Evaluating the Responses of Least Terns, Common Terns, Black Skimmers, and Gull-billed Terns to Military and Civilian Aircraft and to Human Recreation at Cape Lookout National Seashore, North Carolina
Hillman, Matthew Dean
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Due to variability in aircraft overflight type and associated animal responses, there is a lack of consensus on the effects of overflights on wildlife populations. My objectives were to 1) evaluate the potential impacts that reduced-altitude tactical speed military aircraft might generate on nesting colonial waterbirds, and to place any impacts in the context of other human events, 2) a) identify key least tern (Sternula antillarum) demographic drivers, b) evaluate the accuracy of assigning nest fates without using remote cameras, and c) assess the effects of camera-monitoring on nest survival, and 3) evaluate the agreement between two techniques used to estimate peak least tern breeding abundance. I conducted my study at Cape Lookout National Seashore, North Carolina from May-August 2010-2012. I surveyed colonies once every 3-5 days and deployed audio recorders and time-lapse cameras at individual nests in 9 colonies. Birds did not incubate less or engage in alert behaviors during overflights compared with control periods. Least terns reduced incubation by a mean of 12% when pedestrians were observed near nests (S = -2.2, p = 0.04). Demographic effects from overflights or recreation are unlikely given the patterns of use in this study. Least tern demographic rates were driven by raccoon depredation. Cameras reduced daily nest survival (SE) from 0.85 (0.06) to 0.79 (0.08). However, cameras also decreased the frequency of unknown or misclassified nest fates by > 30%. Incubating adult counts were effective in assessing peak nest abundance at colonies where topography did not impede scanning from the perimeter.
- Masters Theses