Ecology and predation behavior of corn snakes (Pantherophis guttatus) on avian nests

Relatively little is known about the ecology of free-ranging Corn Snakes (Pantherophis guttatus), although they have been implicated as regionally important avian nest predators. We used nest camera data from 97 snake predation events, 25% of which were attributable to Corn Snakes, to assess how the ecology and behavior of nest predation by Corn Snakes compares to that of sympatric snakes that predate nests. Unlike Ratsnakes (P. alleghaniensis) and Racers (Coluber constrictor), Corn Snakes more frequently preyed on nests located away from forest edges. Nest predation by Corn Snakes, like that by Ratsnakes and Racers, increased over the nesting season. Of the four snake species documented preying on nests at our site, Corn Snakes were the only exclusively nocturnal nest predator, arriving at nests between 2024 and 0220. Corn Snakes were nearly five times more likely to prey on nestlings than eggs, suggesting that they may locate nests visually during the day. On four occasions Corn Snakes arrived at nests shortly after or while other snakes preyed on nestlings, indicating that Corn Snakes may use cues provided by other snakes to locate prey. Unlike other snake species, Corn Snakes never struck at adult birds on the nest and often actually pushed sleeping adults off the nest or pushed under them to access nestlings. Although Corn Snakes do not appear to present nesting birds with unique challenges for avoiding predation, Corn Snakes do present researchers with intriguing questions about their foraging behavior.