AUTHORS: Victoria Fasbender, Iowa State University; Stephen Dinsmore, Iowa State University
ABSTRACT: Migratory birds rely on stopover sites as a place to rest and refuel before continuing their migration. One site, Lake Red Rock in central Iowa, has implemented a water drawdown by the U.S. Army Corps of Engineers to benefit migrating waterbirds as part of the Sustainable Rivers Program (SRP). Our objectives are to document space use and movement patterns and estimate residency time of fall migrating Pectoral Sandpipers (Calidris melanotos) in relation to the drawdown timing. We fitted Pectoral Sandpipers with GPS satellite tags to gather local and global movement information in 2023 and 2024. Of the 25 birds tagged in 2023, seven stayed at Lake Red Rock during their battery life duration, seven made landfall in either Colombia, Venezuela, or the Dominican Republic, and eleven had their battery die while making a long movement south. Pectoral Sandpipers at Lake Red Rock had an average home range of 10.5 km2 (SD = 11.7) and a mean minimum stopover duration of 8.4 days (SD = 3.4). The average distance traveled at Lake Red Rock per day was 3.4 km (SD = 2.0). The average flight speed of departed birds (n = 18) was 47 km per hour (SD = 5.9). Those that left and made landfall (n = 7) flew an average of 4,788 km (SD = 607) with an average nonstop flight time of 98 hours (SD = 17). Our work showed that sandpipers closely tracked the shallow water/mud interface during their stopover and that their refueling efforts were sufficient to fuel a non-stop flight to northern South America. This work highlights the benefits the SRP can have for migrating waterbirds and encourages similar management at other dammed lakes.
