Sex and State-Dependent Effects on Proactive Behaviors of Bent-Wing Bats Across Contexts

Animals within a population may show distinct behavioral types that differ consistently among individuals over time and across contexts, collectively known as animal personality. Individual state variables arising from intrinsic features of organisms and their interactions with the environment may contribute to or aid in maintaining these interindividual behavioral differences. The present study examined the effects of the body mass, body condition, flight morphology, and parasite load on the personality traits of bent-wing bats Miniopterus fuliginosus. We assessed the bats in three testing contexts, hole-board box (HB), tunnel-box (TB), and flight-tent (FT), that mimicked their natural environmental settings and allowed for different locomotion modes. A PCA analysis loaded the three mutually positively correlated personality traits of the bats, boldness, activity, and exploration, in each context onto a single component of proactiveness. In accordance with the AIC criteria, the sex, body mass, body condition index (BCI), and wingtip shape were selected as predictors for the proactiveness of the bats in the TB and FT tests. In the HB tests, the biomass and abundances of parasitic bat flies were additionally selected but body condition was excluded. We found a negative effect of the body mass on the proactiveness of the female bats in both the HB and FT tests, and that on the proactiveness of the male bats in the HB tests but not so in the FT tests. The sexual differences and negative correlation between the body mass of the bats and their proactive responsiveness are consistent with the mechanism of state-dependent energy assimilation efficiency. Our results may also concur with the predicted feedback mechanism stemming from the characteristic conditions associated with the environment of the bats. This latter inference offers insights for exploring the patterns of personality traits along gradients or seasonality of ecological conditions.