Rationale
(Changed due to Not applicable)
The regional population of Marabou Stork Leptoptilos crumeniferus has been quantified at 340-520 mature individuals, thus satisfying criterion D1 for regionally Vulnerable (population size estimated to number less than 1 000 mature individuals). However, the fact that the regional population receives an immigration of individuals capable of reproducing in the region has resulted in the species being downgraded from regionally Vulnerable to regionally Near Threatened. The species breeds only at two localities in the region.
Distribution
The Marabou Stork occurs throughout sub-Saharan Africa. Within the region, it is primarily a non-breeding visitor from farther north in Africa, with only scattered and sporadic breeding records known from the Kruger National Park (Whyte et al. 1993, Anderson 2005) and one established breeding site in Hlane Royal National Park in eastern Swaziland (Reilly and Wasdell 1965, Monadjem et al. 2012). Birds have also recently started breeding at Pongolo Game Reserve (northern KwaZulu-Natal), with at least some of these breeding birds having fledged from the Swazi population (A Monadjem unpubl. data). In contrast to the rest of Africa, Marabou Storks are largely confined to large conservation areas within the region (Anderson and Herremans 1997). Dispersing birds can cover extensive distances of up to 1 500 km (Monadjem et al. 2008). The breeding population in Swaziland, as well as birds from outside of the region, possibly act as a source for the remainder of the non-breeding population in South Africa. The EoO has decreased by 6.2% between 1997 and 2014, while the AoO has decreased by 26.9%.
Population
The global population has been estimated at 200 000-500 000 mature individuals (Dodman and Diagana 2006). Barnes (1998) estimated there to be 340-512 mature individuals distributed across five sites in South Africa and one site in Swaziland. The current Swaziland population is less than 40 mature individuals (Monadjem et al. 2012). In the absence of any observed declines, the regional population is estimated to be between 340-520 mature individuals. The confidence in this estimate is medium.
Population trend
Throughout its range in Africa, the Marabou Stork's population is suspected to be increasing, mainly due to the species' ability to make use waste as a food source (BirdLife International 2014), although there is evidence of some urban populations decreasing (A Monadjem pers. comm.). Within the region, it is suspected that the population has remained stable over the past three generations. The confidence in this estimate is medium.
Threats
The removal of predators from large portions of the South African veld may have impacted upon this species (Barnes 2000). Nikolaus (2001) reported that Marabou Storks are utilised as a food source in Nigeria, although it is not known if this occurs within the region. The Marabou Stork's predilection for scavenging from informal rubbish dumps and waste disposal sites may expose it to harmful substances and pollutants. Likewise, when feeding on carrion it is potentially susceptible to the same extensive suite of threats faced by vultures, such as deliberate or accidental poisoning. As with other large birds, power-line collisions may pose a threat.
Conservation
Underway
There are currently no conservation measures underway. The Marabou Stork is well represented in the IBA network, with important sites including e.g. Mapungubwe National Park (SA001), Kruger National Park (SA002), Pilanesberg National Park (SA023) and parts of iSimangaliso Wetland Park, e.g. Mkuze Game Reserve (SA057). Both the current breeding sites are recognised and protected IBAs: Pongolo Game Reserve (SA055) in northern KwaZulu-Natal, and Hlane Royal National Park in eastern Swaziland (SW002).
Proposed
It is recommended that annual monitoring efforts of the breeding colonies at Hlane Royal National Park and Pongolo Nature Reserve continue. Birdwatchers should be encouraged to document congregations of Marabou Storks and submit this information, in order to identify important sites for the species. Additional conservation measures, and the need for them, will be determined by results of the research priorities recommended here.
Research
* Investigation into the relationship between the Swaziland breeding colony and birds seen in Kruger National Park, Adjacent Private Nature Reserves and elsewhere in South Africa, with a focus on source/sink relationships in the context of southern African populations, is required.
* Quantification of genetic exchange taking place between various meta-populations in southern Africa and the rest of Africa would be beneficial.
* Potential but unconfirmed threats (e.g. poisoning and power-line collisions) should be assessed.
