Atmospheric humidity affects global variation of bat echolocation via indirect effects

The peak frequency of bat echolocation is a species-specific functional trait linked to foraging ecology. It is tailored via evolution to suit conditions within the distribution range of each species, but the evolutionary drivers are not yet well-understood. Global patterns of humidity correlate with many aspects of bat ecology. We hypothesized that atmospheric absolute humidity could explain global peak frequency variation directly and indirectly via increasing species body size and bat species richness. These hypotheses were tested using Bayesian phylogenetic path analysis on 226 tropical and subtropical bat species. In line with our predictions, we found a positive total effect of humidity on peak frequency, which was dominated by the positive indirect effects via body size and bat species richness. We did not observe the negative direct effect of humidity on peak frequency, which was hypothesized based on atmospheric attenuation of sound. In line with our expectations, excluding the predominantly clutter foraging bat families from our dataset downplayed the importance of the richness-mediated route. To conclude, our findings suggest that indirect effects, owing to ecology and biogeography of bat taxa, play a major role in the global relationship between peak frequency and atmospheric humidity.Peer reviewe

Atmospheric humidity affects global variation of bat echolocation via indirect effects

The peak frequency of bat echolocation is a species-specific functional trait linked to foraging ecology. It is tailored via evolution to suit conditions within the distribution range of each species, but the evolutionary drivers are not yet well-understood. Global patterns of humidity correlate with many aspects of bat ecology. We hypothesized that atmospheric absolute humidity could explain global peak frequency variation directly and indirectly via increasing species body size and bat species richness. These hypotheses were tested using Bayesian phylogenetic path analysis on 226 tropical and subtropical bat species. In line with our predictions, we found a positive total effect of humidity on peak frequency, which was dominated by the positive indirect effects via body size and bat species richness. We did not observe the negative direct effect of humidity on peak frequency, which was hypothesized based on atmospheric attenuation of sound. In line with our expectations, excluding the predominantly clutter foraging bat families from our dataset downplayed the importance of the richness-mediated route. To conclude, our findings suggest that indirect effects, owing to ecology and biogeography of bat taxa, play a major role in the global relationship between peak frequency and atmospheric humidity.Peer reviewe

Large-scale long-term passive-acoustic monitoring reveals spatio-temporal activity patterns of boreal bats

The distribution ranges and spatio-temporal patterns in the occurrence and activity of boreal bats are yet largely unknown due to their cryptic lifestyle and lack of suitable and efficient study methods. We approached the issue by establishing a permanent passive-acoustic sampling setup spanning the area of Finland to gain an understanding on how latitude affects bat species composition and activity patterns in northern Europe. The recorded bat calls were semi-automatically identified for three target taxa; Myotis spp., Eptesicus nilssonii or Pipistrellus nathusii and the seasonal activity patterns were modeled for each taxa across the seven sampling years (2015-2021). We found an increase in activity since 2015 for E. nilssonii and Myotis spp. For E. nilssonii and Myotis spp. we found significant latitude -dependent seasonal activity patterns, where seasonal variation in patterns appeared stronger in the north. Over the years, activity of P. nathusii increased during activity peak in June and late season but decreased in mid season. We found the passive-acoustic monitoring network to be an effective and cost-efficient method for gathering bat activity data to analyze spatio-temporal patterns. Long-term data on the composition and dynamics of bat communities facilitates better estimates of abundances and population trend directions for conservation purposes and predicting the effects of climate change

Northern Bat Eptesicus nilssonii (Keyserling and Blasius, 1839)

Peer reviewe

Atmospheric humidity affects global variation of bat echolocation via indirect effects

The peak frequency of bat echolocation is a species-specific functional trait linked to foraging ecology. It is tailored via evolution to suit conditions within the distribution range of each species, but the evolutionary drivers are not yet well-understood. Global patterns of humidity correlate with many aspects of bat ecology. We hypothesized that atmospheric absolute humidity could explain global peak frequency variation directly and indirectly via increasing species body size and bat species richness. These hypotheses were tested using Bayesian phylogenetic path analysis on 226 tropical and subtropical bat species. In line with our predictions, we found a positive total effect of humidity on peak frequency, which was dominated by the positive indirect effects via body size and bat species richness. We did not observe the negative direct effect of humidity on peak frequency, which was hypothesized based on atmospheric attenuation of sound. In line with our expectations, excluding the predominantly clutter foraging bat families from our dataset downplayed the importance of the richness-mediated route. To conclude, our findings suggest that indirect effects, owing to ecology and biogeography of bat taxa, play a major role in the global relationship between peak frequency and atmospheric humidity

Large-scale long-term passive-acoustic monitoring reveals spatio-temporal activity patterns of boreal bats

The distribution ranges and spatio-temporal patterns in the occurrence and activity of boreal bats are yet largely unknown due to their cryptic lifestyle and lack of suitable and efficient study methods. We approached the issue by establishing a permanent passive-acoustic sampling setup spanning the area of Finland to gain an understanding on how latitude affects bat species composition and activity patterns in northern Europe. The recorded bat calls were semi-automatically identified for three target taxa; Myotis spp., Eptesicus nilssonii or Pipistrellus nathusii and the seasonal activity patterns were modeled for each taxa across the seven sampling years (2015–2021). We found an increase in activity since 2015 for E. nilssonii and Myotis spp. For E. nilssonii and Myotis spp. we found significant latitude -dependent seasonal activity patterns, where seasonal variation in patterns appeared stronger in the north. Over the years, activity of P. nathusii increased during activity peak in June and late season but decreased in mid season. We found the passive-acoustic monitoring network to be an effective and cost-efficient method for gathering bat activity data to analyze spatio-temporal patterns. Long-term data on the composition and dynamics of bat communities facilitates better estimates of abundances and population trend directions for conservation purposes and predicting the effects of climate change.Peer reviewe

Large-scale long-term passive-acoustic monitoring reveals spatio-temporal activity patterns of boreal bats

Abstract The distribution ranges and spatio-temporal patterns in the occurrence and activity of boreal bats are yet largely unknown due to their cryptic lifestyle and lack of suitable and efficient study methods. We approached the issue by establishing a permanent passive-acoustic sampling setup spanning the area of Finland to gain an understanding on how latitude affects bat species composition and activity patterns in northern Europe. The recorded bat calls were semi-automatically identified for three target taxa; Myotis spp., Eptesicus nilssonii or Pipistrellus nathusii and the seasonal activity patterns were modeled for each taxa across the seven sampling years (2015–2021). We found an increase in activity since 2015 for E. nilssonii and Myotis spp. For E. nilssonii and Myotis spp. we found significant latitude -dependent seasonal activity patterns, where seasonal variation in patterns appeared stronger in the north. Over the years, activity of P. nathusii increased during activity peak in June and late season but decreased in mid season. We found the passive-acoustic monitoring network to be an effective and cost-efficient method for gathering bat activity data to analyze spatio-temporal patterns. Long-term data on the composition and dynamics of bat communities facilitates better estimates of abundances and population trend directions for conservation purposes and predicting the effects of climate change