Synchronizing Conservation to Seasonal Wetland Hydrology and Waterbird Migration in Semi‐arid Landscapes

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In semi‐arid ecosystems, timing and availability of water is a key uncertainty associated with conservation planning for wetland‐dependent wildlife. Wetlands compose only 1–3% of these landscapes; however, large populations of migratory waterbirds rely on these wetlands to support energetically demanding life history events such as breeding and migration. Migration is considered a crucial period for birds associated with individual survival and reproductive success, yet our understanding of migration ecology remains limited. To better inform conservation planning supportive of these demands, researchers quantified synchrony of wetland flooding and waterbird migration by reconstructing bi‐monthly surface water patterns from 1984 to 2015 across 11.4 million ha of the semi‐arid Great Basin, USA. Abundance and timing of wetland flooding was modeled from 1984 to 2015 using Landsat 5 Thematic Mapper (1984–2012) and Landsat 8 Operational Land Imager (2013–2015) satellite imagery. Surface water extent was measured using constrained spectral mixture analysis (SMA). Results were then linked to seasonal migration chronologies for seven dabbling duck species.

Seasonal patterns were used in landscape planning simulations to assess efficiency in conservation strategies that aligned temporally sensitive wetland flooding and species migration. Wetland data were combined with land tenure to evaluate periodicity in waterfowl reliance on public and private lands. Migration chronologies were found to be misaligned with wetland flooding. In spring, half (43–59%) to three‐quarters (68–74%) of seasonal wetlands were flooded and available to early‐ and late‐migrating species while seasonal drying restricted wetland flooding to 13–20% of sites during fall migration. Simulations showed wetland conservation inconsiderate of temporal availability was only 67–75% efficient in meeting waterfowl habitat goals on private lands that made up ~70% of flooded wetland area in spring. Private–public wetland flooding was equivalent during fall migration.

Accounting for spatiotemporal patterns of wetland flooding is imperative to improving efficiencies linked to migratory bird conservation. Timing of public–private wetland flooding, demonstrated by our models, provides landscape context that emphasized a joint role in supporting migratory waterbird habitat. Integrated management scenarios may capitalize on public lands’ flexibility to expand fall flooding to offset seasonal drying on private lands while targeted incentive‐based conservation assures private wetland flooding in spring. Such scenarios illustrate benefits of holistic public–private wetlands management representing a forward‐looking alternative that aligns conservation with forecasts of increasing water scarcity.

Bi-monthly abundance of flooded seasonal wetlands (solid black lines) fit with polynomial regressions and overlaid with spring (Feb.–May) and fall (Sep.–Dec.) waterfowl migration chronology. Bird migrations depicted as boxplots shown as relative species abundance over time. Panels (a–f) correlate to multi-year precipitation trends used to bin wetland and migration response.

Author Name
Patrick Donnelly
Author Email