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Canvasback production on the experimental block improved significantly and remained high until declining during the severe drought of 1988. On average, 221 canvasback ducklings were hatched on the experimental area each summer versus 112 on the control area. Apparent nesting success for fenced and unfenced nests, for all years combined, were 77% and 50%, respectively. In 1984-85, this difference was 88% versus 23%; in later years there was little difference between fenced and unfenced nests. We speculate that fences reduced the likelihood of predators locating nests by deflecting searching animals away from nest sites. Nest survival was greater when several meters of thick cover was present between the fence and the nest. We suspect that fences did little to deter predation if predators detected a nest or a hen. By 1988, the experimental population had grown to greater than 9.6 pairs per km², up 163% from 1983, and more than doubled the highest density of breeding canvasbacks recorded at Minnedosa in 33 years. Populations in the control area fluctuated, as expected, following variation in nesting success. Clearly, recruitment of young, as influenced by nest success and redhead parasitism, is a major factor affecting numbers of canvasbacks at Minnedosa. If duckling production can be improved it appears that young female canvasbacks will home and local population densities can be increased.