Probability of survival and breeding for juvenile female canvasbacks

Few studies have examined factors affecting the probability of recruitment into breeding populations by juvenile ducks. We were able to do this for ju venile female canvasbacks (Aythya valisineria) at Minnedosa, Manitoba, Cana da, 1983-1988 by combining estimates of duckling survival, annual survival, and breeding probability. Annual survival probability increased with duckl ing weight, declined with advancing hatch date, and was lower in)ears with more liberal than conservative han rst regulations. Breeding probability wa s lower during years with relatively dry wetland conditions than years with wetter conditions, and it also declined with advancing hatch date. Estimat es of breeding probability ranged from 0.54 to 0.94 for juveniles and 0.74 to 0.95 for adults. Recruitment probability for juveniles ranged from 0.12 to 0.28 at the mean of tile covariates (body mass and hatch date) and from <0.01 to 0.43 at the extremes. More than 54% of the recruits were ducklings produced in nests that hatched early. The per-capita contribution of recru its by hens that hatch nests early may be even more disproportionate becaus e clutch size and nest success generally: decline with advanced laying date . Managers should recognize that late, dry breeding seasons will likely res ult in pool recruitment of hatched ducklings. Where possible, habitat manag ement should facilitate early nesting by canvasbacks.