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Ludwig’s Bustard became a globally Endangered species in 2010 due to increasing collisions with power lines and wind farms. In an attempt to reduce the mortality, their movements are now being tracked using Eskom-funded GPS satellite transmitters.
By Jessica Shaw
Ludwig’s Bustards are large, stately birds of the semi-arid Karoo and Namib, and are found only in southern Africa. Unfortunately, everything about them makes them susceptible to collisions with overhead lines. These birds have limited frontal vision, often fly together and in low light conditions, and are too big to change direction quickly when faced with unexpected obstacles in flight. They make a seasonal migration to the winter rainfall area of South Africa, but also move less predictably in response to local rainfall in their dry environment. With over 10% of the population estimated to die in collisions every year, Ludwig’s Bustard became a globally Endangered species in 2010. The power grid in their remote homeland is extensive and expanding, with tens of thousands of kilometres of power line already in place, and wind farms set to spring up across their range. In light of the enormous and immediate threat posed by collisions to this long-lived bird, the Ludwig’s Bustard Project was initiated at the Percy FitzPatrick Institute to investigate the impacts of this unnatural mortality, and to find effective ways to mitigate it.
Since 2009, power line surveys have been conducted on foot and from our Mazda Wildlife Fund 4x4 bakkie across the Karoo, and are set to start in Namibia later this year. So far, these surveys have confirmed that both high and low voltage lines kill substantial numbers of Ludwig’s Bustards, with Blue Cranes and Kori Bustards also dying worryingly often. The collision rates vary across the year as Ludwig’s Bustards move around the Karoo, so clarifying these movements is a key part of our project – if we know more about where these birds are going and why, we might be able to predict which lines are the most problematic. The best way to generate high-quality spatial data is through satellite telemetry, and after many, many weeks in the field trying to catch these exceptionally wary birds, we have now successfully fitted 8 male Ludwig’s Bustards with Eskom-funded GPS satellite transmitters. Almost two years after our first deployments, we have information on their movements that previously were only suspected, as well as a wealth of data on their day-to-day habits, their roost and foraging site preferences, and crucially, how much time they spend in the vicinity of power lines.
More recently, we teamed up with the Endangered Wildlife Trust and Eskom to set up one of the biggest line marking experiments ever conducted. Line marking is the standard mitigation method used to lower collision rates in South Africa and worldwide: markers are hung on the line to make them more visible to birds. However, there is currently no conclusive evidence that this is effective for birds like Ludwig’s Bustards and Blue Cranes, so our experiment is testing the two markers commonly used in South Africa. We check the 70 km of line covered by the experiment every 6 weeks. Initial indications are that the markers seem to be working for cranes, and although it’s too early to say for Ludwig’s Bustards, we hope for more answers by the end of the year.