Time-activity Budgets of Yellowlegs in Managed Tidal Impoundments and Adjacent Tidal Marshes

Managed tidal impoundments are man-made wetlands constructed from natural tidal marshes and swamps with embankments and water control structures that manage water levels using tidal cycles. In South Carolina, 28,000 ha of managed tidal impoundments potentially provide important habitat for migrating and resident wildlife. The importance of traditionally-managed tidal impoundments relative to natural tidal marsh to migratory birds is poorly understood. Examining how birds allocate their time on managed tidal impoundments and natural tidal marshes can provide insight into whether birds are using these resources similarly or for different biological needs. We examined diurnal activity of greater yellowlegs (Tringa melanoleuca) and lesser yellowlegs (T. flavipes) to determine how these focal species used managed tidal impoundments and tidal marshes along the coast of South Carolina. Overall, frequency of behaviors differed between managed tidal impoundments and natural tidal marshes (F = 6.5, df = 5, 5; P = 0.031). Proportion of time yellowlegs moved (locomotion) was greater on tidal marshes (F = 19.6, df = 1, 69; P < 0.001), while proportion of time spent loafing (F = 5.7, df = 1, 69; P = 0.019) was greater on managed tidal impoundments. The greater proportion of time spent loafing on managed tidal impoundments suggests these wetlands provide body-maintenance opportunities not available in tidal marshes. Our results reveal the importance of managed tidal impoundments to migratory shorebirds within the coastal landscape. These managed habitats provide protected roosting sites and abundant, available food resources because of the controlled hydrological cycle.

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