Bryan D Watts | Search USGS

USGS2026

Widespread reproductive deficits in Chesapeake Bay ospreys

Introduction: Ospreys ( Pandion haliaetus ) are well-known sentinels of aquatic ecosystem health and are indicators of both environmental contaminants and fish stocks. The Chesapeake Bay supports one of the largest osprey breeding populations in the world, but recent studies have documented declining reproductive performance and increasing food stress in some portions of the estuary. Methods: We monitored osprey nests (N = 571) throughout the Chesapeake Bay during the 2024 breeding season and compared breeding metrics between high-salinity (>10 parts per thousand [ppt]) and low-salinity (<5 ppt) study areas. We also compared contemporary breeding performance within four high-salinity sites to historical data collected during the 1980s. Results: Salinity was strongly associated with breeding performance and the likelihood that pairs achieved productivity levels required for population maintenance. All high-salinity study areas functioned as demographic sinks, whereas low-salinity areas functioned as demographic sources. Breeding metrics including the proportion of pairs breeding, clutch size, nesting failure, brood reduction, and nestling loss all suggested greater food stress within high-salinity areas. Temporal comparisons documented substantial declines in reproductive performance between the 1980s and 2024 within high-salinity study sites. High-salinity sites during the 1980s exhibited breeding performance comparable to low-salinity sites in 2024. Discussion: Although several factors may influence osprey productivity within the Chesapeake Bay, we suggest that reduced availability of Atlantic menhaden ( Brevoortia tyrannus ) is a primary driver of poor reproductive performance within high-salinity waters.

Maryland, Virginia↗

USGS2020

Linking monitoring and data analysis to predictions and decisions for the range-wide eastern black rail status assessment

The US Fish and Wildlife Service has initiated a re-envisioned approach for providing decision makers with the best available science and synthesis of that information, called the Species Status Assessment (SSA), for endangered species decision making. The SSA report is a descriptive document that provides decision makers with an assessment of a species’ current status and predicted future status. These analyses support all manner of decisions under the US Endangered Species Act, such as listing, reclassification, recovery planning, etc. Novel scientific analysis and predictive modeling in SSAs could be an important part of rooting species conservation decisions in current data and cutting edge analytical and modeling techniques. Here we describe a novel analysis of available data to assess current condition of eastern black rail across its range in a dynamic occupancy analysis. We used the results of the analysis to develop a site occupancy projection model where the model parameters (initial occupancy, site persistence, colonization) were linked to environmental covariates, such as land management and land cover change (sea-level rise, development, etc.). We used the projection model to predict future conditions under multiple sea-level rise and habitat management scenarios. Occupancy probability and site colonization were low in all analysis units and site persistence was also low, suggesting low resiliency and redundancy currently. Extinction probability was high for all analysis units in all simulated scenarios except one with significant effort to preserve existing habitat, suggesting low future resiliency and redundancy. With results of these data analyses and predictive modeling, the US Fish and Wildlife Service concluded that protections of the Endangered Species Act were warranted for this subspecies.

Endangered Species Research↗