Archived 2012-2013 topics: Black Bustard (Eupodotis afra): eligible for uplisting?

Black Bustard Eupodotis afra (BirdLife species factsheet) is restricted to the non-grassy, winter rainfall or mixed winter-summer rainfall Fynbos and Succulent Karoo biomes, and the extreme south of the Nama Karoo biome, in a narrow strip along the southern and western coastlines of South Africa (Hofmeyr 2012). It also occurs in semi-arid scrub and dunes with succulent vegetation, and extends into renosterveld scrub and semi-arid karoo (del Hoyo et al. 1996, Hockey et al. 2005). It occurs occasionally in cultivated fields with nearby cover (Hockey et al. 2005). It is currently listed as being of Least Concern, on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN criteria. However, concern has recently been expressed over this species’s status, as there is evidence that it is declining in abundance (per Hofmeyr 2012). Following recent research, it has been recommended that the species be classified as Vulnerable because of past and probable future decreases in its population and because of its susceptibility to on-going land conversion, climate change and possibly increased predation (Hofmeyr 2012). For example, the species is likely to have suffered major habitat loss through the conversion of land to cultivation in the western Cape lowlands (Hockey et al. 2005). The comparison of mapped data from the first and second Southern African Bird Atlas Projects (SABAP1, 1987–1992 and SABAP2, 2007–) indicates that the species declined in abundance in c.80% of its range (Hofmeyr 2012). A negative trend was confirmed by occupancy modelling using the same atlas data, and data from Coordinated Avifaunal Roadcounts indicate declines between 1997 and 2010 in Overberg and Swartland, while it may have increased in the Eastern Cape Karoo region (Hofmeyr 2012). Hofmeyr (2012) argues that these data and analyses constitute convincing evidence that the population of the species declined overall between 1992 and 2010, although the decline may have decelerated from 2008 onwards. Based on these conclusions, Hofmeyr (2012) recommends that the species be considered for listing as Vulnerable under criterion A4, on the basis of a suspected reduction in population size of at least 30% over a three-generation period stretching from the past into the future. This is based on a suspected generation length of at least five years (Hofmeyr 2012); however, BirdLife International estimates the species’s generation length to be c.10.3 years, and thus the three-generation trend period to be c.31 years. Therefore it is possible that the species is in rapid to very rapid decline over a period of three generations (31 years). Additional information is requested on this species, including more input on the severity of threats and the likely population trend over the past 31 years, next 31 years, and/or a window of 31 years stretching from the past into the future. Under criterion A, a decline approaching 30% (typically 25-29%) over three generations would likely make the species eligible for listing as Near Threatened, while a decline of 30-49% would suggest the species should be listed as Vulnerable, and a decline of 50-79% would probably warrant uplisting of the species to Endangered. References: del Hoyo, J., Elliott, A. and Sargatal, J. (1996) Handbook of the birds of the world, Vol 3: Hoatzin to Auks. Barcelona, Spain: Lynx Edicions. Hockey, P. A. R., Dean, W. R. J. and Ryan, P. G. (2005) Roberts birds of southern Africa. 7th edition. Cape Town, South Africa: Trustees of the John Voelcker Bird Book Fund. Hofmeyr, S. (2012) Impacts of environmental change on large terrestrial bird species in South Africa: insights from citizen science data. PhD thesis, University of Cape Town.

This entry was posted in Africa, Archive, Bustards and tagged . Bookmark the permalink.

3 Responses to Archived 2012-2013 topics: Black Bustard (Eupodotis afra): eligible for uplisting?

  1. Up to date analysis of the SABAP data (April 2013) indicates the situation may be more serious than I concluded in my thesis. The Eastern Cape population appears to be declining slightly overall, while the decline in the Northern Cape and especially the Western Cape appears to be more significant than my analysis of data submitted up until February 2012 indicated.

    I would also like to bring to the attention of BirdLife International the fact that, according to the recognised authority in southern Africa, this species (known here as the Southern Black Korhaan) and the Northern Black Korhaan / Whitequilled Bustard have been separated from the other southern African korhaans and placed in the genus Afrotis. The Red-Crested Korhaan / Bustard has also been placed in a separate genus: Lophotis.

  2. Part of the reason why the more vulnerable status of this species was probably missed in earlier IUCN assessments is that originally the Black Bustard, Eupodotis afra now Afrotis afra, was included as part of the Northern Black Korhaan, Eupodotis afraoides now Afrotis afraoides, population. The split from one species, the Black Korhaan, into two separate species, initially called the Black Korhaan and White-quilled Korhaan and more recently the Southern Black Korhaan (Black Bustard, Afrotis afra )and Northern Black Korhaan only occurred in 1994 ( Crowe et al. 1994). The Northern Black Korhaan has a much larger range than the Southern Black Korhaan and so while both species were considered to be part of the same population any decline in the Southern Black Korhaan in the south would not have been obvious. The range of the Southern Black Korhaan (Afrotis afra) is much smaller and the habitat information collected by the Coordinated Avifaunal Roadcounts (CAR) project indicates that this species is largely dependent on indigenous vegetation. As mentioned by Hofmeyr (2012) data from the CAR project indicates declines between 1997 and 2010 in Overberg and Swartland, areas in which the intensity of agricultural cultivation has increased in recent years. The decline of this species in these important wheat growing areas is probably linked to a decrease in available indigenous vegetation, the “patches” of indigenous vegetation have probably not only decreased in size but also become more isolated. The CAR project is still active and the low densities have continued since Sally Hofmeyr completed her thesis, apart from an increase in the 2012 winter density in the Swartland. The higher densities in the Eastern Cape Karoo precinct may be related to less intensive land use (predominantly grazing) in this region relative to the more mesic coastal and western precincts (Callan & Spottiswoode 2003). There has also been an increase in the number of game farms in the Eastern Cape province. The predominance of the “veld” habitat type (i.e. indigenous vegetation) in the Eastern Cape Karoo precinct is evident in the habitat analysis of earlier CAR data in Young et al. (2003). Sally Hofmeyr’s thesis analyses indicated that this species may have increased in this region where more indigenous vegetation is available, but her recent comment indicates that it may be declining overall now.
    I would certainly recommend that the status of the Black Bustard, Afrotis afra, be uplisted.
    References
    Callan, C. & Spottiswoode, C.N. 2003 Black Korhaan Eupodotis afra. In: Big Birds on Farms: Mazda CAR Report 1993-2001. Young, D.J., Harrison, J.A., Navarro, R.A., Anderson, M.D. & Colahan, B.D. (eds), pp.61-64. Avian Demography Unit, Cape Town.
    Crowe, T.M., Essop, M.F., Allan, D.G., Brooke, R.K. & Komen, J. 1994. ‘Overlooked’ units of comparative and conservation biology: a case study of a small African bustard, the Black Korhaan Eupodotis afra. Ibis 136: 166-175.
    Hofmeyr, S. (2012) Impacts of environmental change on large terrestrial bird species in South Africa: insights from citizen science data. PhD thesis, University of Cape Town.
    Young, D.J., Harrison, J.A., Navarro, R.A., Anderson, M.D. & Colahan, B.D. (eds). 2003. Big Birds on Farms: Mazda CAR Report 1993-2001. Avian Demography Unit, Cape Town.

  3. Jessica Shaw says:

    As part of my PhD, I conducted an extensive large terrestrial bird road census across the Karoo, South Africa (Shaw 2013), and compared results with those from a similar study conducted in the 1980s (Allan 1994). The findings support those discussed in previous posts, with evidence for a marked population decline of Southern Black Korhaans in the Succulent Karoo between the two surveys. I therefore support uplisting of this species.

    Refs
    Allan, D.G. 1994. The abundance and movements of Ludwig’s Bustard Neotis ludwigii. Ostrich 65: 95-105.
    Shaw, J.M. 2013. Power line collisions in the Karoo: Conserving Ludwig’s Bustard. PhD thesis, University of Cape Town.

Comments are closed.