Using radar technology to assess visual monitoring accuracy of Cape Vulture movements

South Africa’s expanding wind energy industry is providing much needed alleviation from an ongoing energy crisis. Its development, however, does bear environmental repercussions, which most notably include its impact on birds. Collision risks, habitat loss, and barrier effects are amongst the threats, which require effective mitigation efforts. Avian radar systems have vastly enhanced these efforts and one such system was applied in this study to assess the accuracy of the generally more employed visual monitoring efforts, with a focus on Cape Vultures Gyps coprotheres in the Eastern Cape Province. This, to the best of our knowledge, also marks the first study of this nature on the African continent. Paired observations returned substantial spatial disparity between radar and visual Cape Vulture observations. They also revealed strong relationships between altitudinal misjudgement and height of the target, as well as distance of the target from the observer. Cape Vulture flight and foraging behaviour makes it a challenging observer target. The results of this study suggest that radar technology can be effectively employed at sensitive sites for Cape Vulture movement assessments at wind farms.