Climate change causes declines and greater extremes in wetland inundation in a region important for wetland birds

Wetland ecosystems are vital for maintaining global biodiversity, as they
provide important stopover sites for many species of migrating
wetland-associated birds. However, because weather determines their
hydrologic cycles, wetlands are highly vulnerable to the effects of
climate change. Although changes in temperature and precipitation
resulting from climate change are expected to reduce inundation of
wetlands, few efforts have been made to quantify how these changes will
influence availability of stopover sites for migratory wetland birds.
Additionally, few studies have evaluated how climate change will influence
inter-annual variability or the frequency of extremes in wetland
availability. For spring and fall bird migration in 7 ecoregions in the
south-central Great Plains of North America, we developed predictive
models associating abundance of inundated wetlands with a suite of weather
and landcover variables. We then used these models to generate predictions
of wetland inundation at the end of the century (2069–2099) under future
climate change scenarios. Climate models predicted the average number of
inundated wetlands will likely decline during both spring and fall
migration periods, with declines being greatest in the eastern ecoregions
of the Great Plains. However, the magnitude of predicted declines varied
considerably across climate models and ecoregions, with uncertainty among
climate models being greatest in the High Plains ecoregion. Most
ecoregions also were predicted to experience more-frequent extremely dry
years (i.e., years with extremely low wetland abundances), but the
projected change in inter-annual variability of wetland inundation was
relatively small and varied across ecoregions and seasons. Because the
south-central Great Plains represents an important link along the
migratory routes of many wetland-dependent avian species, future declines
in wetland inundation and more frequent periods of only a few wetlands
being inundated. resulting in an uncertain future for migratory birds as
they experience reduced availability of wetland stopover habitat across
their migration pathways.