Abstracts

Presented by Frank C. Rohwer - Email: frohwer@deltawaterfowl.org

"Hunters in some areas experienced poor waterfowl hunting and reported observing fewer ducks in recent years. Conspiracy theories re-emerged – NGOs (including Delta) and agencies were accused of nefarious dealings to change duck distribution. While complaints are not new, we think it reasonable to examine duck demography changes that may be altering duck distribution, availability for harvest, and vulnerability to harvest throughout the flyway. We address or speculate on the following hypotheses: 1) Breeding grounds productivity is a more important driver of hunter success in southern latitudes. We hypothesize that northern latitude hunters benefit from “opening day” effects that render all ducks naïve to harvest, but by late fall and winter, adult birds have become wary and only juveniles remain relatively naïve. We predict that correlations between harvest rates and BPOP will be stronger in the north, whereas correlations between harvest rates and fall flights will be stronger in the south. 2) Age and sex ratio changes (more male biased) over time have exacerbated hunter frustrations in the south more than the north. 3) The rich (in ducks) have gotten richer and the poor have gotten poorer in mid-latitude and southern states due to intensive habitat management and perhaps harvest management on hunting clubs. 4) Ducks in the winter show higher philopatry than expected based on apparent duck distributional shifts. This may exacerbate hypothesis 3. 5) Spinning wing decoys have contributed to the demise of more ducks, perhaps the most productive females, which has disproportionately impacted hunters in southern latitudes. We acknowledge that waterfowl managers have a limited control over where and when ducks migrate and are available to hunters. However, understanding how duck production, fall flights, and sex ratios impact hunter harvest is requisite to understanding how management practices can impact hunters in different segments of the flyway.