Effects of neckbands on body condition of migratory geese

Abstract

Ringing and marking are widely used techniques in avian ecology to assist studies of migration, survival and behaviour, and often used to estimate population sizes. Only rarely, however, have the effects of these markings on bird viability been thoroughly tested. Using an abdominal profile index of marked geese and body mass of recaptured birds previously marked, this study investigated the effect of neckbands on body condition of Pink-footed Geese Anser brachyrhynchus at different temporal scales, and evaluated to what extent capture, handling and banding affected these birds on short, medium and longer terms. Our results indicated that body condition of geese were negatively affected in the days immediately succeeding capture, but that only a minor effect persisted on a seasonal scale. We found no support for a long-term effect of neckbands on the body mass of individual birds, indicating that the capture and handling event might be the main contributory cause to the transitory decline in body condition. Pink-footed Geese thus seemed to habituate almost completely to the presence of neckbands, and the effects on long-term body condition can be expected to be minor. However, neckbands might still influence important life-history traits such as reproduction and survival by means of, e.g., altering social interactions, increasing predation or interfering with mate acquisition.