Individual study: Low numbers of canvasbacks Aythya valisineria return to release sites following release of captive-bred individuals
Sugden L.G. (1976) Experimental Release of Canvasbacks on Breeding Habitat. The Journal of Wildlife Management, 40, 716-720
Releases of captive bred individuals have the potential to boost wild populations. However they are no always successful or individuals do not always stay in the (presumably relatively safe) release site. This study investigates the release of captive bred canvasbacks Aythya valisineria.
In 1971, 43 female and 47 male canvasbacks were released into an area of parkland with lots of ponds, approximately 50 km east of Saskatoon. The birds were flightless young.
In 1972, birds from the same cohort were released again, this time as yearlings. This time, 50 females and 36 males were released.
The number of birds returning and nesting was monitored.
Three females returned in 1972 with none nesting. Three females returned in 1973, all from the 1972 release, with one nesting.No females were seen more than one year after release.
Most of the yearling females formed brief pairs when released and two attempted to nest.
Of returning females, one of the 1972 releases attempted to nest. None of the 1971 releases attempted nesting.
The survival or return rates of the males was not discussed.
Note: If using or referring to this published study, please read and quote the original paper.