| Overwater nesting structures can increase mallard ( Anas platyrhynchos) production where low nest survival (<20%) exists in uplands. In 2001 and 2002, I conducted an experiment on 60 wetlands in Prairie-Parkland Canada (near Minnedosa, Manitoba) to test effects of different numbers of structures/wetland (1, 2, or 4) and wetland area (≤0.4 or ≥0.45–1.5 ha) on use of structures by nesting hens, nest success and number of ducklings produced. Use increased between years (average = 28%) and was similar (average = 78%) among numbers of structures/wetland by 2002. Use increased with closeness to roads; on average, used structures were 240 m from roads. Mean numbers of ducklings departing one and 2 structures/wetland were similar (average = 4.61) but twice that of 4 structures/wetland due to egg depredation mostly by corvids. Wetland area was not significant. I concluded that 2 structures/wetland was a cost-effective ({dollar}2.16/fledged duck) strategy to consider among alternative management techniques. |
