Article impact statement: Data sharing and coordinated monitoring are needed to assess species' response to threats to inform conservation planning at relevant scales.

Cooling historically unimportant hibernacula provides bats with critical habitat and is an important tool for combating whitenose syndrome.

Infectious diseases caused by invasive, environmentally persistent fungal pathogens have increasingly endangered global biodiversity, yet disease management remains a major conservation challenge. A prominent example is white‐nose syndrome (WNS), a disease caused by the invasive fungal pathogen Pseudogymnoascus destructans (Pd) that has devastated populations of multiple North American bat species, but for which few effective management tools exist. Here, we propose that strategies to delay environmental transmission of Pd during early winter could limit WNS disease effects across winter, benefitting bats. We used a small captive experiment and a multi‐year field trial on wild, free‐ranging bats to assess an environmental control strategy to manage Pd within its environmental reservoir in Pennsylvania, USA, where the pathogen has become endemic. The strategy centers on the application of Polyethylene Glycol 8000 (PEG) to roost substrates in summer, prior to bat hibernation, as a means to disrupt environmental transmission to bats in early winter. In the captive experiment, environmental transmission of Pd to immunologically naïve little brown myotis (Myotis lucifugus) occurred from roost substrates inoculated with Pd, but the application of PEG to these substrates effectively blocked this transmission. In the field trial, Pd load and infection extent both declined substantially in free‐ranging M. lucifugus after treatment relative to controls, with declines exceeding effects of inter‐site and inter‐annual variation. Pathogen prevalence and load also declined substantially after PEG treatment in big brown bats (Eptesicus fuscus). No negative effects of PEG treatment were observed in body condition or colony counts of bats or in the microbial community. Together, these results are consistent with effective environmental control of Pd and reduced WNS disease effects in bats within contaminated hibernacula. The results also highlight the potential of carefully designed environmental control strategies for managing environmentally persistent pathogens.

Invasive pathogens threaten wildlife health and biodiversity. Physiological responses of species highly susceptible to pathogen infections following invasion are well described. However, the responses of less susceptible species (relative to highly susceptible species) are not well known. Latitudinal gradients, which can influence body condition via Bergmann's rule and/or reflect the time it takes for an introduced pathogen to spread geographically, add an additional layer for how mammalian species respond to pathogen exposure. Our goal was to understand how hosts less susceptible to pathogen infections respond to long-term pathogen exposure across a broad latitudinal gradient.We examined changes in body mass throughout pathogen exposure time across the eastern United States (latitude ranging 30.5 N-44.8 N) in Eptesicus fuscus, a bat species classified as less susceptible to infection (relative to highly susceptible species) by the invasive fungal pathogen that causes white-nose syndrome, Pseudogymnoascus destructans (Pd). Using 30 years of spring through fall adult capture records, we created linear mixed-effects models for female and male bats to determine how mass or mass variation changed across the eastern United States from pre-Pd invasion years through Pd invasion (0-1 years with Pd), epidemic (2-4 years with Pd), and established years (5+ years with Pd). By Pd establishment, all female and male bats decreased body mass with increasing latitude across a spatial threshold at 39.6 N.Differences in bat mass north and south of the spatial threshold progressively increased over Pd exposure time-steps such that body mass was lower in northern latitudes compared to southern latitudes by Pd establishment.Results indicated that the progressive differences in E. fuscus body mass with latitude across the eastern United States are due to long-term pathogen exposure; however, other environmental and ecological pressures may contribute to decreases in E. fuscus body mass with latitude and long-term pathogen exposure. As pathogen introductions and emerging infectious diseases become

The decline in northern myotis (Myotis septentrionalis) populations due to the disease white-nose syndrome (WNS) has led to the species receiving federal protection in the United States and Canada, requiring conservation of critical habitats. However, considerably more is known about summer habitat preferences of northern myotis compared to late summer through winter. Our goal was to describe the seasonal presence and habitat use of a remnant colony of northern myotis in central Pennsylvania. We radio-tagged 31 northern myotis and established 6 acoustic monitoring stations to document activity from 2017–2021. We found that roost trees used during the maternity season by reproductive females were occupied by bats during both summer (21 June–14 August) and autumn (15 August–31 October), indicating similar habitat use patterns between seasons. During this time, both males and females preferred to roost in dead and declining trees. No other variable influenced male use, but females also preferred trees located close to water and in forest stands with higher basal area than randomly located trees. Northern myotis with active transmitters never left the study area and were tracked to roosts until early November. During October and November, a female and male were tracked to an underground network of air-filled voids (the Milieu Souterrain Superficiel) we presume to be a hibernaculum. Northern myotis calls were recorded outside this roost between March and October, and bats were observed emerging from this roost during spring and autumn but not summer. Acoustic activity at this site exhibited a seasonal pattern that differed from acoustic activity near roost trees and foraging areas, with a peak of activity during late summer when northern myotis are known to swarm. These data show that northern myotis maternity roosts are used extensively outside of summer and may be vulnerable to forestry practices that occur even outside of the pup-rearing season. These data also support the growing evidence that some northern myotis hibernate outside of caves and mines.