Flying by the river side: Survey of bat distributions and environmental contexts along a 1000-mile river corridor, Green and Colorado Rivers, USA

Aim

Emerging research shows how bioindicators, specifically bats, can serve as a means for monitoring conservation and management of riparian corridors for multiple taxonomic groups. To track changes in the composition or abundance of bioindicator species, researchers must attain a baseline in species presence and relative activity. We examined the spatial and temporal patterns of bat community composition and activity along a 1000-mile river corridor to determine species diversity trends by latitude and habitat.

Location

Colorado River Basin.

Methods

Here we describe the results from an acoustic bat survey conducted opportunistically on the 2019 Sesquicentennial Colorado River Exploring Expedition. This broad, 1000-mile survey provides a baseline for species distributions over a large geographic range.

Results

In total, we collected 63 nights of acoustic data over 70 days and recorded over 59,000 files equating to 45,363 caLL files (≥2 pulses). 18,490 (41% of caLL files) were identified as species (n = 19 bat species). We applied non-metric multidimensional scaling to characterize spatiotemporal patterns of activity between species, as well as compared bat activity among river features and local environmental conditions (i.e., temperature and time since sunset) using an information theoretic approach.

Conclusion

Species composition varied by physiographic region and adjacent river habitat, thus providing a quantifiable measure of determining habitat quality along this major river system and providing baseline information for using bats as bioindicators of habitat quality.