In this new study, we examined telomere length and mitochondrial DNA copy number in migratory and resident Eurasian blackbirds (Turdus merula) on Helgoland. Telomeres are widely regarded as markers of cellular ageing and physiological state, and are thought to shorten more rapidly under oxidative stress, which is a process expected to intensify during energetically demanding events such as migration.

Contrary to expectations, we found that migratory individuals had longer telomeres than resident conspecifics, despite showing similar mitochondrial DNA copy number (a proxy for mitochondrial density). These findings suggest that migratory birds may possess physiological adaptations, such as enhanced antioxidant defences that help them to preserve telomere integrity during migration.

This study was conducted as part of Sophie’s BSc thesis a fantastic piece of work at undergraduate level!