WIND TURBINES DO NOT NEGATIVELY AFFECT NEST SUCCESS IN THE DICKCISSEL (SPIZA AMERICANA)

Proliferation of wind energy across the Great Plains of the United States has the potential to negatively affect many grassland birds through displacement, avoidance, or changes in nesting ecology. This is troublesome because grassland birds have had the highest average annual rate of decline over the past several decades. We studied the potential indirect effects of wind turbines on nesting success in Dickcissels (Spiza americana) at a utility-scale wind farm in north-central Texas in 2010 and 2011. We monitored 195 nests and found that proximity to a wind turbine did not affect nest density or nest-site characteristics. We used an information theoretic approach with logistic exposure modeling to identify the most likely models of nest fate. Nest initiation day and distance to wind turbine were the most important predictors of nest success. Proximity to a wind turbine did not reduce nest success. Furthermore, the daily survival rates at our site were within the range documented for Dickcissels at other sites without wind-energy developments. For the monitored nests, snake predation was the greatest source of nest failure and depredated nests were closer to woodland edges than to wind turbines. This maybe because wind turbines were farther away from wooded edges. On the other hand, we cannot rule out the possibility that wind-energy development influenced predator behavior and activity, and this may warrant additional investigation. We recommend further research into the breeding ecology of a diverse selection of grassland species to fully assess the indirect effects of wind-energy development on grassland birds. Received 6 October 2012, accepted 4 April 2013.