A total of 499 breeding pairs of the Southern Bald Ibis Geronticus calvus at 73 sites were recorded in the Free State, South Africa. The breeding density was calculated as 15 pairs per 1000 km². The size of the breeding sites ranged from one to 57 pairs. Only 11 breeding sites (14%) contained ten or more breeding pairs, while 12 sites (15%) consisted of single breeding pairs only. Adult: immature birds ratio was determined as 1:0.1, while proportion of breeding versus non-breeding adults was 1:0.4. In the Free State province Southern Bald Ibises typically inhabit areas in close proximity to natural montane grassland along cultivated lands (maize mainly). All breeding colonies were situated on sandstone cliffs, most of them in close proximity to water bodies and villages. Other bird species, including birds of prey, were found to nest in close proximity to the ibis colonies. Egg-laying in the Southern Bald Ibis extended from the end of July to the end of October, with most clutches being completed during the second half of August and in September. The mean clutch size was calculated as 2.2 (n = 120), hatching success — 69% (n = 67), fledging success — 20% (n = 52) and reproductive success — 18% (n = 84). Most chick losses are attributed to natural predation, especially by Black Eagles.
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