Reproduction affects flight activity in female and male Daubenton's bats, Myotis daubentoni

Nearly all mammals in the temperate zone breed in spring and summer when climatic conditions are favourable and food is abundant. Similar to other mammals, food requirements of female bats are particularly high during pregnancy and lactation and of males during spermatogenesis. Seasonal changes in energy demand and reproductive condition should therefore result in different foraging activity within and between sexes. This assumption was tested on 16 adult females and 13 adult males of the Palaearctic Daubenton's bat, Myotis daubentoni (Kuhl, 1817), that were radio-tracked during pregnancy, lactation, and post-lactation periods. Pregnant females, as hypothesized, flew significantly longer (mean: 358.9 min; 70% of the night length) than males (mean: 228.5 min; 42.4% of the night length) during spring. In contrast, nightly flight time of lactating females decreased and was significantly less than that of pregnant females, but was similar to that of males during the same period. The longest flight times of males were registered during late summer when spermatogenetic activity is high. However, there were distinct differences in the use of foraging areas between female and male Daubenton's bats. Female bats used small, individual foraging areas during pregnancy and lactation. The pattern was reversed in females after the young had been weaned and in males after they entered spermatogenesis. Overall, the results confirmed Our proposition that flight activity reflects the higher energy demand and nutrition requirements in the different reproductive periods.