South Africa?s bustards are in trouble, with six of the country?s ten species listed in the South African Red Data Book. ?They are threatened by a variety of factors?, says Mark Anderson, executive director of Bird- Life South Africa ??with some of the most important threats being habitat destruction and power-line mortalities?.
BirdLife South Africa is concerned about the precarious conservation status of the country?s bustards and korhaans. At a workshop in Johannesburg in May, the status, threats and necessary conservation measures relevant to these birds were discussed by the country?s bustard experts.
Populations of Ludwig?s bustard and Denham?s bustard are probably in decline due to a single mortality factor, collisions with the cables of power-lines. ?These birds fly in groups during low light conditions and due to their limited manoeuvrability are not able to avoid electricity cables in their flight path?, says Jon Smallie, manager of the Endangered Wildlife Trust?s (EWT) Wildlife Energy Interaction Group (WEIG) and the Eskom-EWT Strategic Partnership. Studies by Anderson and the University of Cape Town?s Dr Andrew Jenkins, have found that on average across six patrolled sites, about one Ludwig?s bustard collides per kilometre of power-line per year at these sites.
There are approximately 16,000 km of transmission (>132000volts) power-lines crisscrossing the Karoo indicating the potential severity of this problem. The Eskom- EWT Partnership?s Central Incident Register documents no less than 265 confirmed Ludwig?s bustard mortalities from power-lines. In response, Eskom is currently funding research into bustard collision rates, movement patterns and visual acuity ? all critical aspects if we are to mitigate this threat.
According to David Allan, ornithologist at the Durban Natural Science Museum and a world authority on the biology of bustards, ?The global population of Ludwig?s bustard has been estimated to only number between 56,000 and 81,000 individuals. The thought that we could be potentially losing them at a rate of over 10,000 birds killed annually by this factor alone is terrifying?.
The blue korhaan, which mainly inhabits grasslands in the central and eastern regions of South Africa, is severely threatened by afforestation, crop farming, overgrasing, burning, urbanisation and mining. Analyses of information from the Coordinated Avifaunal Roadcount Project (CAR) suggest that this korhaan has ??declined in both numbers and range during recent years?, stated Donella Young, the CAR coordinator at the University of Cape Town?s Animal Demography Unit. The blue korhaan is only found in South Africa and marginally in western Lesotho, so we have an important obligation to protect this localised species.
The white-bellied korhaan, another species that is restricted to the grasslands and open thornveld, is listed as vulnerable in the South African Red Data Book. It prefers tall, undisturbed grassland, and is thus threatened by human population pressure and inappropriate farm management. The white-bellied korhaan is also found in central, west and east Africa, but there is some debate about whether the South African population is a separate species (Barrow?s korhaan). If genetically distinct, there is even more pressure on South African conservationists to attend to the numerous threats which are impacting on this threatened species.
It was decided at the bustard workshop, which was made possible through funding from E. Oppenheimer and Son, that a bustard working group would be formed under the auspices of BirdLife South Africa. The group will have several aims, but will focus, at least initially, on disseminating information about bustards to the relevant authorities and stakeholders, prioritizing research needs, and determining urgent conservation interventions.