There is increasing recognition of the importance of wetlands in the prairie pothole region (PPR) of the northern United States for stopover habitat for spring-migrating waterfowl. The quality and quantity of stopover habitat found near breeding areas can affect speed and success of migration and subsequent breeding events. Conservation and management of wetlands in the region has traditionally focused narrowly on reproductive phases of the life cycle, and little to no research has examined how ducks use a diversity of available wetlands in the region during migration. We conducted weekly surveys on 1,061 wetlands during spring 2018 and 2019 to examine factors affecting duck use of wetlands in the intensively modified southern PPR landscape of Iowa, USA, for wetland restoration and conservation strategies. We compared wetland types, which included farmed, seasonal, and semi-permanent wetlands, and lakes. The highest duck use per unit area occurred on semi-permanent wetlands, followed by seasonal, and then farmed wetlands, and lakes. Ducks were highly clustered in our study, with 75% of all use-days occurring on only 37 wetlands comprising 41% of all wetland area surveyed. We used hurdle models to examine how local and landscape factors measured within and around wetlands influenced duck use during spring migration. Multiple factors related to duck use at local and landscape scales, such as wetland area, vegetation abundance, and number of wetlands in the surrounding landscape. Among semi-permanent wetlands, local factors within wetlands were more important than landscape factors in determining duck use. Collectively, our findings suggest semi-permanent wetlands within the PPR play a key role in transitioning birds from wintering areas to breeding areas and that management of semi-permanent wetlands should promote interspersion of emergent vegetation and open water and growth of submersed aquatic plants to improve their function for migrants.

There is increasing recognition of the importance of wetlands in the prairie pothole region of the northern United States for stopover habitat for spring-migrating waterfowl because the quality and quantity of stopover habitat can affect speed and success of migration. However, conservation and management of wetlands in the region has traditionally focused narrowly on reproductive phases of the life cycle, and little to no research has examined how ducks use the diversity of available wetlands during migration. We conducted weekly surveys on 1,061 wetlands during the springs of 2018 and 2019 to examine factors affecting use of wetlands in the intensively modified southern PPR landscape of Iowa to inform restoration and conservation strategies. We compared wetland types while accounting for area, which included farmed, seasonal, and semi-permanent wetlands, and lakes and found highest duck use on semipermanent wetlands followed by seasonal and then farmed wetlands. We examined how local and landscape factors within and around wetlands influenced duck use during spring migration.We found multiple factors related to duck use at both local and landscape scales, such as the vegetation structure and density, depth, and number and area of wetlands on the surrounding landscape. Among the most used wetlands, semi-permanent wetlands, we found local factors 7 within wetlands were more important than landscape factors in determining duck use.Collectively, our findings suggest semi-permanent wetlands within the PPR play a key role in transitioning birds across this landscape during migration and that management there to promote interspersion of emergent vegetation and open water and submerse aquatic plants could improve their function for migrants.

Gizzard helminths were examined in 100 (50 adult, 50 juvenile) female northern pintails ( Anas acuta). Sixty-three individual helminths, representing 5 species ( Amidostomum acutum, Echinuria uncinata, Epomidiostomum uncinatum, Streptocara crassicauda, and Gastrotaenia cygni) were found. Twenty-seven northern pintails were infected with 1-3 helminth species and averaged 1.4 species. Overall, A. acutum and G. cygni were the most prevalent and abundant species (20%, n = 31 and 10%, n = 25, respectively), followed by S. crassicauda (5%, n = 5), E. uncinata (1%, n = 1), and E. uncinatum (1%, n = 1). Intensity of infection for A. acutum, E. uncinata, E. uncinatum, S. crassicauda, and G. cygni was 1.6 ± 0.3 [SE], 1.0 ± 0, 1.0 ± 0, 1.0 ± 0, and 2.5 ± 0.6, respectively. Our findings represent new information about gizzard helminth infections in northern pintails wintering along the Texas coast.