Limited shifts in the distribution of migratory bird breeding habitat density in response to future changes in climate

Abstract

Grasslands, and the depressional wetlands that exist throughout them, are endangered ecosystems that face both climate and land‐use change pressures. Tens of millions of dollars are invested annually to manage the existing fragments of these ecosystems to serve as critical breeding habitat for migratory birds. The North American Prairie Pothole Region (PPR) contains millions of depressional wetlands that produce between 50% and 80% of the continent’s waterfowl population. Previous modeling efforts suggested that climate change would result in a shift of suitable waterfowl breeding habitat from the central to the southeast portion of the PPR, an area where over half of the depressional wetlands have been drained. The implications of these projections suggest a massive investment in wetland restoration in the southeastern PPR would be needed to sustain waterfowl populations at harvestable levels. We revisited these modeled results indicating how future climate may impact the distribution of waterfowl‐breeding habitat using up‐to‐date climate model projections and a newly developed model for simulating prairie‐pothole wetland hydrology. We also presented changes to the number of “May ponds,” a metric used by the U.S. Fish and Wildlife Service to estimate waterfowl breeding populations and establish harvest regulations. Based on the output of 32 climate models and two emission scenarios, we found no evidence that the distribution of May ponds would shift in the future. However, our results projected a 12% decrease to 1% increase in May pond numbers when comparing the most recent climate period (1989–2018) to the end of the 21st century (2070–2099). When combined, our results suggest areas in the PPR that currently support the highest densities of intact wetland basins, and thus support the largest numbers of breeding‐duck pairs, will likely also be the places most critical to maintaining continental waterfowl populations in an uncertain future.

Unraveling a century of global change impacts on winter bird distributions in the eastern United States

“…While previous work has linked multidirectional changes with precipitation variables (Bateman et al, 2016; VanDerWal et al, 2013), we hypothesize that this result could also be a function of climate niche expansion (Ralston et al, 2017) by species with increasing population trends in both groups (Meehan et al, 2021), including Double‐crested Cormorant ( Phalacrocorax auritus ; waterbird group) as well as several ducks and geese in the waterfowl group (Rosenberg et al, 2019; see Tables S2–S10 for CBC occurrence trends). These results, coupled with the high relative importance of both temporal and LULC processes in explaining model deviance (Figure 4), are consistent with previous findings that waterfowl and waterbirds are particularly responsive to decadal fluctuations in wetland availability and/or inundation (e.g., McKenna et al, 2021). Given the relative scarcity of wetlands across the study area (Figure S1), we suggest that conservation programs aimed at restoring wetland habitats on private lands (e.g., National Resource Conservation Service's Wetland Reserve Program, U.S.…”

“…Fish and Wildlife Service's Partners for Fish and Wildlife Program) become an essential adaptation strategy for ensuring that wetland‐reliant species are able to locate appropriate habitats as climate variability becomes more extreme (Benson et al, 2018). These efforts are particularly important in regions like the Prairie Potholes, which support high waterfowl densities despite declines in occurrence, and are projected to lose critical wetland basins under climate change scenarios (McKenna et al, 2021).…”

Large increases in methane emissions expected from North America’s largest wetland complex

“…SSP2-4.5 and SSP5-8.5 represent “middle of the road” (moderate warming, ~1.7°C PPR) and “intensive fossil fueled” (severe warming, ~2.7°C PPR) emission trajectories, respectively ( 54 ). While ESMs have relatively high confidence and agreement on future temperature predictions, there is much greater uncertainty and disagreement of future precipitation patterns among ESMs in the PPR and elsewhere ( 55 ). Moreover, policy and land management decisions in both the United States and Canada will influence the relative amounts of wetland drainage, conservation, and restoration ( 56 ).…”

“…Unlike the clear consensus among ESMs in the directionality of future atmospheric temperature warming, there is much less agreement among forecasts of future precipitation in the PPR. Future mean annual precipitation change in the PPR by the end of the 21st century could range from −19 to +33% when compared to 1990 to 2020 normals ( 55 ). Therefore, to simulate wetland extent of future scenarios, we used DSWE and NDVI rasters from 1991 and 2011 to represent bookends of the potential range in wetland extent from dry to wet, respectively, in the PPR.…”

Climate and Land Use Driven Ecosystem Homogenization in the Prairie Pothole Region

“…However, there is still much uncertainty as to the magnitude of seasonal and annual temperature and precipitation changes in the PPR, and how wetland ecosystems will respond to these changes [144][145][146]. One commonality in future climate predictions is that temperatures will continue to increase, and average ponded-wetland densities will decrease [145,147]. With increases in temperatures come increases in evaporation rates of wetland ponds.…”