# Capture rates of Eptesicus fuscus increase following white‐nose syndrome across the eastern US

## TL;DR

Big brown bat capture rates increased after white-nose syndrome spread, with females showing greater changes than males.

## Contribution

The study reveals demographic shifts in a persisting bat species following a fungal disease invasion.

## Key findings

- Capture rates of Eptesicus fuscus increased after Pd establishment, especially in females.
- Pregnant and post-lactating females showed the largest increases in capture rates.
- Changes may be due to foraging behavior, abundance, or reproductive cycle shifts.

## Abstract

Emerging infectious diseases threaten wildlife globally. While the effects of infectious diseases on hosts with severe infections and high mortality rates often receive considerable attention, effects on hosts that persist despite infection are less frequently studied. To understand how persisting host populations change in the face of disease, we quantified changes to the capture rates of Eptesicus fuscus (big brown bats), a persisting species susceptible to infection by the invasive fungal pathogen Pseudogymnoascus destructans (Pd; causative agent for white‐nose syndrome), across the eastern US using a 30‐year dataset. Capture rates of male and female E. fuscus increased from preinvasion to pathogen establishment years, with greater increases to the capture rates of females than males. Among females, capture rates of pregnant and post‐lactating females increased by pathogen establishment. We outline potential mechanisms for these broad demographic changes in E. fuscus capture rates (i.e., increases to foraging from energy deficits created by Pd infection, increases to relative abundance, or changes to reproductive cycles), and suggest future research for identifying mechanisms for increasing capture rates across the eastern US. These data highlight the importance of understanding how populations of persisting host species change following pathogen invasion across a broad spatial scale. Understanding changes to population composition following pathogen invasion can identify broad ecological patterns across space and time, and open new avenues for research to identify drivers of those patterns.

To understand how persisting host populations change in the face of disease, we quantified changes to the capture rates of Eptesicus fuscus (big brown bats), a species that is annualy exposed and infected by the invasive fungal pathogen Pseudogymnoascus destructans (Pd); causative agent for white‐nose syndrome), using a 30‐year dataset across the eastern US. Here, the overall capture rates of adult E. fuscus increased from preinvasion to Pd establishment years across the eastern US. In conclusion, our work highlights the need to better understand how host populations change across broad spatial scales with continued pathogen exposure.