2000

Ground wires associated with high voltage power transmission lines have been identified as a source of mortality for numerous avian species. Collisions between birds and power lines have been studied by numerous researchers to better understand the factors that are involved in these collisions and the effectiveness of mitigation measures. There are three chapter included in this thesis; the first being a review of avian power line collisions that includes a literature review of collision incidents, factors that influence
collisions, and methods of avoiding strikes.

The second chapter discusses the relationships between wing morphology and behavioral responses to unmarked transmission lines. This research was conducted a t the Cinergy-PSI Gibson County Power Generating Station located in Gibson County, Indiana. This site was a secondary focal area to the main research location in Knox County, Indiana. Bird flight observations were conducted along with corresponding ground searches to determine the species specific reactions of birds to the power lines. Birds most likely to react to power
lines were those that approached the lines at a height between the conductor and ground wires, and a significant difference was found in the reaction distances between flocks >10 birdsand single birds.

The third chapter consists ofthe results from the main focus of the study conducted in Knox County, Indiana, in which the effectiveness of groundwire marking devices was tested. This research was conducted over two consecutivewinter field seasons to include a control year and a treatment year. The treatment field season consisted of the use of two ground wire marking devices, Bird Flight Diverters (BFD) and Swan Flight Diverters (SFD), both in yellow and gray, tested sequentially. During each field season, estimates were calculated for research biases (i.e., search, removal, habitat, and crippling biases), which, in combination with ground search data, were subsequently used to estimate the total number of collisions with power lines. The estimated total number of collisions for marked lines was reduced by 51.4% compared to the same spans before marking. The BFDs reduced collision mortality by 73.3%, and the SFDs reduced collision mortality by 37.5%.