Occupancy and activity patterns of a newly white-nose syndrome infected species in Texas, the Tricolored Bat (Perimyotis subflavus).

Abstract

Perimyotis subflavus was once a common and widely distributed species of bat in the United States before white-nose syndrome (WNS) caused devastating population-level declines. The species has now been recommended for listing as federally endangered, although the ruling has not yet been finalized. Though WNS was discovered in the United States in 2006, Texas is currently at the leading edge of the expansion of the disease into the southwest. The first documentation of WNS occurred in Texas in 2020, when a die-off of Myotis velifer occurred; in 2024, WNS was detected on P. subflavus in Texas. To better manage populations of P. subflavus across Texas, it is imperative to fill knowledge gaps regarding seasonal distribution and activity of the species across the state, as well as habitat associations. Thus, our objectives were to assess the influence of weather and landcover on: (i) seasonal occupancy; (ii) nightly activity; (iii) hourly activity; (iv) the log-odds of a call being from P. subflavus if any bat was acoustically active; and (v) to examine diel activity patterns among seasons and Ecoregions. Activity varied by season and Ecoregion. Broadly, results suggest landcover-particularly forest (positive), wetland (positive), and urban (negative)-influenced occupancy probability, whereas weather more greatly influenced activity. Generally, activity was positively influenced by temperature, negatively influenced by wind speed and precipitation, and the effects of humidity varied seasonally. The log-odds of a call being P. subflavus given that any bat was acoustically active followed a similar pattern to overall activity. Results confirm widespread distribution of P. subflavus across Texas as well as provide baseline information on the influences of landscape characteristics and weather on activity for the 3-year period of 2020 to 2023, just prior to the first WNS detection for this species in this state.