Monitoring the Effects of Climate Change on Waterfowl Abundance in the Mississippi Alluvial Valley: Optimizing Sampling Efficacy and Efficiency

Winter waterfowl surveys have been conducted across much of the United States since 1935. Aerial surveys conducted using stratified random sampling have the advantages of extensive coverage, increased accuracy, and the ability to calculate the variance of estimates. A statistically robust stratified random sampling design for aerial surveys of mallards in the Mississippi Alluvial Valley (MAV) was developed in the late 1980s and early 1990s; surveys based on this sampling design have been conducted by the Mississippi Department of Wildlife, Fisheries, and Parks (MDWFP) in the Mississippi MAV since 2005 and by the Arkansas Game and Fish Commission (AGFC) in the Arkansas MAV since 2009. However, changes in land use since the survey was designed may have made modifications of the original design necessary. We refined strata boundaries in Arkansas using watersheds as a guide in determining strata boundaries and surveyed the Arkansas MAV four times during winter 2011-2012 using this modified design. To evaluate the performance of this new design we compared three sampling designs: 1) simple random, 2) expert opinion-based strata (original design), and 3) watershed-based strata (new design). For each of the four survey periods and each of the three sampling designs, we calculated %CV of the estimated number of mallards and total ducks by bootstrapping the surveyed transects in each survey period 10,000 times each under each of the three sampling designs. The %CV for all ducks and mallards was lower under the new watershed-based stratified random sample than under either the simple random or expert-based designs during all four survey periods. The watershed-based sampling design also estimates waterfowl abundance at a finer resolution using biologically meaningful strata.

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Maintainer Brent Frakes
Last Updated July 29, 2019, 03:42 (CDT)
Created July 29, 2019, 03:42 (CDT)