Do migratory birds need stopovers for physiological recovery?

• Applicant: Cas Eikenaar, Ph.D.
• Subject Area: Sensory and Behavioural Biology ; Animal Physiology and Biochemistry
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 433146546

Most migrating birds, especially nocturnal migrants, cannot reach their final migratory goal in a single flight and thus have to make stopovers to accumulate new fuel. Stopovers are also commonly thought of as periods during which migrants 'rest' or recover from migratory endurance flight; however, what such rest and recovery encompasses is not well known. As a consequence of nocturnal endurance flight, migrants build up a sleep debt and experience a shift in the balance between damaging pro-oxidants and protective antioxidants towards the former. Therefore it seems plausible that these physiological functions need to be recovered during stopover. I propose to significantly further our understanding of the functions that stopovers have for migrating birds by testing whether (i) migrants can boost their physiological state (oxidative balance and/or sleep) while at stopover, and (ii) the decision to depart from stopover to resume migration is affected by the bird’s physiological state. Hereto, I will collect longitudinal data on oxalic acid concentrations (a bio-marker of sleep debt) and the oxidative balance of migrants at stopover as well as link these to departure decisions.

• DFG Programme: Research Grants