Justification of Red List Category
This species is classified as Endangered as the population is projected to have undergone a very rapid population decline due to collisions with power lines, a trend which is set to continue into the future as the power grid in southern Africa expands and successful mitigation measures are yet to be implemented.
Allan (1994) carried out a census in the 1980s and estimated the entire population of Ludwig’s Bustard at 56,000–81,000 individuals, of which 50–75% were thought to occur in South Africa (Anderson 2000). A recent repeat of this census (2010-2012) in the South African part of the range estimated the current South African population at 114,000 birds (95% CI 87,000-148,000) (Shaw et al. 2015), and so the total population is inferred to fall within the range of 100,000-499,999 individuals. While there is therefore no clear evidence that the population has declined as projected (Jenkins et al. 2011), there is not enough information with which to understand the trend; Allan’s (1994) estimate was probably a significant underestimate, and the confidence intervals of the current estimate are very wide. Work is underway in Namibia to estimate the size of the Namibian population.
Based on collision rates with power lines from two areas, the best-case scenario indicates a decline of 51% over three generations in South Africa, which holds 50-75% of the global population (Jenkins et al. 2011). Given that power lines collisions also occur in Nambia (A. Scott and M. Scott in litt. 2010), and effective mitigation measures are yet to be implemented, a decline of 50-79% is estimated over the 31 year period from 1994-2025 (three generations).
Neotis ludwigii has a large range centred on the dry biomes of the Karoo and Namib in southern Africa, being found in the extreme south-west of Angola, western Namibia and in much of South Africa (del Hoyo et al. 1996, Anderson 2000). The global population has been previously estimated at 56,000-81,000 individuals (Allan 1994). However, this estimate is now approximately 20 years old, and in this time the species is suspected to have declined rapidly as a result of collisions with overhead power lines, for which there is currently no effective mitigation (Anderson 2002, Jenkins and Smallie 2009).
This species inhabits open lowland and upland plains with grass and light thornbush, sandy open shrub veld and semi-desert in the arid and semi-arid Namib and Karoo biomes. Recent satellite telemetry and stable isotope data support earlier work (Allan 1994) that shows Ludwig’s Bustard to be nomadic and a partial migrant (Shaw 2013, Shaw and Ryan 2015), moving to the western winter-rainfall part of its range in winter. The breeding season spans from August-December, with the species nesting on bare ground with a clutch of 2-3 eggs (del Hoyo et al. 1996, Jenkins and Smallie 2009). Chick-rearing is conducted solely by females (Jenkins and Smallie 2009). The diet includes invertebrates, some small vertebrates and vegetable matter, including the berries of Lycium oxycladum. There is strong evidence that the species undergoes movement with rains in pursuit of Orthoptera hatchlings, though vegetation remains important (Allan 1994). Flocks of up to 70 individuals have been recorded (del Hoyo et al. 1996).
The primary threat to the species is collisions with overhead power lines, with potentially thousands of individuals involved in such collisions each year (del Hoyo et al. 1996, Anderson 2002, Jenkins and Smallie 2009, Jenkins 2009, Jenkins et al. 2011, Shaw 2013). Bustards have limited frontal vision so may not see power lines, even if they are marked (Martin and Shaw 2010). Collision rates on high voltage transmission lines in the De Aar area of the Karoo may exceed one Ludwig's Bustard per kilometre per year (Anderson 2002, Jenkins et al. 2009), and there is evidence for this level of mortality on transmission lines across the Karoo, indicating that the problem is widespread (Jenkins et al. 2011, Shaw 2013). Given that the extent of power lines in the Karoo is vast and expanding (Jenkins and Smallie 2009, J. Smallie in litt. 2010), with already over 17,000 km in place, it is estimated that such collisions alone are already enough to cause a rapid decline which may intensify in the future (Jenkins et al. 2011). Recent surveys on the more prolific low voltage lines have also revealed substantial levels of mortality (Shaw 2013), and in addition to power lines wind farms are currently establishing in many parts of the Karoo. Other threats to this species include deliberate hunting, capture in snares set for mammals, poisoning and disturbance, with one satellite tracked bird likely hunted (del Hoyo et al. 1996, J. Shaw unpubl. data).
Conservation Actions Underway
A research project took place at the Percy FitzPatrick Institute, University of Cape Town to: conduct a new census of the Ludwig's Bustard population in South Africa, to compare with the last assessment in the 1980s (Allan 1994); thoroughly assess the magnitude of power line mortality through regular line surveys across the Karoo; look at habitat use and patterns of local and regional movement of bustards through satellite tracking in relation to environmental conditions and the power grid; and to explore mitigation options through experimentation of line marking devices (Shaw 2013). An extensive line-marking experiment devised by the Percy Fitzpatrick Institute was put up near De Aar in 2011 in conjunction with the Eskom - Endangered Wildlife Trust Strategic Partnership to test the two current devices used in mitigation in South Africa. In Namibia, NamPower are also working to implement effective mitigation measures (A. Scott and M. Scott in litt. 2010). The species is listed as Endangered in Namibia, and South Africa, Lesotho and Swaziland (Scott et al. 2015, Shaw 2015)
Conservation Actions Proposed
Continue to raise awareness to stop hunting and to encourage the public to report mortality from power lines etc. All new infrastructure (power lines, wind turbines) should be sited and mitigated appropriately, and dangerous sections of line should be retrofitted with appropriate mitigation. Further research into mitigation measures for power line collisions, other than those being tested at the De Aar site, should be instigated as the results of such experiments take a long time to gather. Research to learn more about key life history parameters for this long-lived bird is also crucial to facilitate more accurate assessment of the impacts of unnatural mortality. Extend research currently underway in South Africa to Namibia (J. Shaw in litt. 2012), and repeat census in 5-10 years (J. Shaw in litt. 2016).
Text account compilers
Westrip, J., Ekstrom, J., Butchart, S., Khwaja, N., Calvert, R., Symes, A.
Hofmeyr, S., Jenkins, A., Scott, A., Scott, M., Shaw, J. & Smallie, J.
BirdLife International (2020) Species factsheet: Neotis ludwigii. Downloaded from http://www.birdlife.org on 24/11/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/11/2020.