The insectivorous bat Pipistrellus nathusiiuses a mixed-fuel strategy to power autumn migration

• Published in: Proceedings of the Royal Society B: Biological Sciences
• Main Authors: Voigt, Christian C., Sörgel, Karin, Šuba, Jurģis, Keišs, Oskars, Pētersons, Gunārs
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 2012
• Subjects: Pipistrellus nathusii
• Online Access: http://dx.doi.org/10.1098/rspb.2012.0902; https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2012.0902; https://royalsocietypublishing.org/doi/full-xml/10.1098/rspb.2012.0902

In contrast to birds, bats are possibly limited in their capacity to use body fat as an energy source for long migrations. Here, we studied the fuel choice of migratory Pipistrellus nathusii (approximate weight: 8 g) by analysing the stable carbon isotope ratio ( δ 13 C V-PDB ) of breath and potential energy sources. Breath δ 13 C V-PDB was intermediate between δ 13 C V-PDB of insect prey and adipocyte triacylglycerols, suggesting a mixed-fuel use of P. nathusii during autumn migration. To clarify the origin of oxidized fatty acids, we performed feeding experiments with captive P. nathusii . After an insect diet, bat breath was enriched in 13 C relative to the bulk and fat portion of insects, but not deviating from the non-fat portion of insects, suggesting that bats oxidized exogenous proteins and carbohydrates, but not exogenous fatty acids. A feeding experiment with 13 C-labelled substrates confirmed these findings. In conclusion, migratory P. nathusii oxidized dietary proteins directly from insects captured en route in combination with endogenous fatty acids from adipocytes, and replenished their body reserves by routing dietary fatty acids to their body reserves.