Water Drawdowns and Survival of Marsh Bird Nests at Emiquon Preserve

Marsh birds are a secretive and under-studied group of birds that rely on inundated, dense emergent wetlands for nest construction and protection. To benefit migrating waterfowl, Emiquon Preserve, a cattail marsh along the Illinois River, draws down water from June to August after marsh birds have initiated nesting. Knowledge on the effects of water-level manipulation is limited, and we were particularly interested in learning more about the effects water drawdowns have on nest success, predator access to nests, and juvenile survival. In 2020, we systematically searched suitable habitats and located 135 marsh bird nests (Least Bittern, Common Gallinule, Black-crowned Night-Heron) at varying water depths and distances from the shore. We set up cameras at a subset of nests to record predators at the nests and we revisited the nests throughout the season to document their fate. We will present results on the analyses of predation events and survival as documented on predator cameras and during nest revisits from May to August. We will present analyses of nest survival and juvenile survival from data collected during nest revisits, on camera traps, and from tracking VHF tags.