Many avian species display pre-fledging mass recession, whereby nestlings routinely lose a significant fraction of their body mass in the days prior to their first flight. Despite its prevalence, our understanding of the adaptive function and mechanism for this process is far from complete. Previous studies have employed weight treatment experiments to test if nestlings can control pre-fledging mass recession, producing mixed results and suggesting interspecific variation in the mechanism. Furthermore, no study has investigated how this process affects the development of other somatic and physiological traits, and whether this varies by the environmental context. To address this, we tracked the somatic and physiological development of European starlings (Sturnus vulgaris) in response to an experimental increase in their mass preceding fledging. We separated four nestlings (n = 97) in each brood (n = 26) into treatment (n = 46) and control (n = 51) groups. Two nestlings were fitted with 4g (5% BM) weighted backpacks at 15 days old, six days before fledging age, with two nestlings receiving no treatment. Weighted nestlings lost significantly more mass than controls, partially compensating for the weight addition by losing 2.4g on average more between ages 15 to 20. Furthermore, weighted nestlings lost significantly more mass than controls only in the days immediately following treatment (i.e. ages 15 – 17), with no significant difference in mass lost between groups in the latter stages of the experiment (i.e. ages 17 – 20). This accelerated mass recession following treatment was associated with increased tarsus growth and reduced wing growth. Together, our data suggest that European starlings can facultatively adjust pre-fledging mass recession and that experimentally accelerating this process results in varied developmental trajectories.