Nest Predators of North American Birds: Continental Patterns and Implications

Identifying nest predators is of fundamental importance to understanding avian breeding ecology and can contribute to identifying broadscale nest-predation patterns. We reviewed 53 North American nest-predator studies, comprising more than 4000 camera-monitored nests, to explore geographic patterns in predator identity and how predation varied with predator richness, habitat, nest height, and bird size. Overall, mesopredators (at high latitudes) and snakes (at low latitudes) were the most frequent nest-predator guilds. Predation by rodents was greatest in the Great Plains and boreal forest and by corvids in the Southwest. Predation by different guilds was often correlated. Predator richness was greatest at midlatitudes but was a poor predictor of predation probability. Nest height and habitat influenced predator-specific predation. The richness of predator species was not influenced by bird body size, nesting height, or habitat type. Our results enable the prediction of regionally influential predators, highlight knowledge gaps, and provide a foundation for further exploration.