Shoreline Foraging Activity by Gray Bats (Myotis grisescens) and Northern Long-eared Bats (Myotis septentrionalis) on Grand Lake, Oklahoma

Abstract

Shoreline foraging activity of the endangered gray bat (Myotis grisescens) and threatened northern long-eared bats (Myotis septrionalis) on Grand Lake, Oklahoma was assessed using acoustic sampling. Activity was surveyed in summer 2015 and 2016 along six mobile boat transects using Anabat acoustic detectors. Four transects using stationary detectors were also used in 2016. A total of 34,593 calls were detected for 9 bat species. The tri-colored bat (Perimyotis subflavus) and gray bat were the most frequent, combining to make up ≈ 90% of the total calls. The
gray bat was recorded in five of the six mobile routes with call abundance highest within 8 km of maternity caves, specifically Drowning Creek, Elk River, and Three Fingers Cove. In contrast, most calls on stationary transects were found on Duck Creek and Honey Creek. The northern long-eared bat was the least detected species, comprising <0.4% of the total calls. A single call was detected during mobile surveys, occurring in 2015 on the northern shore of Drowning Creek. Stationary transects were more successful with calls for this species with most calls found on Drowning
Creek and Honey Creek. In total, 293 locations were found to support foraging activity across nine species. More specifically, 48 locations were identified as foraging habitat for the two imperiled bat species (28 gray; 20 northern long-eared). Such spatial data provides the potential for identifying habitat factors needed for effective conservation for these species.