Justification of Red List Category
This species is listed as Vulnerable because it has a small population which is believed to be declining owing to habitat loss and degradation, with projected future declines due to climate change.
Henderson (2015) estimated a total population of 6,500-8,000 birds, including c.1,650-2,000 breeding pairs i.e. 3,300-4,000 mature individuals.
South African populations may have increased between the late 1960s and the early 1980s, but the Lesotho population may be declining. Overall, the species's population is suspected to have decreased at a moderate rate because of habitat loss and degradation. Population declines are projected to occur in the future if current rates of habitat loss continue and due to climate change.
Geronticus calvus is restricted to Lesotho, north-east South Africa and west Swaziland. The core range lies in the north-eastern Free State, Mpumalanga and the KwaZulu-Natal Drakensberg. It was formerly widespread in the Eastern Cape and there is evidence that it is starting to recolonize the area from Lesotho (Boshoff and van Niekerk 2007). In South Africa, there are over 150 colonies (Henderson 2015), although c.25% of the breeding population occurs at just 5 colonies. In Swaziland, there are three main breeding colonies, supporting at least 10 pairs each, and a total population of c.110 birds. In Lesotho, the population, with several known breeding colonies, is probably in the low thousands. South African populations may have increased between the late 1960s and the early 1980s, but the Lesotho population may be declining. It has been suggested that the total population is 6,500-8,000 individuals and 1,600-2,000 breeding pairs at 208 colonies (Henderson 2015). This species may have suffered a decline in AOO because, of 35 colonies assessed, 26 colonies declined in size (Henderson 2015), and 12 colonies have been completely abandoned over the past 15 years (Colyn et al. in prep.).
It prefers high rainfall (>700 mm p.a.), sour and alpine grasslands, characterised by an absence of trees and a short, dense grass sward. It also occurs in lightly wooded and relatively arid country. It forages preferentially on recently burned ground, also using unburnt natural grassland, cultivated pastures, reaped maize fields and ploughed areas. It has a varied diet, mainly consisting of insects and other terrestrial invertebrates. It has high nesting success on safe, undisturbed cliffs.
Threats include human interference with breeding colonies and habitat loss through commercial afforestation, intensive crop farming, open-cast mining, acid rain and dense human settlement. Climate change alone is projected to cause a decline in EOO of 20% by 2050 (Colyn et al. in prep.). Pesticide contamination is a potential threat as is exploitation for traditional medicinal/ceremonial purposes in Lesotho. Several predatory bird species have been recorded raiding colonies for adults and young. The species's habit of using electricity pylons as roost sites in certain areas results in some mortality from collisions with powerlines (van Rooyen 2005).
Conservation Actions Underway
CITES Appendix II. It has full legal protection in South Africa where it breeds in several protected areas. In Swaziland, Malolotja Nature Reserve holds a breeding colony. In Lesotho, it is recorded from Setlabathebe National Park. Roosts on pylons result in both the mortality of some birds and faults in powerlines, thus it has been recommended that bird guards be installed on the most affected pylons and anti-collision devices be fitted to the earth wire near roost sites (van Rooyen 2005). Under the BirdLife South Africa Southern Bald Ibis Species Champion Project a number of colonies were monitored between 2007 and 2011 to assess population trends (Henderson 2015) and monitoring continues across a number of site in South Africa (R. Colyn in litt. 2016). Additionally, from July 2016, an educational awareness programme has been implemented across schools in South Africa in its core range to help reduce disturbance and the collecting of eggs and chicks (R. Colyn in litt. 2016). Also distribution studies (Colyn et al. in prep.) and studies into the home range, foraging and dispersal behaviour of this species, are underway (R. Colyn in litt. 2016). It is listed as Vulnerable in The 2015 Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland (Henderson 2015).
78 cm. Large, glossy blue-black ibis. Adult has bald red head with white face. Long, red, decurved bill. Red legs and feet. Coppery patches on forewings. Wings long and elongated in flight, and beat rapidly in between gliding. Immature matt black, lacking any colour on head and bill. Similar spp. Smaller Glossy Ibis Plegadis falcinellus has chestnut head. Voice Distinctive, high-pitched, turkey-like keeaaw-klaup-klaup. Hints Gregarious. Forages in flocks of up to 50 individuals.
Text account compilers
Allinson, T, Ashpole, J, Ekstrom, J., Khwaja, N., Pilgrim, J., Shutes, S., Taylor, J., Westrip, J.
Colyn, R., Smit-Robinson, H.
BirdLife International (2021) Species factsheet: Geronticus calvus. Downloaded from http://www.birdlife.org on 23/04/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/04/2021.