Factors affecting survival of mallard ducklings in southern Ontario / Steven T. Hoekman, T. Shane Gabor, Ron Maher, Henry R. Murkin, and Llwellyn M. Armstrong.

Includes bibliographical references (pages 493-495).

Survival of young is poorly understood, but important to fitness and demographics
for many birds. Estimates of duckling survival and the factors influencing it are
essential to guiding regional breeding management for ducks. We estimated daily and 30-
day duckling survival for Mallards (Anas platyrhynchos) at one of four sites each year during
1997–2000 in southern Ontario, Canada. We examined effects of site-year, brood age, female
age, and hatching date on survival. Our best model supported additive effects of site-year,
brood age, and hatching date. The odds of daily survival were 8.8 times (95% CI: 4.2–18.5)
higher for older (.7 days) relative to younger (#7 days) ducklings and 1.7 times (0.9–3.1)
higher for early-hatched (before 1 June) relative to late-hatched (1 June or later) ducklings.
When controlling for differences in hatching date, we did not find support for an influence
of female age. Mean 30-day duckling survival across sites was 0.40 (range 0.07–0.50).
Extremely low survival at one site appeared to be associated with poor wetland conditions.
Our results suggested directional selection for early nesting, and we predicted that early
nests made a disproportionately large contribution (61%) to recruitment to 30 days posthatching.
We recommend management emphasis on protection, enhancement, and restoration
of seasonal wetlands to prevent declines in duckling survival.