Blood Metabolites and Profiling Stored Adipose Tissue Reveal the Differential Migratory Strategies of Eurasian Reed and Sedge Warblers.

Autor: Araújo, Pedro M., Viegas, Ivan, Da Silva, Luis P., Lopes, Pedro B., Tavares, Ludgero C., Ramos, Jaime A.
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Zdroj: Birds (2673-6004); Dec2022, Vol. 3 Issue 4, p359-373, 15p
Abstrakt: Simple Summary: Through the examination of several blood metabolites in two migratory warblers at two stopover sites in Portugal, Sedge warblers showed higher values of triglycerides (TRIG) + glycerol (GLY) than Eurasian Reed warblers, both during post-flight fasting and when stopping naturally. The higher values of TRIG + GLY in circulation should reflect a higher fat reserve mobilization by Sedge warblers, attributed to the fewer possibilities to refuel, relying more on fat reserves during their migratory journeys than those of Eurasian Reed warblers. Sedge warblers use more lipids or more efficiently the reserves in each migratory step, due to longer fasting periods causing lower glycaemia levels. Our study revealed differences in the level of unsaturation subcutaneous fatty acids, mainly the higher levels of polyunsaturated fatty acids in Sedge warbler. Differences in preying habits may trigger a series of adaptations that results in different migratory strategies between Sedge and Eurasian Reed warblers. The overall speed of bird migration is limited by the amount of fuel stores acquired during the initial phases of migration. The ability to mobilize fat is crucial for migratory birds that can exhibit different migratory strategies. Birds mobilize triglycerides during nocturnal flight thus increasing circulating fatty acids and glycerol to meet the metabolic demands of flight. Eurasian Reed (Acrocephalus scirpaceus) and Sedge (Acrocephalus schoenobaenus) Warblers were captured at Portuguese stopover sites during spring and autumn migration. These species were selected based on their different migration strategies and dietary preferences during migration. Blood metabolites and fat composition were analyzed to determine their nutritional states. Sedge Warblers had higher blood triglyceride and glycerol levels during post-flight fasting than in non-fasting periods. Furthermore, Sedge Warblers had higher triglyceride and glycerol levels than Eurasian Reed Warblers in both post-flight fasting and non-fasting condition. The differences found may reflect distinct approaches in re-feeding activity (e.g., feeding intensely) associated with the number of stopovers during migratory cycle. Dietary preferences affect the fat composition available for oxidation during long-term exercise in migratory flight. Nuclear magnetic resonance analysis of subcutaneous fat composition revealed that Sedge Warblers presented higher levels of polyunsaturated fatty acid levels than Eurasian Reed Warblers. The distinct lipidic profiles observed and differences in feeding ecology may explain the different migration strategies of these species. Overall and despite their ecological similarity, our study species showed pronounced differences in blood metabolites levels and subcutaneous fatty acids composition, likely attributed to the migratory strategy and foraging preferences during their migratory cycle. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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