Compounded risks to beach-nesting seabirds in developed areas: environmental and anthropogenic disturbances at Black Skimmer colonies

Wildlife in coastal zones is often affected by anthropogenic and environmental factors that intensify at the interface of land and water. Seabirds are particularly susceptible to disturbances when they breed in large, dense colonies, such as direct harm from extreme weather and interference, or exposure of eggs and chicks to predators due to indirect human activities. All these factors potentially impact the Black Skimmer (Rynchops niger), a seabird that is considered vulnerable in much of its range across the Americas. This study quantified disturbances affecting two skimmer colonies within a Critical Wildlife Area in southwest Florida, a coastal area of rapidly growing human population. Skimmers experienced a wide array of disturbances that caused a total of 195 flushing events, at a rate of almost 2 per hour throughout the 3-month study period. Natural and anthropogenic disturbances were occurring simultaneously and at roughly similar frequencies at the two colonies. Weather and unexplained disturbances caused a higher portion of skimmers to flush at one colony, and weather led to longer flushing events at the other colony. Flushing responses were stronger on weekends at the second colony. Notably, breeding skimmers faced considerable disturbance despite existing within a monitored protected area. Given the overlap of disturbance types across the breeding season, this study demonstrates the need for measures to protect skimmers from anthropogenic and environmental stressors, including further study of how these factors impact reproductive success of colonies. It illustrates the challenges faced by waterbirds around the globe, amid growth in coastal human communities during this era of rapid environmental change.