Wetland basins in the Prairie Pothole Region of the U.S. are commonly modified by excavation (e.g., roadside ditches, stock dugouts), partial drainage, and diking. The authors used data collected on thirty-eight 40-km2 plots in North Dakota to examine the distribution of modified basins relative to roadside transects and their use by five species of dabbling ducks in 1995. Semipermanent basins had greater use by mallards and northern pintails when they were partially drained than when they were excavated or unmodified; pintails also had greater use of partially drained seasonal basins. Duck numbers determined from standard 400-m-wide roadside transects do not appear to be biased relative to the larger landscape; however, pond counts derived from such transects were biased. Correlations of duck numbers to pond counts that exclude ditches or temporary basins would poorly reflect the response of ducks to available water.
Additional publication details
Differences in distribution of modified basins and ducks relative to roadside transects