| dc.description.abstract | Bio-logging is a popular method to collect scientific data in the field of animal ecology. The presumption is that bio-logging should allow the study of animals with only minor disturbance to their natural behaviour and thereby avoid biased data. However, tagging may be stressful and may cause deleterious effects and alter natural responses or behaviour of animals. Knowledge of negative impacts associated with the tagging of animals should be assessed when possible. Bio-logging studies often lack a control group, and the adverse effects of tagging may therefore not be observable. In this study, I investigated whether glue-on tagging affected Eurasian beavers (Castor fiber) body mass and growth per day. I predicted that tagged individuals would experience reduced body mass, and externally attached tags would negatively affect beavers' growth rate per day in comparison with un-tagged beavers (control group). Thirty-one adult free-ranging beavers were tagged, and 47 un-tagged beavers were used as a control group. Linear mixed models (LMM) were used to model body mass and growth per day. Analysing differences in body mass within the tagged individuals only, showed an inconclusive result where all explanatory variables were uninformative, which indicate no substantial effect from the tag. However, analysing the tagged and un-tagged beavers combined indicated that the glue-on tag negatively affected the beavers' growth per day. This result emphasised the importance of using a control-group to reveal adverse effects that might have implications for animal welfare and sampling of biased data. Whether the adverse effects were caused by extended handling time, drag or thermoregulation are unknown. The glue-on tag likely interferes with the beaver's fur and insulation, which might be a significant factor for the decrease in beavers' growth. However, this study only investigated the short-term effect of tagged individuals. Future studies are needed to test if these effects are prolonged over time. | en_US |
