Long-term changes in occurrence, relative abundance, and reproductive fitness of bat species in relation to arrival of White-nose Syndrome in West Virginia, USA

White-nose syndrome (WNS) is a disease caused by the fungus
Pseudogymnoascus destructans which has resulted in the deaths of millions
of bats across eastern North America. To date, hibernacula counts have
been the predominant means of tracking the spread and impact of this
disease on bat populations. However, an understanding of the impacts of
WNS on demographic parameters outside the winter season is critical to
conservation and recovery of bat populations impacted by this disease. We
used long-term monitoring data to examine WNS-related impacts to summer
populations in West Virginia, where WNS has been documented since 2009.
Using capture data from 290 mist-net sites surveyed from 2003–2019 on the
Monongahela National Forest, we estimated temporal patterns in presence
and relative abundance for each bat species. For species that exhibited a
population-level response to WNS, we investigated post-WNS changes in
adult female reproductive state and body mass. Myotis lucifugus (little
brown bat), M. septentrionalis (northern long-eared bat), and Perimyotis
subflavus (tri-colored bat) all showed significant decreases in presence
and relative abundance during and following the introduction of WNS, while
Eptesicus fuscus (big brown bat) and Lasiurus borealis (eastern red bat)
responded positively during the WNS invasion. Probability of being
reproductively active was not significantly different for any species,
though a shift to earlier reproduction was estimated for E. fuscus and M.
septentrionalis. For some species, body mass appeared to be influenced by
the WNS invasion, but the response differed by species and reproductive
state. Results suggest that continued long-term monitoring studies,
additional research into impacts of this disease on the fitness of WNS
survivors, and a focus on providing optimal non-wintering habitat may be
valuable strategies for assessing and promoting recovery of WNS-affected
bat populations.