Experimental Release of Canvasbacks on Breeding Habitat

Abstract

Of 43 female canvasbacks (Aythya valisineria) released as flightless young on a 15.5-km2 study area near Saskatoon, Saskatchewan, in 1971, 3 returned to the general area of release in 1972. There was no evidence that they nested. A majority of 50 hand-reared females, spring-released as yearlings in 1972, formed brief pair bonds with wild males. None apparently produced broods though two attempted to nest. Three returned as 2-year-olds and at least 1 nested. No released birds were seen in second or subsequent years after release. There was no advantage in overwintering the ducklings before they were released as yearlings. Because the area may have been fully stocked with wild canvasbacks, similar releases should be evaluated on obviously understocked habitat. J. WILDL. MANAGE. 40(4):776-720 Persistently low populations of canvasbacks dictate a need to investigate all facets of the species' ecology and to test management practices for improving its status. Artificial stocking as a way to increase canvasback breeding populations has received little attention and only one attempt has been reported. In that study, an insufficient number of ducklings was released to evaluate the technique (Foley 1954). This paper describes an experiment to increase breeding densities of canvasbacks artificially by transplanting flightless young and by spring release of yearlings. I thank J. B. Gollop, J. H. Patterson, and Journal of Wildlife Management referees for their helpful comments.