Date of Award
Level of Access Assigned by Author
Master of Science (MS)
Ecology and Environmental Sciences
Second Committee Member
Danielle L. Levesque
Third Committee Member
Additional Committee Members
In Maine, the decline of cave dwelling bats has been caused by the fungal disease commonly known as white-nose syndrome discovered in 2006. Northern long-eared bats (Myotis septentrionalis), little brown (Myotis lucifigus) andeastern tricolored bats (Perimyotis subflavus) have experienced 95% or greater population declines, and eastern small-footed (Myotis leibii) and big brown bats (Eptesicus fuscus) have also declined. In Maine, talus slopes, or piles of sloped rocks found at the base of cliffs, are widely distributed and past research has suggested talus as a potentially important, but previously unrecognized, class of hibernacula.
In Chapter 1, We collected passive ultrasonic acoustic recordings of bats during the Core Winter Period (December-February) at 43 talus slopes over two winters in Maine from 2017-2019, and performed a single-season occupancy analyses to evaluate the characteristics associated with detection and site presence. We found 34% of sites were occupied by Myotis spp. (Ψ = 0.337 ± SE 0.074) with a nightly detection probability of 6% (p =0.062 ± SE 0.008). We found 30% of sites were occupied by little brown bats (Ψ = 0.307 ± SE 0.092) with a nightly detection probability of 2% (p = 0.024 ± SE 0.006). We found 17% of sites were occupied by eastern small-footed bats (Ψ = 0.172± SE .06) with a nightly detection probability of 5% (p = 0.051± SE 0.01). We found 58% of sites were occupied by big brown bats (Ψ = 0.584 ± SE 0.076) with a nightly detection probability of 12% (p = 0.117 ± SE 0.008). We found 9% of sites were occupied by northern long-eared bats. The mean occupancy of northern long-eared bats based on an intercept-only model was Ψ = 0.333 (± SE 0.315), with an estimated nightly detection probability of 5% (p = 0.005 ± SE .005). We provide information about site characteristics likely to predict bat presence at talus slopes during the winter period and suggest future work should evaluate whether the predictive value of these site characteristics hold true for other talus areas in Maine or eastern North America.
In Chapter 2, we assessed the use of passive ultrasonic acoustic receivers to determine bat presence on talus slopes during the winter, but information is lacking on appropriate acoustic sampling protocols during this time period. We used a network of passive ultrasonic acoustic receivers deployed during the Core Winter Period, we evaluated what is the minimum number of nights a detector needs to be deployed to determine species’ presence with a high degree of certainty. We found that placing four detectors on a talus slope for 8-45 nights (depending on species) provides ≥ 95% confidence in detecting activity of little brown bats, eastern small footed bats, and big brown bats, given they were present at the site. Chapter 2 provides guidance to state and federal agencies as well as private landowners to better understand the presence of bats on the winter landscape at talus slopes.
Heilakka, Christopher C., "Do Talus Slopes Provide Hibernacula Resources for Bats in Maine? Site Charecteristics Associated With Winter Occupancy and Sampling Design" (2023). Electronic Theses and Dissertations. 3867.