Geronticus calvus (Southern bald ibis)

Geronticus calvus (Southern bald ibis)

Kalkoenibis [Afrikaans]; Umcwangele [Xhosa]; umXwagele (generic term for ibis), uNkondlo [Zulu]; Lesuhla-ngeto, Mokhotlo [South Sotho]; Kaapse ibis [Dutch]; Ibis du Cap [French]; Glattnackenrapp [German]; Ibis-calvo [Portuguese]

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Deuterostomia > Chordata > Craniata > Vertebrata (vertebrates) > Gnathostomata (jawed vertebrates) > Teleostomi (teleost fish) > Osteichthyes (bony fish) > Class: Sarcopterygii (lobe-finned fish) > Stegocephalia (terrestrial vertebrates) > Tetrapoda (four-legged vertebrates) > Reptiliomorpha > Amniota > Reptilia (reptiles) > Romeriida > Diapsida > Archosauromorpha > Archosauria > Dinosauria (dinosaurs) > Saurischia > Theropoda (bipedal predatory dinosaurs) > Coelurosauria > Maniraptora > Aves (birds) > Order: Ciconiiformes > Family: Threskiornithidae


Southern bald ibis, Wakkerstroom, South Africa. [photo Warwick Tarboton ©]

Distribution and habitat

Endemic to the Great Escarpment, from the Limpopo Province through Swaziland and Mpumalanga to eastern Free State, Lesotho and KwaZulu-Natal. It generally prefers high-altitude treeless grassland and recently burnt, ploughed or heavily grazed fields.

Distribution of Southern bald ibis in southern Africa, based on statistical smoothing of the records from first SA Bird Atlas Project (© Animal Demography unit, University of Cape Town; smoothing by Birgit Erni and Francesca Little). Colours range from dark blue (most common) through to yellow (least common). See here for the latest distribution from the SABAP2.

Predators and parasites

Predators of chicks
- Buteo rufofuscus (Jackal buzzard)
- Bubo capensis (Cape eagle-owl)
- Aquila verreauxii (Verreauxs' eagle, Black eagle)
- Corvus albus (Pied crow)

Movements and migrations

Largely resident, although it sometimes disperses after breeding in the period from August-December.

Food

It mainly eats insects, foraging in small flocks of usually 5-15, rarely up to 100 birds, probing the ground and snapping up prey. The following food items have been recorded in its diet:

Invertebrates
- insects
  - grasshoppers (Orthoptera)
  - Coleoptera (beetles)
  - caterpillars (larval stage of Lepidoptera)
    - Busseola fusca (Maize stalk borers)
- earthworms
- snails
Vertebrates
- frogs
- small mammals
- birds
- carrion (rarely)

Breeding

Monogamous, although it rarely copulates with a second mate. It almost invariably breeds in colonies of 2-72 pairs.
The nest (see image below) is built by the female with material provided by the male, consisting of a flimsy platform of branches and sticks, lined with finer material and placed on a ledge or pothole on a cliff.


Southern bald ibis at its nest, Wakkerstroom, South Africa. [photo Warwick Tarboton ©]

Egg-laying season is from July-January, peaking from August-September when there is plenty of burnt grassland to forage on.
It lays 1-3 eggs, which are incubated by both sexes for roughly 27-31 days.
The chicks are fed by both parents by regurgitation, taking their first flight at about 55 days old and becoming fully independent approximately five days later.

Threats

Vulnerable or Threatened, largely due to commercial afforestation, intensive agriculture, acid rain, open-cast mining and human interference at breeding colonies; its world population is estimated to be 5000-10000 individuals.

References

Hockey PAR, Dean WRJ and Ryan PG 2005. Roberts - Birds of southern Africa, VIIth ed. The Trustees of the John Voelcker Bird Book Fund, Cape Town.