Browsing by Author "Becker, Frowin Klaus"
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- ItemOptimising the use of visual and radar observations for the mitigation of wind energy related impacts on Cape Vultures (Gyps coprotheres) in the Eastern Cape Province(Stellenbosch : Stellenbosch University, 2016-03) Becker, Frowin Klaus; Leslie, Alison J.; Millikin, Rhonda L.; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.ENGLISH ABSTRACT: Being one of the leading global renewable energy investors over the last few years, South Africa’s energy sector is undergoing a rapid transformation. This transformation has been driven by the Renewable Energy Independent Power Producers Procurement Programme (REIPPPP) – a competitive bidding process, which has already concluded four bidding windows since 2011. Wind energy has comprised the bulk of the approved projects, thus far. Its accelerated development, however, poses a threat to the country’s airborne wildlife. Birds have been amongst the avifauna, most affected by wind energy facilities (WEF), both directly and indirectly. These impacts include collision-induced mortalities, habitat loss, costly avoidance behaviour, and barrier effects, which have been well documented in Europe and the United States. In response to such impending risks, South Africa’s environmental sector has drawn up a set of guidelines for baseline studies, pre-construction, and post-construction monitoring of birds. Two of the recommended monitoring techniques are direct or visual observations, and radar observation, which formed the foundation of this study. Due to its morphology, phenology and flight behaviour, the Cape Vulture (Gyps coprotheres) is considered as particularly vulnerable to WEFs, and has recently been deemed ‘endangered’, both locally and globally. Considering the species’ somewhat fragile status, using it as the primary subject, only added more significance to the study. The aims were to (1) assess the accuracy of visual observations, and (2) investigate activity patterns amongst Cape Vultures in the Eastern Cape Province, using a marine surveillance radar (EchoTrack Inc.). The proposed Umtathi Emonyeni WEF near Komga (-32.577°, 27.888°) in the Eastern Cape Province, served as the study site. Here, three radar placement sites were established. Vantage point (VP) and radar observations were conducted simultaneously from October 2014 to June 2015. A total of five replicates were completed in that time, one consisting of 12 days. Four days were spent at each placement site. Visually assessed targets were plotted using a cross-platform Geographical Information System (GIS), which allowed for the recording of coordinates. Parameters captured by the radar included latitudinal and longitudinal coordinates, flight height, reflectivity (size), and the airspeed of each target. Using customised EchoTrack software, visual and radar tracks were matched with a certain degree of confidence, depending on temporal, spatial and directional margins. A total of 66.4% of all visual observations were matched with corresponding radar tracks. The mean difference in time and distance, between those tracks, was 108.8s and 262.7m, respectively. Those margins were highly significant between Cape Vultures and other priority species. The dataset also indicated a significant positive relationship between both degree of inaccuracy and the distance of the target from the radar, as well as the degree of inaccuracy and the target’s height. Using the visually verified Cape Vulture radar tracks, target airspeed and size were used to distinguish the remaining unverified dataset from other bird tracks. Movement frequency (observations/hour), climbing rate (m/s), and flight height all exhibited similar patterns, with peaks being reached during the middle of the day. Trends in movement frequencies were valid for both visual and radar observations. Results presented here highlight the inconsistencies that govern visual monitoring. They also demonstrate the broad practical uses of avian radar systems. Implementing a comprehensive pre-construction monitoring regime is of great value to both the developers and bird conservationists. Collecting high-quality data vastly improves the reliability of the mitigation strategies that are put in place, and ensures that impacts are efficiently minimised. This also benefits developers as minimal impacts decrease the probability of costly compensations. While radar’s application is limited to bird movements, and still requires augmentation through visual observations, the quality of data produced adds significant value to both research and management decision-making. Obtaining data of such high quality is even more valuable for the conservation of endangered species, like the Cape Vulture.