauxs' Eagle being caught and killed/maimed in gin traps in Northern Cape have been reported (Anderson 2000). The depletion of the primary prey species, Rock Hyrax, through hunting is likely to have a negative impact on breeding success (Monadjem et al. 2003) and has been identified by several authors as a reason for localised declines (Osborne and Tigar 1990, Chiweshe 2007).
Anderson at al. (1999) reported that Verreaux's Eagle is one of the four raptors most likely to drown in reservoirs. Urbanisation is a threat, particularly if it results in a decrease in the prey base. Allan (1984), in his study of Verreaux's Eagle in the Magaliesberg, reported that most breeding failures were human-induced. The species is somewhat susceptible to collisions with and resultant electrocution from power-lines and related infrastructure. Development of wind farms, especially in mountainous areas, poses a future threat to this species, which may prove to be highly significant.
Conservation
Underway
Two projects, run under the auspices of Endangered Wildlife Trust's Birds of Prey Working Group, assist with conservation of Verreaux's Eagle. The Western Cape Black Eagle Project focuses on aspects of the biology of Verreaux's Eagles in Table Mountain National Park, the eastern False Bay Mountains and the western edge of Clanwilliam, the Nuweveldberge of Karoo National Park and the Cederberg. The Kalahari Raptor Project facilitates the monitoring and conservation of all raptors in the Kalahari region of South Africa, with a focus on Kgalagadi TFCA and adjacent areas. A separate project in Western Cape, the Black Eagle Project, operates under the auspices of the Cape Leopard Trust and Animal Demography Unit. The species is listed as regionally Near Threatened in Namibia (Simmons et al. 2015) and regionally Vulnerable in Swaziland (Monadjem et al. 2003). It is protected in Northern Cape under the Cape Province Nature and Environmental Conservation Ordinance; No. 19 of 1974, as well as the Swaziland Game Act, No. 51 of 1953 (Monadjem et al. 2003).
Proposed
The main threat to Verreaux's Eagle is persecution by stock farmers. The success of awareness programmes should be investigated, and if necessary, improvements made. Proactive installation of anti-electrocution, bird-friendly power-line structures should continue. Simple measures to prevent drownings in reservoirs include attaching a floating log to the side of the reservoir, placing a cover over reservoirs, and keeping reservoirs full (Anderson et al. 1999)
Research
* The density of breeding pairs in different biomes, particularly in areas surveyed before, and in areas where SABAP2 suggests declines, needs to be quantified.
* Revised density estimates should be applied to obtain a more accurate regional population size.
* Effectiveness of awareness campaigns regarding this, and other raptors species, should be evaluated.
