1. Profiling Bat Species Presence in Managed Wildlife Landscapes
*Maggie Aduddell Hunt1 and Thomas C. McElroy1
1. Department of Ecology, Evolution and Organismal Biology, Kennesaw State University, GA
Abstract
Hypothesis and Objectives
Results continued
Restoration of endemic flora or reintroduction of at-risk fauna may include methods that also affect the activity of other wildlife. Bats inhabit key ecological niches in several ecosystems and are often considered indicators of ecosystem health. We investigated the effect of forest management history and current management practices on bat species presence and activity. Passive acoustic monitoring was performed concurrently for two wildlife management areas in the Raccoon Creek Watershed of northwest Georgia, USA, that differ in landscape management histories and current long leaf pine restoration practices. Our preliminary results indicate a difference in species presence and activity between regions that differ in landscape management histories, but no significant differences among contemporary restoration practices.
1) Measure the effectiveness of restoration methods as a function of bat species presence and activity levels via acoustic surveys.
2) Quantify variation in the composition of resources such as canopy density and prey abundance among studied habitat areas.
3) Establish baseline data for the landscape over several monitoring periods.
Table 2. Analysis of variance on site and treatment.
Source
D.F.
Mean Square
F-value
P-value
Model 3
40.09
0.08
0.987
Error 20
875.84 --
Corrected total 23
Site 1
69.64
0.781
Treatment
22.96
0.03
0.873
Site*Treatment
27.67
0.861
Table 1. Two-sample t-tests by site and treatment.
Mean
D.F.
T-Stat
Pr >|t|
PAULDING
34.45 10
0.55
0.5951
SHEFFIELD
25.31
CONTROL
30.43
-0.07
0.9480
BURN
29.31
Experimental Methods
Acoustic surveys: Passive acoustic monitoring was performed June 2016 to October 2016 within the Sheffield WMA and Paulding WMAs. Wildlife Acoustics® SM3BAT units were deployed for at least four consecutive nights at sampling locations. Two sampling sites within each wildlife management area – a control and a treated site – were sampled simultaneously for each deployment. Detector microphones were secured at least 3m from the ground, and default programming for sunset to sunrise recording was used. A total of three sampling periods were completed, with a total of six sampling locations sampled.
Data Processing: Wildlife Acoustics® Kaleidoscope Pro was used for batch processing of raw data and auto-identification of bat species. The software removes noise and low quality files through scrubbing, leaving behind bat passes with a species auto-ID label. Species identification of call sequences are performed by computer algorithms that automatically build classifiers from a large library of pre-labeled, both full-spectrum and zero-crossing recording, files3.
Data Analysis: We analyzed post-scrubbed files as separate bat passes, with a bat pass defined as a call sequence of ≥2 pulses without an interruption of >5 seconds. Activity levels were determined via per night means of bat passes and pulses recorded. ANOVA analysis was performed to test for differences in bat activity levels between samples. Species presence was determined after limited manual confirmation of auto-ID labels; only labels with a discriminant probability threshold of ≥0.70 for this round of data analysis. A chi-square analysis was performed to test for relatedness between species presence, restoration treatment, and land management history.
CHISQR:
P =
Figure 1. Montane longleaf pine habitat within the Sheffield Wildlife Management Area property in Paulding County, Georgia, USA.
Background
Longleaf pine woodlands are among the most biodiverse communities in temperate North America, and provide habitat for many endemic biota and specialist species1. By restoring remnant longleaf pine habitat, wildlife management agencies hope to reintroduce and maintain the biodiversity associated with longleaf pine landscapes.
Few studies have explored the effects management of pine forests have on small mammals, such as bats2. Documenting bat species presence and activity during longleaf pine restoration could indicate if these methods increase activity levels and biodiversity for taxa such as small mammals.
The focal study sites are located in state-owned, intensively-managed longleaf restoration landscapes. The Sheffield WMA represents restoration from historically natural timber landscape; the Paulding Forest WMA represents restoration from landscape more recently used for logging and timber harvest.
CHISQR:
P =
Results
Figure 4. Species presence by region, or land management history, and by restoration treatment (C = Control; B = Burned for restoration).
Discussion and Future Work
No significant differences were found in bat activity levels between control and prescribed burn areas, nor between landscape management histories. The only significant differences between bat activity levels were temporal, which was to be expected based on past literature. There were significant differences among species presence between land management histories, but not between control and prescribed burn areas overall. This was a preliminary data analysis; more involved analysis of bat activity levels based on variables such as site and treatment cycle variation is being performed. Further manual confirmation of bat species auto-identification labels provided by Wildlife Acoustics® Kaleidoscope Pro will be pursued and may change species presence as well as quality bat pass data. Future work will include multivariate analysis of other data variables collected, such as weather conditions, canopy density measurements, and prey abundance counts for sampling sites.
Figure 3. Table of mean bat passes per night for each wildlife management area sampled.
Figure 2. Sheffield WMA and Paulding Forest WMA properties in Paulding County, GA.
Acknowledgments
We thank Megan Morrison, Melissa Palacios, Adam Dean, and Nick Collini, undergraduate research assistants at KSU.
We thank Brent Womack, DNR biologist for the study area, and Trina Morris, DNR bat biologist, for consultation.
Funding was received from Kennesaw State University, College of Science and Mathematics.
Literature Cited
Outcalt, Kenneth W “The Longleaf Pine: Ecosystem of the South.” Native Plants Journal. Indiana University Press. 1 (1):
Greene, Rachel E., Raymond B. Iglay, Kristine O. Evans, Darren A. Miller, T. B. Wigley, and Sam K. Riffell “A meta-analysis of biodiversity responses to management of southeastern pine forests—opportunities for open pine conservation.” Forest Ecology and Management 360: 30-9.
Agranat, Ian “Bat Species Identification from Zero Crossing and Full Spectrum Echolocation Calls using HMMs, Fisher Scores, Unsupervised Clustering and Balanced Winnow Pairwise Classifiers.” Wildlife Acoustics, Inc.