Waterfowl Conservation in the US Prairie Pothole Region: Confronting the Complexities of Climate Change

<div><p>The Prairie Pothole Region (PPR) is the most important waterfowl production area in North America. However, waterfowl populations there are predicted to decline because of climate-related drying of wetlands. Consequently, changes in the geographic focus of PPR waterfowl conservation have been recommended, which could have long-lasting and costly impacts. We used a 40-year dataset of pond counts collected in the PPR to test hypotheses about climate-related drying. We assessed May (1974–2013) and July (1974–2003) pond numbers in 20 waterfowl survey strata to determine if trends in pond numbers were consistent with predictions of drying. We also assessed trends in precipitation and temperature for the 20 strata and developed models describing May pond numbers from 1974 through 2010 as a function of precipitation, temperature, the previous year’s pond numbers, and location. None of the 20 strata showed significant declines in May pond numbers, although seven strata showed increases over time. July pond numbers declined significantly in one stratum, and increased in seven strata. An index to hydroperiod showed significant increasing trends in three strata, and no strata had decreasing trends. Precipitation increased significantly in two strata and decreased in two from 1974 to 2010; no strata showed significant changes in temperature. The best linear model described pond numbers within all strata as a function of precipitation, temperature, the previous year’s pond numbers, and the latitude and longitude of the stratum, and explained 62% of annual variation in pond numbers. We hypothesize that direct effects of climate change on prairie pothole wetlands and waterfowl may be overshadowed by indirect effects such as intensified land use and increased pressure to drain wetlands. We recommend that an adaptive, data-driven approach be used to resolve uncertainties regarding direct and indirect effects of climate change on prairie wetlands and waterfowl, and guide future conservation efforts.</p></div

Trends in May pond numbers for seven waterfowl survey strata showing significant increases, 1974–2013.

<p>Number of May ponds (in thousands per year) increased significantly (p<0.05) in waterfowl survey strata 28, 29, 41, 46, 47, 48, and 49 of the Waterfowl Breeding Population and Habitat Survey, 1974–2013.</p

Trends in hydroperiod index for 20 waterfowl survey strata, 1974–2003.

<p>Slope of regression models of percent change in pond counts per year from May to July in 20 strata of the Waterfowl Breeding Population and Habitat Survey as a function of year (1974–2003). Large white stars indicate statistically significant trends (p<0.05); small white stars indicate 0.05</p

Trends in precipitation for 20 waterfowl survey strata, 1974–2010.

<p>Slope of trends in mean monthly total precipitation (mm per year) from 1974 to 2010 in 20 strata of the Waterfowl Breeding Population and Habitat Survey in the Prairie Pothole Region of the US and Canada. Data acquired from <a href="http://climate.geog.udel.edu/~climate/html_pages/download.htm" target="_blank">http://climate.geog.udel.edu/~climate/html_pages/download.htm</a><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100034#pone.0100034-Matsuura1" target="_blank">[32]</a>. White stars indicate statistically significant trends (p<0.05).</p

Trends in May pond numbers for 20 waterfowl survey strata, 1974–2013.

<p>Slope of regression models of May pond numbers (in thousands per year) in 20 strata of the Waterfowl Breeding Population and Habitat Survey as a function of year, 1974–2013. Large white stars indicate statistically significant trends (p<0.05); small white star indicates 0.05</p

Trends in temperature for 20 waterfowl survey strata, 1974–2010.

<p>Slope of trends in mean monthly air temperature (degrees Celsius per year) from 1974 to 2010 in 20 strata of the Waterfowl Breeding Population and Habitat Survey in the Prairie Pothole Region of the US and Canada. Data acquired from <a href="http://climate.geog.udel.edu/~climate/html_pages/download.htm" target="_blank">http://climate.geog.udel.edu/~climate/html_pages/download.htm</a><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100034#pone.0100034-Matsuura2" target="_blank">[33]</a>.</p

Trends in July pond numbers for 20 waterfowl survey strata, 1974–2003.

<p>Slope of regression models of July pond counts (in thousands per year) in 20 strata of the Waterfowl Breeding Population and Habitat Survey as a function of year, 1974–2003. Large white stars indicate statistically significant trends (p<0.05); small white stars indicate 0.05</p

Location of North American Prairie Pothole Region.

<p>Twenty survey strata from the Waterfowl Breeding Population and Habitat Survey cover most of the land area, wetlands, and waterfowl resources of the Prairie Pothole Region. The survey strata extend from 96.5°W 42.5°N in the southeast to 114.8°W 54.0°N in the northwest.</p