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GENETIC MANAGEMENT GUIDELINES

Black Wildebeest Connochaetes gnou

The black wildebeest Connochaetes gnou (Zimmermann, 1780) is endemic to South Africa and was driven to near extinction in the early 1900’s due to over-exploitation, disease outbreaks and habitat destruction (Von Richter, 1974). A severe drought in 1933 caused the population to go through a second bottleneck and by 1938 there were only an estimated 300 animals remaining (Kirkman, 1938). Numbers have subsequently recovered and according to the IUCN, the population is currently listed as least concern and total population size is estimated at 11,158 animals (IUCN, 2017). They have been widely reintroduced on nature reserves and private farms throughout their natural distribution range (including Eswatini and Lesotho). Black wildebeest have also been introduced outside their natural distribution range, with animals currently present on privately owned farms in Namibia and Botswana (Grobler et al., 2018; Liu et al., 2024). For permitting purposes in southern Africa, Namibia and South Africa currently utilise Connochaetes gnou. There is only one recognised species with no ESUs or GMUs. Figure 1 illustrates the geographic distribution of the species.

Download Black Wildebeest Species Guidelines
Figure 1: Natural distribution of black wildebeest (Connochaetes gnou) in green shading. Points represent a locality which has been sampled for genetic data. The inset indicates the part of Africa shown in the main map. Distribution data source: Birss, C., Rushworth, I., Collins, N. B., Peinke, D. & Buijs, D. 2017. Inferred natural distribution ranges of certain large mammals in South Africa. Unpublished GIS coverage.

Management Level

Subspecies

No subspecies are recognised at present.

Evolutionarily Significant Units (ESUs)

No ESUs are recognised at present.

Genetic Management Units (GMUs)

No GMUs are recognised at present.

Management Boundaries

See Figure 1 for visual representation. Text descriptions follow.
  • Connochaetes gnou: Endemic to South Africa, eSwatini and Lesotho. Introduced into Namibia.

The species formerly occurred in Lesotho, eSwatini and South Africa (the Northern Cape, Western Cape, Eastern Cape, throughout the Free State, northward into the North West province, Gauteng and Mpumalanga, extending into western KwaZulu-Natal).

Genetic Risk

  • Global population Nc: 13,593-15,859 (Shrader and da Silva 2025; Vrahimis et al. 2017).
  • South African population Nc: 9,393-10,959 (Shrader and da Silva 2025)
  • Genetic indicators are calculated at species level as there are no GMUs or ESUs within the species.
  • If values are reported as a range, the average is used for subsequent calculations.

Table 1. Effective population size, Ne500 indicator, and confidence in the values calculated per ESU for black wildebeest. Colour of the ESU label is linked to the colour used in Figure 1. Colour of Ne500 and confidence text corresponds to positive (green) or negative  interpretation (orange/red). Overall Ne500 indicates the proportion of the total ESUs that have an Ne over 500.

Genetic Indicators
  • Ne500 indicator1
  •  
    • C. gnou Ne was based on genetic data from Liu et al. 2024. For comparative context, individuals: 22,655, comprising 15,655 in South Africa (Shrader and da Silva 2025) and >7,000 in Namibia (Vrahimis et al. 2017). With assumed maturity percentage of 60-70 % (Shrader and da Silva 2025; Vrahimis et al. 2017), Nc: 13,593-15,859. 

C. gnou has an Ne above 500 which indicates the species will maintain genetic diversity, assuming gene flow is maintained between populations, thus indicating lower genetic risk.

  • Proportion of populations maintained (PM2):
    • The global populations of the black wildebeest do not have any GMUs or ESUs and are endemic to South Africa, therefore the proportion of populations maintained globally: 1/1 = 1.
Diversity Loss
  • Functional variation: There is risk of functional variation loss due to intensive management of the species that are often bred in small founder groups. Hunting and diseases also pose risk to potentially functionally adapted populations (Grobler et al. 2018). Due to this, there has likely been a loss of traits that were adapted to specific habitats. 
  • Divergent lineages: There is little risk of losing current divergent lineages due to high effective population numbers and the current lack of any clear genetic structuring within the species.
  •  
Hybridisation/introgression
  • There is risk of hybridisation for black wildebeest with the closely related species, blue wildebeest (Power 2014). Some game ranches still stock the two species together and introgression is seen within the blue wildebeest genome (Grobler et al. 2018). There are at least 1,347 individuals that are purely black wildebeest within South Africa (Shrader and da Silva 2025). There are signals of historic hybridisation as well as current extant hybrids (Grobler et al. 2018).
Lower turnover/constraints on adaptive opportunities
  • Black wildebeest faced near extinction in the early 20th century, but have since recovered. Signals of this historical bottleneck can still be seen in their genetics, with the species having a lower genetic diversity than blue wildebeest (Grobler et al.2018). Fragmented populations due to game ranching exist across their range which could have constraints on gene flow and therefore adaptive opportunities.
In situ genetic threat level
  • In situ Risk (Moderate) 

Black wildebeest are seen to be increasing in population number across their distribution and have an effective population size above 500 (Vrahimis et al. 2017). Hybridisation with blue wildebeest is the most significant threat to their genetic diversity. With facilitation of gene flow between populations and caution towards mixing any potential hybrids, risk is moderate. For more threats, see the IUCN Red List and South African Red List.

  • Confidence in in situ threat level
    • Confidence score (High)

Confidence is high as the assessment is based on IUCN and regional assessment  data from within the last decade (Vrahimis et al. 2018; Shrader and da Silva 2025) as well as scientific papers on the species genetics using microsatellites (Grobler et al. 2018). 

Ex situ representation
  • Black wildebeest are held in 22 institutions, across 14 countries (North, South, and Central America, Europe, and Asia) with the majority in Europe. The total number of individuals is 114 (Vrahimis et al. 2017). 
  • Populations within European zoos may represent genetics of the species before large-scale translocation occurred within South Africa as were founded in the 1950s and 60s, therefore not containing hybrid individuals (Shrader and da Silva 2025).

Figure 2. Effective population size compared to confidence in the value. Colour of points and labelling corresponds to Figure 1 and Table 1. Dashed lines divide the x axis into above and below Ne500, and the y axis into low and high confidence. ESUs in the low confidence quadrant should be further surveyed to increase confidence in the evaluation. Those with high confidence below Ne500 should have increased genetic management.

1 Proportion of populations within species with an effective population size (Ne) greater than 500

(https://www.gbf-indicators.org/metadata/headline/A-4)

2 Proportion of populations maintained within species

(https://ccgenetics.github.io/guidelines-genetic-diversity-indicators/docs/2_Theoretical_background/PM-indicator.html)

Management Guidelines

  • Black wildebeest should be managed as a metapopulation.
  • If both blue- and black wildebeest are (or were) kept on the same property, all animals should be genetically tested before translocation to ensure no hybrid individuals are moved.
  • No imports/exports from/to Namibia.
  • The species is indicated to have an Ne > 500 under the assumption of gene flow. Therefore, management must strive to facilitate natural migration and gene flow between isolated populations, while taking cognisance of the other guidelines above.

IUCN Status:

  • Global: Least concern (indicated below).
  • South Africa: Least concern.

Limitations & Assumptions:

  • Black wildebeest has been widely translocated within and outside of its natural distribution range without taking hybridisation with blue wildebeest into account. Therefore, admixed individuals may have been used as founders of new black wildebeest populations as well as mixed with pure black wildebeest individuals.

Priority Research:

  • A more powerful panel of molecular markers is required to increase the confidence with which hybrids (especially 2nd or 3rd generation backcrosses) can be detected and to preserve the genetic integrity of the species.
  • Wider sampling from localities holding the species.

Cited references:

  • Grobler, P. et al. (2018). Assessing introgressive hybridization between blue wildebeest (Connochaetes taurinus) and black wildebeest (Connochaetes gnou) from South Africa. Conservation Genetics 19, 981-993. doi.org/10.1007/s10592-018-1071-x.
  • Grobler, J. P. et al. (2005). The genetic status of an isolated black wildebeest (Connochaetes gnou) population from the Abe Bailey Nature Reserve, South Africa: microsatellite data on a putative past hybridization with blue wildebeest (C. taurinus). Mammalian Biology 70, 35-45. doi.org/10.1078/1616-5047-00174.
  • Kirkman, A. H. (1938). Conservation notes. Connochaetes gnou. Journal of the Society of the Preservation of the Wild Fauna of the Empire 35, 50. 
  • Liu, X. et al. (2024). Introgression and disruption of migration routes have shaped the genetic integrity of wildebeest populations. Nature Communications 15, 2921. doi.org/10.1038/s41467-024-47015-y.
  • Von Richter, W. (1974). Connochaetes gnou. Mammalian Species 50, 1-6.  https://doi.org/10.2307/0.50.1.
  • Vrahimis, S., Grobler, P., Brink, J., Viljoen, P. & Schulze, E. 2017. Connochaetes gnou. The IUCN Red List of Threatened Species 2017: e.T5228A50184962. https://dx.doi.org/10.2305/IUCN.UK.2017-2.RLTS.T5228A50184962.en. [Accessed on 15 February 2026].

Additional references:

  • Corbet, S. W. & Robinson, T. J. (1991). Genetic Divergence in South African Wildebeest: Comparative Cytogenetics and Analysis of Mitochondrial DNA. The Journal of Heredity 82, 447-52. doi.org/10.1093/oxfordjournals.jhered.a111126.
  • Grobler, P. et al. (2018). Assessing introgressive hybridization between blue wildebeest (Connochaetes taurinus) and black wildebeest (Connochaetes gnou) from South Africa. Conservation Genetics 19, 981-993. doi.org/10.1007/s10592-018-1071-x.
  • Grobler, J. P. et al. (2005). The genetic status of an isolated black wildebeest (Connochaetes gnou) population from the Abe Bailey Nature Reserve, South Africa: microsatellite data on a putative past hybridization with blue wildebeest (C. taurinus). Mammalian Biology 70, 35-45. doi.org/10.1078/1616-5047-00174.
  • Liu, X. et al. (2024). Introgression and disruption of migration routes have shaped the genetic integrity of wildebeest populations. Nature Communications 15, 2921. doi.org/10.1038/s41467-024-47015-y.

Consultation:

  • IUCN SSC Conservation Genetics Specialist Group
  • IUCN SSC Antelope Specialist Group

Acknowledgements:

We are grateful to Profs Paul Grobler and Rouvay Roodt-Wilding and Dr David Mallon for their valuable comments and for taking the necessary time and effort to critically review the initial guidelines.

Queries:

If you have any additional questions related to these guidelines, please contact ConGen Africa at info@congenafrica.com.

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