FACTORS INFLUENCING REPRODUCTIVE SUCCESS OF NEAR-SHORE SEABIRDS IN CAPE ROMAIN NATIONAL WILDLIFE REFUGE, SOUTH CAROLINA

Little is known about the reproductive success of Least Terns (Sternula antillarum) and Black Skimmers (Rynchops niger) along the coast of South Carolina. It appears reproductive success of both species may be limited by a variety of ecological stressors. To provide baseline measurements of reproductive success of Least Terns and Black Skimmers in South Carolina, and to assess factors which may influence nest success of both species, 257 Least Tern and 347 Black Skimmer nests were monitored at four colony sites within Cape Romain National Wildlife Refuge, 2009-2010. Nest success was highly variable among colony sites and years for both species. Apparent nest success ranged from 0 - 97% for Least Terns and 0 - 81% for Black Skimmers. Variation in daily nest survival of Least Terns was strongly related to colony site, year, and predation risk. For Black Skimmers, daily nest survival was best explained by a combination of various factors at multiple scales including tide height, predation risk, clutch size, and colony site. Predation and overwash were the principle causes of nest loss, collectively accounting for 65% of nest loss for both species. Nest predators included American mink (Neovison vison), Black Vulture (Coragyps atratus), Great Horned Owl (Bubo virginianus), and Laughing Gull (Larus atricilla). Estimates of productivity and age-specific survival are needed to determine if these highly variable rates of nest success of Least Terns and Black Skimmers can support local populations