Prairie wetlands confer consistent migrant refueling conditions across a gradient of agricultural land use intensities

Abstract

Increasing global demands for land to produce food, fiber, and energy threatens temperate grassland and wetland ecosystems, catalyzing a need to inform strategic and efficient approaches to conserve ecological function in these ecosystems. In the Prairie Pothole Region of North America, an extensive agricultural footprint has grown since the late 19th century and recently expanded in extent and intensity of cultivation in response to improved technology and global demands. Despite extensive modifications, many wetlands remain in a matrix of intensively farmed uplands in this landscape. We comprehensively evaluated contributions of those wetlands to spring-migrating ducks by studying two wetland-obligate foragers—lesser scaup (Aythya affinis) and blue-winged teal (Anas discors)—as they migrated to northern breeding ranges. We measured a comprehensive suite of physiological, ecological, and behavioral metrics important during migration in wetlands across a range of upland cultivation intensities at fine and coarse spatial extents. We found no systematic negative responses in invertebrate prey abundance, abundance of migrants, or lipid metabolism of migrant females across the cultivation intensity gradient. Further, abundance and physiology of blue-winged teal and some key invertebrate prey densities were higher in more intensively cultivated landscapes. Our results demonstrated extant wetlands in modern, intensively farmed landscapes make meaningful contributions to spring-migrating ducks despite likely negative impacts of proximate upland cultivation. This insight raises questions about the consequences of agricultural perturbations and the baseline functionality of wetlands in agriculturally productive landscapes that have implications for wetland restoration and conservation strategies employed here and in intensively farmed landscapes globally.