Evaluation of a 2-season banding program to estimate seasonal and annual survival probabilities of migratory birds: a case study of American black ducks and eastern mallards.

The management of North American waterfowl is predicated on long-term, continental scale banding implemented prior to the hunting season (i.e., July–September) and subsequent reporting of bands recovered by hunters. However, single-season banding and encounter operations have a number of characteristics that limit their application to estimating demographic rates and evaluating hypothesized limiting factors throughout the annual cycle. We designed and implemented a 2-season banding program for American black ducks, mallards, and hybrids in eastern North America to evaluate potential application to annual life cycle conservation and sport harvest management. We assessed model fit and compared estimates of annual survival among model types (i.e., 2-season and single season by banding season) to evaluate model assumptions and potential application to population modeling and management. Estimates of annual survival and patterns among age and sex cohorts using pre-season and 2-season models were similar to previously published results. We found patterns of seasonal survival varied by species, age, and to a lesser extent, sex. Our results suggest the 2-season model generally fits well with the most consistent lack of fit being due to black ducks in the post-season banded cohort. There was generally high agreement between annual survival estimates from the 2-season model and pre- and post-season data only model. Hunter recovered birds exhibited similar spatial distributions regardless of banding season suggested both banded samples were from the same population, though the Goodness-of-Fit test suggests this assumption was violated in some regions and years. We conclude the estimates of seasonal and annual survival for black ducks and mallards based on the 2-season banding program are valid and accurate based on model fit statistics, similarity in survival estimates across models, and similarities in the distribution of recoveries. The 2-season program provides greater precision and insight into the survival process and will improve the ability of researchers and managers to test competing hypotheses regarding population regulation resulting in more effective management.