cinematic food-recorder" which automatically triggered photographs of prey in the bills of Great Tits (Parus major) each time they perched on a trigger mechanism at the entrance of their nest-box. In the subsequent 50 years, ornithologists have employed

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.

No abstract

Predation is the leading cause of nest failure for most birds. Thus, for ornithologists interested in the causes and consequences of variation in nest success, knowing the identity and understanding the behavior of dominant nest predators is likely to be important. Video documentation of nests has shown that snakes are frequent predators. Here we reviewed 53 North American studies that used nest cameras and used these data to identify broad patterns in snake predation. Snakes accounted for 26% (range: 0–90%) of recorded predation events, with values exceeding 35% in a third of studies. Snakes were more frequent nest predators at lower latitudes and less frequent in forested habitat relative to other nest predators. Although 12 species of snakes have been identified as nest predators, ratsnakes Elaphe obsoleta, corn snakes E. guttata and fox snakes E. vulpina were the most frequent, accounting for > 70% of all recorded nest predation events by snakes and have been documented preying on nests in 30–65% of studies conducted within their geographic ranges. Endotherm‐specialist snakes (Elaphe and Pituophis genera) were more likely to depredate nests in forests and the canopy relative to other snakes, due to their affinity for edge habitat. Predation by only ratsnakes and corn snakes was predominantly nocturnal and only ratsnakes were more likely to prey on nests during the nestling stage. Snakes were not identified to species in over 30% of predation events, underlining the need for more complete reporting of results. A review of research to date suggests the best approach to investigating factors that bring snakes and nests into contact involves combining nesting studies with radio tracking of locally important snake nest predators.