Patterns of Acoustical Activity of Bats Prior to and Following White-Nose Syndrome Occurrence

Abstract

White-nose Syndrome (WNS), a wildlife health concern that has decimated cave-hibernating bat populations in eastern North America since 2006, began affecting source-caves for summer bat populations at Fort Drum, a U.S. Army installation in New York in the winter of 2007–2008. As regional die-offs of bats became evident, and Fort Drum's known populations began showing declines, we examined whether WNS-induced change in abundance patterns and seasonal timing of bat activity could be quantified using acoustical surveys, 2003–2010, at structurally uncluttered riparian–water habitats (i.e., streams, ponds, and wet meadows). As predicted, we observed significant declines in overall summer activity between pre-WNS and post-WNS years for little brown bats Myotis lucifugus, northern bats M. septentrionalis, and Indiana bats M. sodalis. We did not observe any significant change in activity patterns between pre-WNS and post-WNS years for big brown bats Eptesicus fuscus, eastern red bats Lasiurus borealis, or the small number of tri-colored bats Perimyotis subflavus. Activity of silver-haired bats Lasionycteris noctivagans increased from pre-WNS to post-WNS years. Activity levels of hoary bats Lasiurus cinereus significantly declined between pre- and post-WNS years. As a nonhibernating, migratory species, hoary bat declines might be correlated with wind-energy development impacts occurring in the same time frame rather than WNS. Intraseason activity patterns also were affected by WNS, though the results were highly variable among species. Little brown bats showed an overall increase in activity from early to late summer pre-WNS, presumably due to detections of newly volant young added to the local population. However, the opposite occurred post-WNS, indicating that reproduction among surviving little brown bats may be declining. Our data suggest that acoustical monitoring during the summer season can provide insights into species' relative abundance on the landscape as affected by the occurrence of WNS.

Disease and community structure: white‐nose syndrome alters spatial and temporal niche partitioning in sympatric bat species

“…While some small successional change in forested environments did occur over the course of our 8‐year study, the habitat conditions within the riparian areas where we focused our study were relatively unchanged. Development was spatially concentrated in the south‐eastern corner of the installation, with the remainder of the installation consisting of 18 training areas, an airfield and a large, centralized ordnance impact zone that are all largely undeveloped (Dobony et al ., ; Ford et al ., ).…”

“…Nine bat species have been documented on Fort Drum, including: MYLU, MYSO, MYSE , MYLE, silver‐haired bat ( Lasionycterius noctivagans , LANO), PESU, EPFU, eastern red bat ( Lasiurus borealis , LABO) and hoary bat ( Lasiurus cinereus , LACI). During the winter of 2007–2008, WNS appeared in area hibernacula, resulting in mass overwinter mortality and dramatic declines in summer activity by at least 3 of the most commonly encountered bat species (MYLU, MYSE and MYSO) since 2008 (Ford et al ., ). In particular, MYLU suffered a precipitous population decline post‐WNS (Dobony et al ., ; Ford et al ., ).…”

“…We downloaded, identified and tallied the number of species identifications per hour for each site on each sample night (see Ford et al ., for specific echolocation pass identification methodologies). The resulting echolocation tallies commonly are used as an index of bat activity that in turn serves as a surrogate for bat relative abundance (Hayes, ; Law & Chidel, ; Gehrt & Chelsvig, ; Owen et al ., ).…”

Interannual Survival ofMyotis lucifugus(Chiroptera: Vespertilionidae) near the Epicenter of White-Nose Syndrome

“…By early 2009, WNS had been documented at most hibernacula throughout the Northeast, causing precipitous declines in wintering populations of Myotis lucifugus (LeConte) (Little Brown Myotis) (Frick et al 2010a, Langwig et al 2012). Acoustic monitoring indicated that activity of Little Brown Myotis on the summer landscape also decreased over 70% after arrival of WNS (Brooks 2011, Dzal et al 2011, Ford et al 2011). Accordingly, most summer colonies in the area also declined dramatically in size (e.g., Frick et al 2010b, Fuller et al 2012).…”

Prevalence and phenology of white-nose syndrome fungus Pseudogymnoascus destructans in bats from Poland

“…Also rare and endangered species, like Myotis sodalis, suffer from the disease [15], and strong decrease in activity of Myotis spp. during summer was recorded in the areas surrounding underground roosts affected by WNS [16].…”