Do Effigies Deter Fish Crows Hunting in a Black Skimmer Colony Mid-season?

Rynchops niger (Black Skimmer) is a colonial-nesting seabird that nests on open, sandy or gravel beaches. In densely populated Pinellas County, FL, Black Skimmer colonies often occur on municipal beaches where there is relatively little mammalian predation, but intense predation by Corvus ossifragus (Fish Crow) and Leucophaeus atricilla (Laughing Gull). In 2013, a previously successful Black Skimmer colony experienced high egg-loss due to Fish Crow predation. To determine if effigies would decrease egg depredation in the middle of the breeding season, we monitored the number of crow-foraging passes over the colony and number of eggs taken before and after we placed 6 crow effigies among the nests. During 36 hours of monitoring, we observed 83 foraging passes and 28 eggs being taken by Fish Crows. Neither foraging passes nor eggs taken decreased after the placement of the effigies, and the Black Skimmers abandoned their nests. Future research should focus on other methods to limit nest predation after the onset of the breeding season.