Effects of blood sampling in Great Tits

Because of legal requirements in different countries as well as moral and e thical considerations, the effects of behavioral studies on animal welfare should be quantified. In this study, the effects of brood sampling on juven ile and adult Great Tits (Poecile major) were examined. Direct injuries wer e looked for as a possible short-term effect. We also quantified survival u ntil fledging of nestlings that were bled versus those that were not bled a s a possible medium-term effect, and survival until the next breeding seaso n as well as the reproductive success in the year following the treatment w ere investigated as possible long-term effects. We found no effects of bloo d sampling in each of these instances.