Effect of passive acoustic sampling methodology on detecting bats after declines from white nose syndrome

Abstract

Concomitant with the emergence and spread of white-nose syndrome (WNS) and precipitous decline of many bat species in North America, natural resource managers need modified and/or new techniques for bat inventory and monitoring that provide robust occupancy estimates. We used Anabat acoustic detectors to determine the most efficient passive acoustic sampling design for optimizing detection probabilities of multiple bat species in a WNS-impacted environment in New York, USA. Our sampling protocol included: six acoustic stations deployed for the entire duration of monitoring as well as a 4 x 4 grid and five transects of 5-10 acoustic units that were deployed for 6-8 night sample durations surveyed during the summers of 2011-2012. We used Program PRESENCE to determine detection probability and site occupancy estimates. Overall, the grid produced the highest detection probabilities for most species because it contained the most detectors and intercepted the greatest spatial area. However, big brown bats (Eptesicus fuscus) and species not impacted by WNS were detected easily regardless of sampling array. Endangered Indiana (Myotis sodalis) and little brown (Myotis lucifugus) and tri-colored bats (Perimyotis subflavus) showed declines in detection probabilities over our study, potentially indicative of continued WNS-associated declines. Identification of species presence through efficient methodologies is vital for future conservation efforts as bat populations decline further due to WNS and other factors.

Investigating maternity roost selection by northern long-eared bats at three sites in Wisconsin

“…Furthermore, temporal differences in female MYSE roosting behavior, i.e. number of bats within a roost and rates of roost-switching, throughout the maternity season have been demonstrated in previous studies (Garroway & Broders 2008, Silvis et al 2012, 2014. However, within the context of Wisconsin, the phenology would be largely the same, and our data collection took place within the confines of the time period when maternity colonies would be intact in June and July prior to fall migration and colony dispersal.…”

“…Comparing used roost tree parameters with both selected and random available roost trees is accepted as a valid method to assess evidence regarding which characteristics of trees are associated with roost selection (Silvis et al 2012, 2014, Clement & Castleberry 2013. We used an information theoretic approach (IT) coupled with conditional logistic regression (Therneau & Grambsch 2000) to compare individual roost tree characteristics to the 4 nearest neighboring and available trees (Anderson & Burnham 2002, Silvis et al 2012.…”

“…Historically, the northern long-eared bat Myotis septentrionalis (Trouessart, 1897) (hereafter MYSE) was among the most common bat species in North America, distributed across 37 eastern and northcentral US states, and in several Canadian provinces from the Atlantic coast to the Northwest Territories (Caceres & Barclay 2000). The distribution of bats in eastern North America pre-and post-WNS, including MYSE, are affected by a variety of site-and landscape-level factors, including availability of prey, level of habitat fragmentation, and climate (Ford et al 2006a, Silvis et al 2012, Coleman et al 2014, Pauli et al 2015. MYSE can be found throughout Wisconsin and adjacent portions of the Upper Midwest, although the species is less common in the Upper Midwest relative to other portions of its range (Francl 2008).…”

Peer Review #2 of "Mobile acoustic transects miss rare bat species: implications of survey method and spatio-temporal sampling for monitoring bats (v0.1)"

“…Similarly, spatial heterogeneity can lead to different estimates of bat activity and species richness, even among acoustic detectors located within the same vegetation stand (Britzke 2003;Duchamp et al 2006;Fischer et al 2009;Froidevaux et al 2014). Recommendations for duration and spatial stratification of surveys have varied widely PeerJ reviewing PDF | ( 2017:04:17763:1:1:REVIEW 16 Aug 2017) Manuscript to be reviewed among studies (Bean & Rowland 1997;Britzke et al 2013;Coleman et al 2014;Froidevaux et al 2014;Rodhouse et al 2011;Stahlschmidt & Brühl 2012). Two primary acoustic survey methods are frequently recommended for use in bat monitoring protocols: stationary acoustic point surveys (hereafter 'stationary surveys'), and mobile acoustic driving transect surveys (hereafter 'mobile transects') (e.g., North American Bat Monitoring Program (NABat); (Loeb et al 2015).…”

Peer Review #1 of "Mobile acoustic transects miss rare bat species: implications of survey method and spatio-temporal sampling for monitoring bats (v0.1)"

“…Manuscript to be reviewed among studies (Bean & Rowland 1997;Britzke et al 2013;Coleman et al 2014;Froidevaux et al 2014;Rodhouse et al 2011;Stahlschmidt & Brühl 2012).…”