No evidence of hyperphagia during pre-hibernation in a northern population of little brown bats (Myotis lucifugus)

During autumn, temperate bats must deposit fat stores for hibernation. Populations at high latitudes face four challenges: a shorter active season and shorter nights during the active season (less time to accumulate fat), a longer hibernation period (larger fat store needed), and colder nights (reduced prey availability). Mating also occurs during the pre-hibernation period, placing time constraints for mating and fattening on northern populations. We tested the hypothesis that these factors constrain pre-hibernation foraging in northern populations of little brown bats (Myotis lucifugus LeConte, 1831). We measured plasma triglyceride concentration to study pre-hibernation fueling rates of a population near the northern range limit of the species, and compared our results with previously published results from a more southern population. In contrast to bats at lower latitude, we found consistently low concentrations of plasma triglycerides, indicating a low fuelling rate throughout the pre-hibernation period. However, despite an apparently low fuelling rate, bats achieved a substantially greater body mass. The discrepancy between populations suggests that environmental constraints lead northern populations to employ different behavioural or physiological strategies to prepare for hibernation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author