Collision with overhead wires can result in significant avian mortality and is of conservation concern for many larger bird species. To date, little progress has been made in understanding the scale and demographic impacts of this problem, or in developing effective mitigation measures. In this thesis I used various approaches to investigate power line collision mortality of the large terrestrial avifauna of the vast semi-arid Karoo, South Africa, with particular reference to Ludwig's Bustard Neotis ludwigii. This little-known species is endemic to the arid western parts of southern Africa and is thought to be both partially migrant and nomadic in response to rainfall. It was listed as globally Endangered on the IUCN Red List in 2010 as a result of potentially unsustainable collision mortality.