Effects of Wind Developments on Grassland Birdsin the Northern Great Plains Jill A. Shaffer Douglas H. Johnson Deb A. Buhl Northern Prairie Wildlife Research Center U.S. Department of the Interior U.S. Geological Survey
Do wind turbines in native prairie affect the presence and abundance of grassland birds?
If so, which species are affected? If so, how far does the turbine exert an influence?
Wind Developments of Interest North Dakota Oliver Co. Dickey Co. McPherson Co. South Dakota Hyde Co. Hand Co.
Wind Developments of Interest • Acciona Energy • 120 1.5-MW wind turbines • Dickey County, ND & • McPherson County, SD • BP Alternative Energy • 10 2.5-MW wind turbines • Hand County, SD • NextEra Energy Oliver I • 22 2.3-MW wind turbines Oliver County, ND • NextEra Energy South Dakota Wind Energy Center • 27 1.5-MW wind turbines • Hyde County, SD
Our Approach Aim: Identify patterns in avoidance of wind turbines by grassland-nesting birds Habitat: Mixed-grass prairie in ND and SD Methods: Before-After Control-Impact (BACI) Map bird locations, Delineate major habitat types Compare observed distances to expected distances to identify patterns in avoidance
Before-After, Control-Impact Before: Conduct bird surveys in areas where wind turbines will be constructed, before they are constructed After: Conduct surveys in the same locations in the years after construction
BEFORE A site near Highmore, SD, where we censused birds prior to turbine construction AFTER This is the same site post-construction, where we censused birds post-construction.
Before-After, Control-Impact Control: Conduct surveys on non-turbine sites, matched for topography, habitat, and land use Impact: Conduct surveys on turbine sites
The first panel shows a control site on the Highmore, SD, site and, in the second panel, the impact area. CONTROL IMPACT
This shows NEE Energy’s (formerly FPL) South Dakota site in Hyde County. The black outlines are study plots; orange outlines are reference (control) areas. Yellow crosses represent actual turbine locations.
The black circles are the locations of fiberglass fence posts and survey markers. Bird surveys are conducted throughout the entire area within this grid system.
Bird Census byTotal-area Survey Census grid: Maximize the area around a turbine that is censused Record locations of individual birds Be able to determine distance of birds from nearest turbine
This a photo of an actual study plot on the Hyde Co., SD, site. We attempt to set up grids within an area that is ½ mile on all sides of the turbines, shown here within the red boundary. Exceptions to the ½-mile rule are areas where land use changes sooner from native prairie or where we don’t have access permission. Birds are recorded 50 m on either side of the pathway that the observers walk. We conduct two to four surveys from mid-May to late June.
Results of one bird survey Results of one survey This is an example of the results of one survey. These results are 2003, pre-construction (yellow crosses thus represent where turbines will be built). By assigning spatial coordinates to every bird location, we can determine the distance of each bird observation from the nearest turbine.
Results of four surveys of Grasshopper Sparrows Here we have extracted the results of four surveys for just one species, the Grasshopper Sparrow. You can detect a paucity of GRSP in the upper corner of the plot and around the wetlands.
By delineating general habitat types, in this case prairie-dog towns and wetlands, it was easy to discern that Grasshopper Sparrows generally avoided these habitats. We remove this area from the total area deemed suitable habitat for the particular species under analysis. Remember that this depicts a pre-construction year. In a post-construction year, we further remove the area of previously suitable habitat that was impacted by construction, so would remove, at a minimum, the turbine pads.
After removing unsuitable habitat for the focal species, we placed 10,000 random points in the area of suitable habitat.
We placed 10,000 random points in the area of suitable habitat for all study plots.
Statistical Analysis We compared the number of sightings of birds at various distances from wind turbines to the number expected if turbines had no effect.
South Dakota Wind Energy Center We calculated the distance from each observed bird location to the nearest turbine and the distance of each random point to the nearest turbine. Those distances were then assigned to one of the following 15 distance categories at the South Dakota Wind Energy Center.
Oliver I Wind Facility, North Dakota The distances from each observed bird location to the nearest turbine and the distance of each random point to the nearest turbine were assigned to one of the following 21 distance categories at the Oliver I wind facility, which had larger study plots.
Example of Statistical Analysis using 2007 data for Grasshopper Sparrow from the Oliver I Wind Facility Observed vs. Expected Tally at d = 50 Tally at d = 100 We compared the observed distribution of minimum distances to the expected distances under the assumption of no-displacement effect. For every d (where d = 50, 100, 150, …, 1000 m), the number of birds within distance d of a wind generator, as well as the number beyond d,were tallied.
Likelihood Ratio Statistic Largest g2 indicates avoidance occurred up to 150 m The observed distribution for every d was compared to the expected distribution using a likelihood ratio test (g2). The d with the highest ratio was considered the distance up to which attraction or avoidance was occurring.
Contact Information: Jill Shaffer or Douglas Johnson USGS Northern Prairie Wildlife Research Center Shaffer: 701-253-5547; firstname.lastname@example.org Johnson: 612-624-4716; Douglas_H_Johnson@usgs.gov