Consistent but Delayed Timing of Precipitation Affects Community Composition of Prairie Pothole Birds and Aquatic Macroinvertebrates, but not Wetland Plants

Abstract

The hydroperiod (i.e., the length of time ponded water is present) of prairie potholes largely depend on cumulative precipitation amounts, which are sensitive to climate change. Snowmelt runoff is the largest contributor to ponded water amounts. Thus, a change in precipitation timing -where a decline in winter/spring amounts is matched with an equivalent increase in summer amounts -can affect wetland hydroperiod. Between 2014 and 2015, cumulative precipitation amounts were near equivalent; however, precipitation amounts in 2015 were higher in the summer and lower in early spring when compared to climate normals. We sought to understand whether this change in precipitation timing could result in 1) a decline in wetland hydroperiod and 2) a change in the community composition of birds, aquatic macroinvertebrates and plants. Our ndings suggest a change in precipitation timing in 2015 could be tied to a decline in wetland hydroperiod. Additionally, bird and aquatic macroinvertebrate community composition changed between years. For birds, wetlands were dominated by wetland-dependent bird taxa in 2014, but by upland birds in 2015. In 2015, wetlands supported a nested subset of the macroinvertebrates present in 2014, and these were families that were either able to reproduce outside wetlands or could suspend metabolic activities under drought conditions. There was no change in the community composition of plants, and we hypothesize that this may be explained by their ability to utilize rhizomes from the previous year to survive this one-year change in their growing season.