Plasma phospholipid profile of two subspecies of a long-distance migratory songbird, the Northern Wheatear Oenanthe oenanthe

This is the authors' abstract. We don't add key points for this paper.

Birds have specific metabolic adaptations that affect their migratory performance and enable them to cope with the challenges of long-distance migration. A novel field in assessing these adaptations is lipidomics, which allows analysing the composition, function, and dynamics of lipids within cells, tissues and organisms. To date, lipidomic studies in birds have mostly focused on poultry and little is known about how specific lipid species reflect fuel loads in wild birds during migration and how different migratory strategies, i.e. traveling in short steps or crossing ecological barriers in long non-stop flights, can lead to or are governed by differences in the lipid profile. Phospholipids could play a crucial role in this, as they are among the most important structural lipid components of biological membranes. They significantly influence membrane function and may represent an important pathway for dietary fatty acid transport. This process potentially facilitates fat deposition during endurance flight – an aspect whose significance has largely been overlooked until now. On the small island of Helgoland in the German Bight, two subspecies of the Northern Wheatear Oenanthe oenanthe stop over during spring migration before flying to their separate breeding grounds, following two different migratory strategies. We investigated the phospholipid plasma profile of O. o. oenanthe and O. o. leucorhoa to answer the question to what extent phospholipid profiles differ (1) depending on the bird's condition and (2) between different migratory strategies. We found evidence of a cross-over interaction between subspecies, relative fat mass and phospholipid concentrations, suggesting that both bird condition and migratory strategies may play an important interactive role in the observed phospholipid profiles. Furthermore, the highlighted phospholipids are potential candidates for future studies on biochemical and physiological mechanisms of endurance flight, contributing to a deeper understanding of the ‘optimal' lipid composition linked to migration. Additionally, the exploration of lipid species associated with specific migratory states presents an opportunity to integrate such phospholipid data into mathematical models designed to predict migratory success and strategies.