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The Southern Bald Ibis Geronticus calvus satisfies the population criterion for regionally Vulnerable (population size estimated to number less than 10 000 mature individuals and a predicted continuing decline of greater than 10% in three generations).
The Southern Bald Ibis is endemic to the region, occurring in north-eastern Free State, Mpumalanga, Limpopo, inland areas of KwaZulu-Natal, most of Lesotho and western Swaziland; the species is naturally re-establishing in Eastern Cape, just south of the Lesotho border (Pocock and Uys 1967, Cooper and Edwards 1969, Bonde 1993, Allan 1997, Barnes 2005). Southern Bald Ibis have been seen as far north as Polokwane (Limpopo) and Ezemvelo Nature Reserve (Gauteng/Mpumalanga); south-west to Ladybrand (Free State); south to Lady Grey, Barkly East, Naudesnek and Lusikisiki (Eastern Cape); and east to Amatikulu Game Reserve and Hluhluwe-iMfolozi Park (KwaZulu-Natal). In Swaziland, the species occurs in the high-lying western grasslands and in two protected areas, namely Malolotja National Park and Mantenga Nature Reserve (Monadjem et al. 2003)
Between 2007 and 2011, counts were made at 166 of the known breeding sites, including 124 active colonies with a total of 3 333 birds and 689 breeding pairs (nests) recorded. Of 114 colonies with both historical (1965-2005) and recent data, 37 were found to be abandoned, i.e. no birds were present at 32% of historical sites. This provides a global estimate of c. 246 active colonies with a global population size of 7 227 ± 709 individuals. Given an average count at breeding sites of 3.96 birds per nest, this suggests around 1 825 ± 180 breeding pairs and 3 290-4 010 mature individuals. Confidence in this population estimate is high.
The regional (and global) population is in decline. Matched historical and recent counts (2007-2011) were available for 35 colonies. Of these, 26 colonies declined in size and 28 declined in numbers of nests. Conversely, seven colonies showed slight to moderate increases in size and nest counts. The average rate of decline, weighted by colony size, implies a decline in breeding adults of around 11% over the past three generations (30 years). Confidence in this population trend estimate is high.
The Southern Bald Ibis is threatened by poachers taking eggs and young from breeding ledges, by pesticides and poisoning and, in certain areas, by habitat destruction and degradation caused by open-cast mining, urban development and large-scale commercial farming (Collar et al. 1994, Barnes 2000i). Incidents of poisoning and deaths from aerial spraying and illegal pesticide use have been reported (CL Henderson pers. obs.). In certain areas, the species' habit of using electricity pylons as roost sites results in some mortality from collisions with power-lines. Hunting has also been reported as a threat.
The Southern Bald Ibis is listed as Vulnerable under the National Environment Management: Biodiversity Act, 2004 (Act 10 of 2004) and under Schedule 2: Specially Protected Wild Animal Under the Limpopo Environmental Management Act No 7 of 2003. It is listed as Vulnerable in Swaziland and is protected by the Swaziland Game Act 1991. BirdLife South Africa, with support from Eskom, has initiated a Southern Bald Ibis programme, based around the objectives of assessing threats to the species and its habitat, mitigating impacts of these threats, maintaining current population levels and establishing practical guidelines for land-owners and avitourism operators to protect breeding colonies. Regular counts of breeding colonies are being conducted, and should continue.
A Species Action Plan for the long-term conservation of the Southern Bald Ibis is recommended. As many as possible of the larger breeding colonies and feeding areas require formal and active protection. Incentives for adopting ibis-friendly farming practices need to be implemented.
The following aspects of Southern Bald Ibis ecology and conservation strategy require attention:
* Estimation of breeding success and offspring survival rates at known breeding sites.
* Mapping of movements between colonies and roosts, and maintenance of a GIS database of all colonies.
* Mapping of historical and potential foraging habitat.
* Determination of affects of different burning and grazing regimes, and pesticides, on foraging habitat.
* Research into the causes and consequences of variation in colony sizes, colony decreases, and the influence of the surrounding landscape on such trends.
* Compilation of effective conservation guidelines for land-owners with colonies on their property.