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

The hydroperiod (i.e., the length of time ponded water is present) of prairie potholes is sensitive to climate change. Because snowmelt runoff is the largest contributor to ponded water amounts, a seasonal change in precipitation timing, even when annual amounts are unchanged, can affect wetland hydroperiod. We observed a change in precipitation timing in the Alberta Prairie Pothole Region from 2014 to 2015, though cumulative precipitation amounts were near equivalent. 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 findings suggest a change in precipitation timing occurred in 2015 (i.e., delayed-precipitation year), which could be tied to a decline in wetland hydroperiod. Wetlands in the delayed-precipitation year were dominated by upland birds and drought-adapted aquatic macroinvertebrates. There was no change in the community composition of plants, and we hypothesize that this may be explained by their ability to use energy stored from the previous year to survive this one-year change in their growing season. We suspect that consecutive declines in hydroperiod year-to-year could shift vegetation communities to being dominated by wet meadow or terrestrial plants; this will ultimately lead to a further reduction of waterbird habitat in the northern PPR – the last refuge for this guild in the PPR.