Exploring fall migratory patterns of American black ducks using eight decades of band-recovery data

Abstract

As regions of habitat used by migratory waterfowl are subjected to rising anthropogenic pressures, establishing patterns of landscape use during migratory cycles is becoming increasingly important for managing and maintaining populations. Although data collection strategies such as global positioning system (GPS) telemetry promise high-resolution insight on geographic use of contemporary populations, decades of available band recovery records on many species can provide a low-cost, multi-generational alternative for defining broad, historically informed patterns of landscape use. We used nearly a century of band-recovery data to reconstruct patterns of fall migratory landscape use for American black ducks in the Mississippi and Atlantic flyways. We partitioned band recovery positions by month from September to February and spatially analyzed positions using kernel density estimates (KDEs) to delineate geographic regions used by American black ducks and track changes in landscape use during migration. Additionally, we considered the appropriateness of current management strategies, which treat American black ducks as a single population, by testing for differences in month-specific landscape use between ducks banded in the Mississippi and Atlantic flyways, and between international management units (ducks banded in Canada or the U.S.). We found that geographic distributions during peak migration faithfully recovered regions previously hypothesized as migratory corridors. Furthermore, regardless of banding origin, we found highly similar distributions and strong flyway fidelity in Atlantic flyway American black ducks. Conversely, American black ducks banded in the Mississippi flyway displayed differences in landscape use between Canadian and U.S. populations, with Canadian ducks significantly more likely to winter in areas within the Atlantic flyway (i.e., migrate between flyways). Flyway- and population-specific patterns of black duck landscape use indicate populations behave more independently than currently treated by management models (including the Adaptive Harvest Management plan), and that population maintenance may be advanced by managing stocks separately. © 2014 The Wildlife Society.