We used an information-theoretic approach to assess the factors affecting the reproductive success of American Oystercatchers Haematopus
palliatus on the Outer Banks of North Carolina. We evaluated survival with respect to nesting island, year, time of season, brood age, distance
to tide (m), presence of off-road vehicles and proximity of foraging habitat. The daily nest survival (mean 0.981, standard error [SE] 0.002)
was affected by year and island, and declined over the nesting season. Mammals were responsible for 54% of identified nest failures. Daily
brood survival (mean 0.981, SE 0.002) varied by island and increased non-linearly with age, with highest mortality in the seven days after
hatching. Model results indicate direct access to foraging sites has a positive effect on brood survival, whereas presence of off-road vehicles
has a negative effect. We studied chick behavior and survival using radio telemetry and direct observation and found that vehicles caused
mortality and affected behavior and resource use by oystercatcher chicks. We identified the source of mortality for 37 radio-tagged chicks.
Six (16%) were killed by vehicles, 21 (57%) by predators, and 10 (27%) by exposure and starvation. From 1995 to 2008, 25 additional
oystercatcher chicks were found dead, 13 (52%) killed by vehicles. Chicks on beaches closed to vehicles used beach and intertidal zones
more frequently than chicks on beaches open to vehicles. Chick predators included Great Horned Owls Bubo virginianus, Fish Crows
Corvus ossifragus, cats Felis catus, mink Mustela vison, raccoons Procyon lotor, and ghost crabs Ocypode albicans. The factors affecting
reproductive success differed between the incubation and chick-rearing stages. Management actions that influence chick survival will have a larger effect on total productivity than actions affecting nest survival.
