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A Walk-in Trap For Nesting Ducks

Results and Discussion

We deployed the described trap on 41 mallard nests during late incubation and captured 36 (88%) females during summers of 1987 and 1990-1991 (32 in S.D. and 4 in Minn.). At 24 nests where we recorded the number of trapping attempts, 18 (75%) females were captured on the first day of trapping, 5 (21%) on the second day, and 1 (4%) on the third day. Failed capture attempts were caused by females escaping through the funnel before it could be blocked. Amid short vegetation, mallards may have observed us, and they sometimes left their nests before our final approach. No females or nests were harmed during trapping. Of 41 attempted captures, only 1 (2%) abandoned while the trap was set over the nest. After capture, 29 (81%) females hatched their clutches, 6 (17%) abandoned, and 1 (3%) female was killed by an avian predator.

In 4 (10%) of the 41 capture attempts, traps were set with the intention of returning the next morning, but high winds and waves precluded travel to the nesting island. Upon return, the clutches had hatched and females had led their broods through the opening of the trap. Incubating females apparently had no difficulty leaving or reentering the trap during nest recesses. Escape of mallards before capture and subsequent return to the nest and trap supports our contention that females could easily move in and out of traps.

We modified our trap to fit around nests in various terrain and vegetation. We built a trap to fit within a pile of rocks by joining several pieces of wire fencing together and cutting the bottom to fit curves of individual rocks. Instead of stakes, rocks wedged against the side were used to hold the trap in place. In 2 instances, a trap was cut in half and placed around the trunks of eastern juniper (Juniperus virginiana) to capture the females nesting under the lowermost branches. A trap also was modified to capture a female nesting under a fallen tree.

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