Natural Behaviours of Echolocators, with an Emphasis on Vespertilionid Bats

Here I report on two experimental studies and one observational analysis addressing the flexibility and ecological limitations of sensorimotor integration in echolocating mammals, as they relate to sensory ecology and foraging behaviour. In chapter two, I use acoustic data to comparatively assess echolocation and motor activities of bats and toothed whales to test (i) how the presence of a conspecific influences the spectral and temporal content of echolocation signals and (ii) whether these species behave similarly when foraging with a conspecific. The results suggest that in the presence of conspecifics (i) both bats and toothed whales exhibit the Lombard effect, and (ii) bats additionally employ subsets of both a Jamming Avoidance Response and a clutter response. Behaviourally, only porpoises appear to modify their beam direction. In chapter three, I use acoustic, photo, and video data to compare the developmental trajectories of (i) flight attempts, (ii) wing morphology, and (iii) vocalizations of big brown bat pups in the context of landing behavior, specifically with respect to landing buzz production. The results (i) clarified previous studies exploring pup vocal and flight ontogeny and (ii) identified developmental relationships between wing morphology (RWL) and flight milestones. In chapter four, I comparatively assess acoustic recordings of bat activity before and after the introduction of white-nose syndrome (WNS) to South Eastern Ontario to explore the effects of WNS on (i) species abundance and (ii) habitat use. I also explore (iii) the possibility of niche release and realized niche expansion due to reduced interspecific competition resulting from species-specific WNS susceptibility. The results confirm that (i) endangered species are detected less often foraging in open field habitats since the introduction of WNS, and that (ii) relatively unaffected species have increased their presence (but not active foraging) in clutter/edge and open field habitats. The results also indicate that (iii) over water habitats showed no difference between pre- and post-WNS bat activity, suggesting that niche expansion for relatively unaffected species may be limited to some habitats and not others.Ph.D