Cooling of bat hibernacula to mitigate white-nose syndrome.

White-nose syndrome (WNS) is a fungal disease that has caused precipitous declines in several North American bat species, creating an urgent need for conservation. We examined how microclimates and other characteristics of hibernacula have affected bat populations following WNS-associated declines and evaluated whether cooling of warm, little-used hibernacula could benefit bats. During the period following mass mortality (2013-2020), we conducted 191 winter surveys of 25 unmanipulated hibernacula and 6 manipulated hibernacula across Pennsylvania (USA). We joined these data with additional datasets on historical (pre-WNS) bat counts and on the spatial distribution of underground sites. We used generalized linear mixed models and model selection to identify factors affecting bat populations. Winter counts of Myotis lucifugus were higher and increased over time in colder hibernacula (those with midwinter temperatures of 3-6 °C) compared with warmer (7-11 °C) hibernacula. Counts of Eptesicus fuscus, Myotis leibii, and Myotis septentrionalis were likewise higher in colder hibernacula (temperature effects = -0.73 [SE 0.15], -0.51 [0.18], and -0.97 [0.28], respectively). Populations of M. lucifugus and M. septentrionalis increased most over time in hibernacula surrounded by more nearby sites, whereas Eptesicus fuscus counts remained high where they had been high before WNS onset (pre-WNS high count effect = 0.59 [0.22]). Winter counts of M. leibii were higher in hibernacula with high vapor pressure deficits (VPDs) (particularly over 0.1 kPa) compared with sites with lower VPDs (VPD effect = 15.3 [4.6]). Counts of M. lucifugus and E. fuscus also appeared higher where VPD was higher. In contrast, Perimyotis subflavus counts increased over time in relatively warm hibernacula and were unaffected by VPD. Where we manipulated hibernacula, we achieved cooling of on average 2.1 °C. At manipulated hibernacula, counts of M. lucifugus and P. subflavus increased over time (years since manipulation effect = 0.70 [0.28] and 0.51 [0.15], respectively). Further, there were more E. fuscus where cooling was greatest (temperature difference effect = -0.46 [SE 0.11]), and there was some evidence there were more P. subflavus in hibernacula sections that remained warm after manipulation. These data show bats are responding effectively to WNS through habitat selection. In M. lucifugus, M. septentrionalis, and possibly P. subflavus, this response is ongoing, with bats increasingly aggregating at suitable hibernacula, whereas E. fuscus remain in previously favored sites. Our results suggest that cooling warm sites receiving little use by bats is a viable strategy for combating WNS.

El síndrome de nariz blanca (SNB) es una enfermedad fúngica que ha causado declinaciones precipitadas en varias especies de murciélagos norteamericanos, creando una necesidad urgente por conservarlas. Analizamos cómo los microclimas y otras características de los hibernáculos han afectado a las poblaciones de murciélagos después de declinaciones asociadas al SNB y evaluamos si el enfriamiento de hibernáculos cálidos con poco uso podría beneficiar a los murciélagos. Durante el periodo posterior a una mortalidad masiva (2013 - 2020), realizamos 191 censos invernales en 25 hibernáculos sin manipulación y en seis hibernáculos manipulados localizados en Pensilvania (EUA). Juntamos estos datos con conjuntos adicionales de datos de los conteos históricos (previos WNS) de murciélagos y de la distribución espacial de sitios subterráneos. Usamos modelos mixtos lineales generalizados y selección de modelos para identificar los factores que afectan a las poblaciones de murciélagos. Los conteos invernales de Myotis lucifugus fueron más altos e incrementaron con el tiempo en los hibernáculos fríos (aquellos con temperaturas de 3 - 6° C registradas a mitad del invierno) en comparación con los hibernáculos cálidos (7 - 11° C). Los conteos Eptesicus fuscus, M. leibii, y M. septentrionalis fueron igualmente más altos en los hibernáculos fríos (efectos de la temperatura = -0.73 [ES 0.15], -0.51 [0.18], y -0.97 [0.28], respectivamente). Las poblaciones de M. lucifugus y M. septentrionalis fueron las que más incrementaron con el tiempo en los hibernáculos rodeados por más sitios cercanos, mientras que los conteos de E. fuscus permanecieron altos en donde ya habían sido altos antes del comienzo del SNB (el efecto del conteo alto previo al SNB = 0.59 [0.22]). Los conteos invernales de M. leibii fueron más altos en los hibernáculos con altos déficits de presión de vapor (DPV) (particularmente por encima de los 0.1 kPa) en comparación con los sitios con un DPV menor (efecto del VPD = 15.3 [4.6]). Los conteos de M. lucifugus y E. fuscus también fueron más altos en donde el DPV era alto. Al contrario, los conteos de Perimyotis subflavus incrementaron con el tiempo en hibernáculos relativamente cálidos y no se vieron afectados por el DPV. En donde alcanzamos un promedio de enfriamiento de 2.1° C de los hibernáculos, los conteos de M. lucifugus y P. subflavus incrementaron con el tiempo (años desde el efecto de manipulación = 0.70 [0.28] y 0.51 [0.15], respectivamente). Además, encontramos más E. fuscus en donde el enfriamiento fue mayor (efecto de la diferencia en temperatura = −0.46 [ES 0.11]), y hubo algunas evidencias de que había mayor cantidad de P. subflavus en las secciones del hibernáculo que permanecieron cálidas después de la manipulación. Estos datos muestran que los murciélagos están respondiendo efectivamente al SNB mediante la selección de hábitat. En el caso de M. lucifugus, M. septentrionalis y posiblemente P. subflavus, esta respuesta es persistente, con los murciélagos agrupándose cada vez más en hibernáculos adecuados, mientras que E. fuscus permanece en sitios favorecidos previamente. Nuestros resultados sugieren que el enfriamiento de los sitios cálidos que reciben poco uso por parte de los murciélagos es una estrategia viable para combatir al SNB. Enfriamiento de los Hibernáculos de Murciélagos para Mitigar el Síndrome de Nariz Blanca.

Differential selection of roosts by Eastern Small-footed Myotis (Myotis leibii) relative to rock structure and microclimate.

Roost selection by insectivorous bats in temperate regions is presumably influenced by roost microclimates in relation to thermoregulatory strategies, but few studies have included temperature measurements in habitat selection models. Rocky landscape features are an important source of roosts that provide both shelter from predators and beneficial microclimates for bats. Most information about rock-roosting bats has been derived from western North America. We studied microhabitat selection by the Eastern Small-footed Myotis (Myotis leibii) on natural talus slopes and human-made stone structures in the Appalachian Mountains of Virginia and New Hampshire, relative to thermal and structural characteristics of rock crevices. Roosts were located with a combination of radiotelemetry and randomized visual surveys. Roost-switching behavior and structural characteristics of roosts did not appear to be influenced by the methods we used to locate roosts. Compared to random crevices, both sexes selected crevices with narrow openings, likely to provide protection from predators. Reproductive females also selected rocks that were larger and more thermally stable than random crevices, whereas males selected crevices that were structurally similar to random crevices but warmed more during the day. Rock size and other structural characteristics influenced temperatures of roosts and random crevices alike by inhibiting excessive daytime heating and nighttime cooling. Because large rocks were important for reproductive females, and talus slopes with large rocks could be limited, we recommend including rock size as a variable in landscape scale habitat assessments for Eastern Small-footed Myotis. Protecting or managing for habitat features with large rocks that receive high solar exposure could benefit Eastern Small-footed Myotis, and perhaps other rock-roosting species.

Helminth (Cestoda, Nematoda) and coccidian (Apicomplexa: Eimeriidae) parasites of the eastern small-footed myotis, Myotis leibii (Chiroptera: Vespertilionidae) from Arkansas, with a description of a new species of Eimeria.

During May and July 2016, 32 eastern small-footed myotis (Myotis leibii) were collected from five counties of northwestern Arkansas and their faeces examined for coccidian parasites. Four of 32 (13%) M. leibii harboured an eimerian that we describe here as new. Oocysts of Eimeria sassei sp. n. were ovoidal to ellipsoidal with a bi-layered wall and measured (length × width, L × W) 18.3 × 15.2 µm, with an L/W ratio of 1.2. A micropyle and oocyst residuum were absent but 1-2 polar granules were present. Sporocysts were ovoidal, 9.6 × 6.3 µm, with an L/W ratio of 1.5. A pronounced, button-like Stieda body was present but substieda and parastieda bodies were absent. A sporocyst residuum was present as distinct aligned or dispersed granules. One bat that we found dead was examined for helminth parasites. It harbored the tapeworm, Vampirolepis sp. and a nematode, Seuratum cancellatum. This is the first coccidian as well as the second helminths reported from M. leibii. In addition, this is the seventh species of coccidian parasite documented from Arkansas bats.