Ecological interactions on islands often vary from interactions characteristic of mainland ecosystems. When compared to the mainland, islands typically exhibit higher population density, less interspecific interactions, and lower species/predator richness. However, the degree of difference between the mainland and neighboring island is typically influenced by island size and isolation since these factors are particularly relevant to rates of colonization and migration. Our objective for this project was to assess how island size and isolation influenced the rate of nest predation on islands in Lake Lanier in northeast Georgia. Lake Lanier is approximately 60 mi2 and contains many islands that are used as nesting habitat by a variety of species. Based primarily on tracks and other signs, predators of nesting birds on the islands likely include raccoons, rat snakes, domestic dogs, and opportunistically by a dense population of white-tailed deer. During the pilot study, we created 40 (4 nests on 10 islands) artificial ground nests modeled after Canada geese nests found on the islands from previous nesting seasons by raking leaf litter into a mound with a depression in the center. We placed 3 chicken eggs in each nest, checked for predation after ~ 7 days, and used logistic regression to evaluate the influence of island size, isolation, and the distance of the nest to the island edge on the likelihood of predation. Ten nests were depredated during the study and preliminary modeling results indicate that island size was the most influential variable with predation risk increasing with island size.
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