IMPACTS OF TROUT INTRODUCTION ON BAT ACTIVITY AT HIGH-ELEVATION LAKES IN THE SIERRA NEVADA.
Mary K. Clapp; UC-Davis; 1306 L St, Davis, CA, 95616; (301) 471-7949; mkclapp@ucdavis.edu; Madison K. Boynton, Leila S. Harris, Gail L. Patricelli
Beginning in the late 1800s, land managers introduced trout to the majority of the Sierra Nevada's historically fishless high-elevation watershed to promote recreational angling. Most studies on the impacts of these introductions have focused on aquatic ecosystems and revealed a starkly lower relative abundance and diversity of most macroinvertebrate groups at fish-containing lakes, but much less is known about the effects on terrestrial consumers of these emerging insects. We investigated bats' use of high-elevation (>3000m) lakes as a source of highly profitable prey, predicting that bats are more active at fishless lakes where macroinvertebrate abundance is greater. In summer 2014, we collected nighttime acoustic recordings of bats at 3 pairs of fish-containing and fishless lakes in Sequoia-Kings Canyon National Park. We identified bats to acoustic clade using Sonobat and report on diel and seasonal timing of bat activity at high-elevation lakes and bat activity with respect to fish presence using GLMs. Contrary to our predictions, call activity of high-frequency bats were more numerous at fish-containing lakes, corroborating the results of the only other study done to date on impacts of introduced trout on bat activity. We discuss various limitations of acoustic data and suggest that future work include in-person surveys and diet estimation to more robustly describe patterns in calling activity with bat abundance and feeding patterns.
Ecology and Conservation of Bats II   Student Paper