Stopover ecology of the least sandpiper (Calidris minutilla) in Iowa: implications for reservoir management

Abstract

Vanausdall RA, Dinsmore SJ. 2021. Stopover ecology of the least sandpiper (Calidris minutilla) in Iowa: implications for reservoir management. Lake Reserv Manage. 37:300–312. Multipurpose reservoirs can be used to manage habitat for shorebirds during migration, an energetically costly event that may influence demographics and population numbers. This is particularly true for shorebirds that migrate through the interior of the United States, which has lost much of its wetland habitat. Shorebirds use aquatic systems during stopover periods throughout migration to rest and refuel. Understanding the factors that influence the probability of a shorebird remaining at a stopover area can inform decisions regarding reservoir management. We examined the influence of habitat and environmental covariates and body condition on the daily local residency probability of migrant least sandpipers (Calidris minutilla) at Saylorville Lake, a reservoir in central Iowa. We monitored 189 least sandpipers in fall 2016, 2017, 2019, and 2020 using radiotelemetry. Using a nest survival model, our most competitive model included significant negative effects of water level (β = −8.35, 85% CI = −11.18, −5.52) and body condition (β = −4.91, 85% CI = −6.82, −3.01) on residency probability. We calculated a mean daily local residency probability of 0.78 (95% CI 0.56, 1.00) and used this value to calculate a minimum stopover duration of 3.96 d (95% CI = 3.45, 4.46). Our findings indicate that the timing of water level management at Saylorville Lake can impact the residency probability of the least sandpiper. Drawing down water levels just prior to fall migration and maintaining water levels at or below the conservation pool level (254.8 m) can provide habitat for this species and likely other shorebirds.