Human disturbance and predation may contribute to low reproductive success for American oystercatchers at Cumberland Island National Seashore (CINS), Georgia; however, no recent studies have focused on identification of causes of egg and hatchling losses. We used continuous video monitoring to document reproductive success of American Oystercatchers and identify causes of nest failure at CINS, from 2003-2004. We used the modified Mayfield method and the program CONTRAST to determine and compare survival of eggs and nestlings from 32 nest attempts during two seasons. Nine attempts were successful, fledging 15 chicks. Daily survival was 0.9732 (95% CI = 0.9598 - 0.9866) for 2003,0.9846 (95% CI = 0.9740 - 0.9952) for 2004, and 0.9787 (95% CI =0.9701 0.9873) for combined years. Daily survival of clutches was greater on the North end than on the South end of the island (X2 = 7.211, df= 1, P = 0.0072). We documented 18 of 20 nest failures during the egg stage. Because of chick mobility, we only documented 1 of 8 chick losses. We identified 3 egg predators: raccoon (Procyon lotor, n = 9), bobcat (Lynx rufus, n = 3), and American crow (Corvus brachyrhynchos, n = I). The chick was depredated by ghost crab (Ocypode quadata). Other causes of nest failure included tidal overwash (n = 1), horse trampling (n = 1), abandonment (n = 2), and destruction by a small child (n = 1). Predator control may be an effective means of increasing reproductive success on the South end. The North end may serve as an important source of fledglings in Georgia and should be preserved.
Additional Publication Details
Fate and productivity of beach nesting American Oystercatchers, Cumberland Island National Seashore, Georgia
Wilson Ornithological Society and Association of Field Ornithologists Joint Meeting, April 21-24, Beltsville, Maryland. Abstracts