Linking energy metabolism and echolocation: the relationship between basal metabolic rate and peak frequency in bats

Echolocation is a sensory adaptation that enables bats to navigate and forage in darkness, and its energetic demands may influence their basal metabolic rate (BMR). Peak frequency is the frequency containing the greatest intensity within an echolocation pulse and may contribute to the metabolic cost of sound production in bats. We compiled data on BMR and peak frequency across 11 bat families by integrating original measurements from our laboratory with a comprehensive literature review. Using a phylogenetic comparative approach, we evaluated the relationship between mass-independent BMR and mass-independent peak frequency across all bats, as well as within the families Phyllostomidae and Vespertilionidae. Since Phyllostomidae showed no significant relationship, we reanalysed the dataset excluding this family to assess whether the observed pattern held across species. We found a significant positive relationship between BMR and peak frequency in the full dataset, within Vespertilionidae, and across the order when Phyllostomidae was excluded. These differences may reflect distinct selective pressures, as Phyllostomidae rely on diverse dietary strategies and alternative sensory modalities that reduce their dependence on echolocation for nocturnal foraging. Future research should prioritise paired experimental designs that account for seasonal variation, interindividual differences, and other ecological and physiological factors influencing BMR in bats.