This data release contains breeding-bird densities in native mixed-grass prairie collected from 2003 to 2012 at and adjacent to wind farms in North and South Dakota, USA, for one year prior to turbine construction and several years post-construction. One dataset contains breeding-bird densities per 100 ha by distance from turbines for categories of 0-100 m, 100-200 m, 200-300 m, and greater than 300 m from turbines and for reference (i.e., control) sites. A second dataset contains breeding-bird density overall for turbine and reference sites, without the distance-category breakdown. A third dataset contains measurements that characterize average vegetation structural measurements on each study plot. This data release supports the following manuscript: Shaffer, J.A., and D. A. Buhl. 2016. Effects of wind-energy facilities on breeding grassland bird distributions. Conservation Biology 30:59-71. doi:10.1111/cobi.12569.