• Summary
• Text account
• Data table and detailed info
• Distribution map
• Climate Change maps
• Reference and further resources

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2024	Near Threatened	A3c; C2a(ii)
2016	Vulnerable	C1+2a(ii)
2013	Vulnerable	A3c+4c;C2a(ii)
2012	Vulnerable	A3c+4c;C2a(ii)
2008	Vulnerable	A3c; C2a(ii)
2006	Vulnerable
2004	Vulnerable
2000	Vulnerable
1996	Vulnerable
1994	Vulnerable
1988	Threatened

Migratory status	not a migrant	Forest dependency	does not normally occur in forest
Land-mass type	continent	Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	228,000 km2	medium
Extent of Occurrence (non-breeding)	301,000 km2	medium
Number of locations	200-500	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	7000-8000 mature individuals	good	estimated	2023
Population trend	stable	good	inferred	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	0-29%	-	-	-
Generation length	9.6 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: Previous population estimates (Manry, 1985, Henderson 2015, Colyn et al. 2020) are the result of extrapolations from the number of breeding adults at monitored colonies; that used in the previous Red List assessment (BirdLife 2016) of 3,300-4,000 mature individuals was based on Henderson (2015). But these estimates are now thought to have underestimated the true population size. The underlying data here is the number of pairs that are breeding at a colony in a particular year, whereas we now know that a large proportion of the mature population do not breed each year and are therefore not available to be counted (Lee et al. in prep.). Conservatively accounting for the missed proportion of individuals by using the single highest count per pentad in the citizen science dataset (SABAP2) and also employing a conservative range estimate Lee et al. (in prep.) propose that the likely minimum global population is 7,000 individuals in the breeding season and 11,000 individuals outside the breeding season, and 10,000 individuals across seasons. The ratio of adults to immatures based on the colony data is between 70-80% (Lee et al. in prep.). Hence the minimum population size is likely to be 7,000-8,000 mature individuals.
There is no evidence for a change in the reporting rate between the two SABAP atlas periods up to 2014 and between 2015 and 2022 the species appears to have been slightly more widely reported (Lee et al. in prep.). Within the reporting period for SABAP2 a dynamic occupancy model showed no linear trend in probabilities of colonisation nor extinction, with probability of colonisation slightly higher than extinction (Lee et al. in prep.). An analysis of species distribution models did show that the probability of the species being recorded in the second SAPAB2 period (2015-2022) was slightly lower than in the first (2007-2014). Colony monitoring indicated little change in overall numbers of nests at monitored sites. 26 of 319 colonies found since 2000 have been abandoned, but new colonies are also being found and two small abandoned sites have since been recolonised (Lee et al. in prep.).

Trend justification: Overall, monitoring data from multiple sources indicates that the species' population has been likely stable over the past few decades (Lee et al. in prep.), suggesting that recorded colony abandonments (Colyn et al. 2020) largely result in the redistribution of breeding adults. The abandonment of colonies may still be a sign that the population will decline (Lee et al. in prep.) and there may be a delay before it is evident at the scale of the analysis conducted. The population impacts of grassland habitat conversion exacerbated by climate change are uncertain but the future projection of an overall contraction in suitable area of habitat equivalent to 29% over three generations, predominately in the north and west of the currently occupied breeding range, and ongoing conversion of grassland habitat suggests that slow to moderately rapid declines may occur in the future (Colyn et al. 2020, Lee et al. in prep).

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Eswatini	extant	native	yes
Lesotho	extant	native	yes
South Africa	extant	native	yes

Country/Territory	IBA Name
Eswatini	Mahamba Mountain
Eswatini	Malolotja Nature Reserve
Lesotho	Liqobong
Lesotho	Mafika - Lisiu
Lesotho	Sehlabathebe National Park
Lesotho	Sehonghong and Matebeng
Lesotho	Upper Quthing Valley
Lesotho	Upper Senqu River
South Africa	Alexpan
South Africa	Amersfoort - Bethal - Carolina District
South Africa	Blyde River Canyon
South Africa	Chrissie Pans
South Africa	Golden Gate Highlands National Park
South Africa	Grasslands
South Africa	Hlatikulu
South Africa	Hluhluwe-iMfolozi Park
South Africa	Impendle Nature Reserve
South Africa	Ingula Nature Reserve
South Africa	Ithala Game Reserve
South Africa	Kaapsehoop
South Africa	KwaZulu-Natal Mistbelt Grasslands
South Africa	Maloti Drakensberg Park
South Africa	Matatiele Nature Reserve
South Africa	Rooiberge-Riemland
South Africa	Songimvelo Nature Reserve
South Africa	Steenkampsberg
South Africa	Sterkfontein Dam Nature Reserve
South Africa	Umvoti Vlei

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Arable Land	suitable	non-breeding
Artificial/Terrestrial	Arable Land	suitable	breeding
Artificial/Terrestrial	Pastureland	suitable	non-breeding
Artificial/Terrestrial	Pastureland	suitable	breeding
Grassland	Subtropical/Tropical High Altitude	major	non-breeding
Grassland	Subtropical/Tropical High Altitude	major	breeding
Rocky areas (eg. inland cliffs, mountain peaks)		major	breeding
Altitude	10 - 2900 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Agro-industry farming	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Wood & pulp plantations - Agro-industry plantations	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem conversion
Biological resource use	Hunting & trapping terrestrial animals - Intentional use (species is the target)	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species mortality
Climate change & severe weather	Habitat shifting & alteration	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation
Energy production & mining	Mining & quarrying	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation, Ecosystem conversion
Human intrusions & disturbance	Work & other activities	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species disturbance
Pollution	Agricultural & forestry effluents - Herbicides and pesticides	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Unknown		Unknown
		Stresses Indirect ecosystem effects, Ecosystem degradation, Reduced reproductive success
Residential & commercial development	Housing & urban areas	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem conversion
Transportation & service corridors	Utility & service lines	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Negligible declines		Low Impact: 4
		Stresses Species mortality

Purpose	Scale
Food - human	subsistence, national
Pets/display animals, horticulture	international

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Recommended citation
BirdLife International (2024) Species factsheet: Southern Bald Ibis Geronticus calvus. Downloaded from https://datazone.birdlife.org/species/factsheet/southern-bald-ibis-geronticus-calvus on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 22/12/2024.