Automatic multi-capture nest box trap for cavity-nesting ducks

Understanding behavioral and population dynamics of local populations requires information on nonbreeding females as well as alternative breeding strategies such as brood parasitism. To address these issues we developed a new automatic multi-capture nest box trap and captured 165 female hooded mergansers (Lophodytes cucullatus) and wood ducks (Aix sponsa) during 199 trap days in one nesting season at a Missouri study site. The average success for a single trap was 0.8 female/trap/day (<(x)overbar>= 0.2-1.6 females in different time periods and locations). As many as 21 female wood ducks and 12 hooded mergansers were trapped at one site. Multiple captures (2-6 females/check) were often recorded. The most important components of the trap are the swinging false floor, entrance baffle, and counterbalance. The false floor swings downward as soon as a bird settles on it, and returns to the horizontal position after the bird drops into the collection box. Multi-capture nest box traps have several advantages, including automatic operation, ease of setting and operation, minimal need to be checked (only once a day), minimum disturbance to the breeding population, and, most importantly, ability to capture more than one bird daily. These traps can be easily modified (scaled down) to capture smaller cavity-nesting birds.