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Wetlands throughout eastern South Dakota were surveyed (1995-97) for foraging and nesting black terns (Chlidonias niger) to evaluate local and landscape factors influencing habitat suitability. We surveyed 834 randomly selected, semipermanent, and seasonal wetlands that were stratified by physiographic domain, wetland density, and wetland surface area. A discriminant function model was used in a geographic information system (GIS) to classify habitat suitability of all semipermanent wetlands in eastern South Dakota. We calculated number of suitable, protected wetlands by combining wetlands with easement and feetitle tracts in the GIS. Black terns nested in 7.8% and foraged in an additional 17.9% of semipermanent wetlands. Significant variables in the discriminant function were wetland area, total semipermanent wetland area within the wetland complex, and grassland area in the upland matrix. Black terns were an area-dependent species that occupied large (x̄ = 18.9 ha) wetlands located within high-density wetland complexes. Black terns typically occurred in wetlands within landscapes where

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Conserving migratory birds is made especially difficult because of movement among spatially disparate locations across the annual cycle. In light of challenges presented by the scale and ecology of migratory birds, successful conservation requires integrating objectives, management, and monitoring across scales, from local management units to ecoregional and flyway administrative boundaries. We present an integrated approach using a spatially explicit energetic-based mechanistic bird migration model useful to conservation decision-making across disparate scales and locations. This model moves a Mallard-like bird (Anas platyrhynchos), through spring and fall migration as a function of caloric gains and losses across a continental-scale energy landscape. We predicted with this model that fall migration, where birds moved from breeding to wintering habitat, took a mean of 27.5 d of flight with a mean seasonal survivorship of 90.5% (95% Cl = 89.2%, 91.9%), whereas spring migration took a mean of 23.5 d of flight with mean seasonal survivorship of 93.6% (95% CI = 92.5%, 94.7%). Sensitivity analyses suggested that survival during migration was sensitive to flight speed, flight cost, the amount of energy the animal could carry, and the spatial pattern of energy availability, but generally insensitive to total energy availability per se. Nevertheless, continental patterns in the bird-use days occurred principally in relation to wetland cover and agricultural habitat in the fall. Bird-use days were highest in both spring and fall in the Mississippi Alluvial Valley and along the coast and near-shore environments of South Carolina. Spatial sensitivity analyses suggested that locations nearer to migratory endpoints were less important to survivorship; for instance, removing energy from a 1036 km2 stopover site at a time from the Atlantic Flyway suggested coastal areas between New Jersey and North Carolina, including the Chesapeake Bay and the North Carolina piedmont, are essential locations for efficient migration and increasing survivorship during spring migration but not locations in Ontario and Massachusetts. This sort of spatially explicit information may allow decision-makers to prioritize their conservation actions toward locations most influential to migratory success. Thus, this mechanistic model of avian migration provides a decision-analytic medium integrating the potential consequences of local actions to flyway-scale phenomena.

Population status and habitat use of yellow rails (Coturnicops noveboracensis), Nelson's sparrows (Ammodramus nelsoni), and Le Conte's sparrows (A. leconteii) are poorly known, so standardized surveys of these species are needed to inform conservation planning and management. A protocol for monitoring secretive marsh birds exists; however, these species regularly call at night and may be missed during early morning surveys. We tested the effectiveness of autonomous recording units (hereafter, recording units) to survey these species by analyzing recorded vocalizations using bioacoustics software. We deployed 22 recording units at 54 sites in northern Minnesota and eastern North Dakota, USA, and conducted traditional broadcast surveys during May-June, 2010 and 2011. We compared detection probabilities between recording units and standard monitoring protocols using robust-design occupancy models. On average, recording units detected 0.59 (SE ¼ 0.11) fewer Le Conte's sparrows, 0.76 (SE ¼ 0.15) fewer Nelson's sparrows, and 1.01 (SE ¼ 0.14) fewer yellow rails per survey than were detected using the standard protocol. Detection probabilities using the standard protocol averaged 0.95 (yellow rail; 95% CI ¼ 0.86-0.98), 0.93 (Le Conte's sparrow; 95% CI ¼ 0.78-0.98), and 0.89 (Nelson's sparrow; 95% CI ¼ 0.56-0.98), but averaged 0.71 (yellow rail; 95% CI ¼ 0.56-0.83), 0.61 (Le Conte's sparrow; 95% CI ¼ 0.42-0.78), and 0.51 (Nelson's sparrow; 95% CI ¼ 0.19-0.82) using recording units. Reduced detection by recording units was likely due to the ability of human listeners to identify birds calling at greater distances. Recording units may be effective for surveying nocturnal secretive marsh birds if investigators correct for differential detectability. Reduced detectability may be outweighed by the increased spatial and temporal coverage feasible with recording units. Ó 2015 The Wildlife Society.