Abstract
Wind energy development is rapidly expanding globally, as are concerns about the potential threats wind facilities pose to bird and bat populations. To date, many studies have explored the direct impacts of wind turbines on wildlife, such as wildlife-turbine collisions, but few have addressed indirect impacts, such as habitat degradation. These potentially subtle impacts can have far reaching effects on the abundance, distribution, survival, and breeding success of wildlife. We conducted a study to assess whether proximity of wind turbines to shrub-nesting birds influenced rates of nest failure associated mainly with depredation and brood parasitism by Brown-headed Cowbirds (Molothrus ater). During the primary nesting period of five passerine species, we monitored 253 active nests. We used a logistic-exposure method to model nest fate as a function of the important variables identified (including distance from turbine and brood parasitism). Our results indicate little relation between nest success and distance to turbine, with one exception, the Blue-gray Gnatcatcher (Polioptila caerule). For this passerine, we found nests closer to wind turbines had a lower probability of being brood parasitized and subsequently had higher nest success rates. We recommend future studies explore the potential implications of wind energy development on brood parasites, such as the Brown-headed Cowbird. As there is regulatory and social pressure to devise management strategies that reduce the impact of brood parasites on species of concern, any opportunities to decrease the risk of brood parasitism could be of benefit.