Field geospatial data were collected using a handheld GPS receiver using Wide Area Augmentation System (WAAS) correction. The spatial coordinate for the center of each site was used to obtain ortho-rectified digital aerial imagery (Appendix A).
We digitized the habitats surrounding each study site to a radius of 3.5 km using ARC GIS 9.1 (ESRI 2005). These aerial images differed temporally, representing images captured
between 1998 and 2006. Land use changes between the image date and study period were recorded by
ground-verification in June–August annually, with corrections made during the digitization process.
At the same time we also determined the specific land cover present within all areas of each landscape (Appendix B). Some locations included polygons that were not visible
from a roadway and permission to access private lands could not be obtained. These polygons were given a value of zero and were excluded from further analysis.
The area of each site that could not be identified varied from 0% to 2%.