Abstracts

Presented by Todd Arnold - Email: arnol065@umn.edu

Knowledge of band reporting is important for converting band encounter data into estimates of harvest probabilities, which can then be used to assess harvest management goals or estimate population size and other vital rates. Historical estimates of band reporting probabilities have come from reward band studies or joint analysis of band recovery and harvest survey data, but there are long gaps between estimates, and most studies have focused exclusively on mallards (Anas platyrhynchos). We compiled 337 published estimates of band reporting for North American waterfowl and conducted a Bayesian state-space analysis to provide a continuous time series of estimated band reporting probability from 1948 to 2010. Band reporting probability increased sharply between 1996 and 2000 when toll-free phone numbers were added to band inscriptions and agencies implemented electronic methods for band reporting, but our analysis also identified gradual long-term trends in reporting probability throughout the time series. We found little evidence for among-species variation in reporting probability, but species that are widely regarded as trophies by waterfowl hunters (e.g., certain diving ducks, Aythya spp., and northern pintails, Anas acuta) had higher reporting probabilities than mallards. We also found little evidence of geographic variation in reporting probabilities, although we confirmed lower reporting probabilities for eastern Canada. We recommend using our estimates of band reporting probabilities and their variances as informed priors in future analyses of band recovery data to fully embrace uncertainty about how this parameter affects estimates of other population parameters. Retrospective studies using parts collection data are needed to explore potential among-species differences in reporting probabilities during recent decades.