Determining nightly bat activity with, and sampling effectiveness of, modified NABat driving transects in urban areas

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Sarah A. Schimpp (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Matina Kalcounis-Rüppell

Abstract: Time of peak bat activity during the night differs among bat species. Foraging strategies may differ among species due to prey availability, habitat availability, and/or interactions between species. Habitat availability is altered in urban areas, which may affect insect prey availability and interspecies interactions. Monitoring changes in bat diversity and behavior associated with habitat conversion is important, but some traditional bat monitoring methods may not be appropriate for all study sites. Acoustic monitoring techniques, including mobile monitoring using driving transects, may be good alternatives to study nightly activity in urban bat populations. Acoustic monitoring is an important component of many monitoring programs including the North American Bat Monitoring Program (NABat). Driving transects that are approximately 25 to 48 kilometers long within 100 km2 grid cells are used by NABat, but choosing appropriate transect routes can be difficult in urban areas. Shorter transects could be used to alleviate sampling issues, but a modified protocol may be less effective at sampling some bat species. My objectives were to use mobile acoustic monitoring to determine when bat species are active in a single night in urban and non-urban sites, if nightly bat activity patterns in urban sites differ from nightly bat activity patterns in non-urban sites, and whether sampling using a modified mobile acoustic monitoring protocol with reduced transect lengths is effective compared to the standardized NABat protocol. I recorded bat echolocation calls using Anabat acoustic detectors while driving transects through the night at five sites (three “urban” and two “non-urban”) located in the Piedmont region of north-central North Carolina from May through August 2016. Transects were driven three times per night in each site starting 45 minutes, 180 minutes, and 300 minutes after sunset using a modified NABat protocol with 6 “short” transects (about 3.2 km long each). An additional “long” transect (about 25 km long, using NABat protocol) was sampled in 4 sites (two of the urban sites and both non-urban sites) starting 45 minutes after sunset. Recorded echolocation call sequences were analyzed manually using AnalookW and automatically using Bat Call Identification and Echoclass software. Total bat activity and Lasiurus borealis activity was decreased later in the night in urban sites. There were also fewer Eptesicus fuscus, Lasionycteris noctivagans, and Nycticeius humeralis calls on the latest time period. There were more E. fuscus, L. noctivagans, and Tadarida brasiliensis calls and fewer L. borealis, N. humeralis, and Perimyotis subflavus calls in urban sites than non-urban sites. Fewer short transects were needed to match the detection probability on long transects for E. fuscus, L. borealis, and P. subflavus, while more short transects were needed for L. noctivagans, N. humeralis, and T. brasiliensis. These results suggest that bats in urban areas partition time differently, which is important to consider as urbanization impacts bat populations. They also suggest that short transects can be used effectively for NABat sampling in urban areas.

Additional Information

Language: English
Date: 2017
Acoustic Monitoring, Bats, Echolocation, Urbanization
Bats $z North Carolina
Bats $x Detection
Bats $x Behavior
Bat sounds
Anabat bat detection systems

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