Survival and movements of canvasback ducklings / Jerome P. Leonard, Michael G. Anderson, Harold H. Prince, and Robert B. Emery.

Includes bibliographical references (pages 872-874).

Because canvasback (Aythya valisineria) breeding areas have been reduced by wetland drainage and because density-dependent factors that limit survival of ducklings are poorly understood, we studied brood and duckling survival during 1983-90 and overland brood movements during 1988-89 on 2 study blocks (15.8 km2 each) near Minnedosa, Manitoba. One block was designated as the experimental area canvasback duckling production was experimentally enhanced, whereas the other block was an unmanipulated control. Individually marked female canvasbacks with ducklings were monitored to test the effects of vasback brood density, presence of parasitic redhead (A. americana) ducklings, hatching date, and water levels on canvasback duckling survival. We observed no between-block differences in mean daily survival rates of canvasback ducklings during 1983-86. The experimental high-density area had higher < 0.05) duckling survival probabilities during 1987-88. Duckling survival was significantly related (0.033) to duckling density but not (P = 0.56) June wetland water levels. Duckling survival probabilities were highly variable among years (range = 0.027 ? 0.007 [SE] to 0.623 + 0.004 [SE]); survival rates in 1989-during severe drought were much lower than in previous years. We observed no consistent effect of hatching date on duckling survival among years. On the experimental study block in 1988, canvasback ducklings broods containing parasitic redhead ducklings had lower (P = 0.013) survival during the first 7 days of Canvasback broods were observed on an average of 4 different ponds and traveled an average total overland distance of 1.5 km with no between-block differences. Density-dependent mortality of ducklings was not factor in limiting recruitment of canvasbacks in the Minnedosa area.