Synchronizing conservation to seasonal wetland hydrology and waterbird migration in semi-arid landscapes

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, we 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. Results were then linked to seasonal migration chronologies for seven dabbling ducks 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. We found migration chronologies misaligned with wetland flooding. In spring, half (4359%) to three-quarters (68-74%) of seasonal wetlands were flooded and available to early-and latemigrating 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 similar to 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.