Abstracts

Presented by J. Boomer Malanchuk - Email: bmalanchuk@ksu.edu

Previous research suggests > 90% of wood duck production occurs in naturally forming tree cavities but there has never been a cavity-nesting study in the Atlantic Flyway. Most wood duck nest-site selection and use has been studied in man-made nest boxes, mainly in the Midwest. There remains a need to understand nest-site selection and use in tree cavities. We aim to understand which environmental variables influence nest-site selection by wood ducks in an old-growth silver maple (Acer saccharinum) floodplain forest at Missisquoi National Wildlife Refuge in northern Vermont. We located available nesting tree cavities using two search methods (fixed-area plots [n = 40] and line-transects [n = 130]). We measured tree cavity dimensions with a remotely operated camera and in-tree via double-rope climbing technique. We used Akaike Information Criterion model selection to understand the effects of cavity height from ground, area of cavity opening, and DBH of tree on tree cavity selection. We monitored 47 tree cavities that met predetermined size and conditions for use (fixed-area plots = 8, line-transects = 30, and opportunistic encounters = 9). Wood ducks selected tree cavities higher from the ground and with smaller relative cavity opening dimensions. We did not detect any tree cavity use by waterfowl in 2015 from the 8 cavities monitored. In 2016, 12 of 47 identified cavities were occupied though none produced a successful clutch. Nest failures were attributed to predation (58%, n = 8) and abandonment (42%, n = 5). Predation, or perceived predation, was considered the main driver of nest-site selection. We simultaneously monitored nest boxes (n = 20) and observed high nest success (2015 = 61%, 2016 = 27%) and high nest parasitism (2015 = 75%, 2016 = 27%).