Bat sonar and wing morphology predict species vertical niche
Résumé
The use of echolocation allows insectivorous bats to access unique foraging niches by locating obstacles and prey with ultrasounds in complete darkness. To avoid interspecific competition, it is likely that sonar features and wing morphology co-evolved with species vertical distribution, but due to the technical difficulties of studying flight in the vertical dimension, this has never been demonstrated with empirical measurements.
We equipped 48 wind masts with arrays of two microphones and located the vertical distribution of a community of 19 bat species and two species groups over their annual activity period (> 8,000 nights). We tested the correlation between the proportion of flights at height and the acoustic features of bat calls as well as their wing morphology.
We found that call peak frequency and bandwidth are good predictors of bat use of the vertical space regardless of their acoustic strategies (i.e. gleaning, hawking or detecting prey flutter). High wing aspect ratios and high wing loadings were associated with high proportions of time spent at height, confirming hypothesis from the literature.
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