Foraging behavior of a desert dwelling arthropod-gleaning bat (Otonycteris hemprichii) during pregnancy and nursing

We studied the role of behavioral activities used by desert-dwelling, arthropod gleaning Hemprich’s long-eared bat (Otonycteris hemprichii), hypothesizing that there is a trade off between their own and their offspring's food needs. Specifically, we tested the following predictions: 1) females will bring forward their emergence time from their roosts and increase foraging bout length progressively from the first through the second trimesters of pregnancy, and during nursing as their pups grow; but, that 2) during the last trimester of pregnancy, namely, in the final stages of foetus development, females will emerge later and there will be a reduction in foraging effort (time); and that 3) females will spend more time foraging during nursing than during pregnancy. We found that the bats emerged from their roosts to forage earlier during the first trimester, but not during the last two trimesters of pregnancy, and that they did not change their emergence time as nursing progressed. Bats that emerged later at night during pregnancy spent more time foraging, and, except for the third trimester, the length of the first daily foraging bout increased as both pregnancy and nursing progressed. Total daily foraging time increased as pregnancy and nursing progressed. Generally, these results support our hypothesis; through adjustment of their foraging behavior as embryos and pups develop, breeding female Hemprich's long-eared bats contend with the potentially conflicting food requirements of their offspring and their own needs.