Roosting ecology of the southernmost bats, Myotis chiloensis and Histiotus magellanicus, in southern Tierra del Fuego, Chile

Abstract

There are few studies of day-roosting ecology of bats inhabiting the southernmost forests of South America, where cool summer temperatures and land management practices pose several challenges. The goal of the present study was to describe day-roosting habitats and patterns of thermoregulation in two bat species occurring on Tierra del Fuego, Myotis chiloensis (Chilean myotis) and Histiotus magellanicus (southern big-eared brown bat), during late spring. To do so, we tagged 17 bats with temperature-sensitive radio-transmitters, located 17 day-roosts, and collected 81 days of skin temperature data. We concurrently recorded ambient air temperature to determine its effect on torpor use. Both species were found roosting in large diameter (77.8 ± 6 cm), typically live, Nothofagus pumilio trees (lenga) located on the edges of forest gaps or within stands primarily composed of smaller, younger trees. Bats of both species frequently used torpor, with skin temperatures dropping below a torpor threshold on 89% of days (n = 72) and daily minimum skin temperatures averaging 16.5 °C over the course of our study. Average daily air temperature was a significant predictor of torpor use, with lower skin temperatures and more time spent in torpor observed on colder days. Minimum skin temperature and time spent torpid did not vary between bat species, nor did the characteristics of day-roosts. These data show that spring temperatures in Tierra del Fuego pose an energetic challenge that bats meet through frequent use of torpor, and likely, habitat selection. We recommend local conservation efforts keep these thermal challenges in mind by retaining large trees, which may provide warmer microclimates or room for social groups.

Winter activity of boreal bats

“…Recently, the use of acoustic monitoring and studies utilizing temperature sensing radio tags has brought new insight to the hibernation behaviour of more elusive species (e.g. Lausen and Barclay 2006;Lemen et al 2017;Ossa et al 2020), to which our results add. However, climate change may affect the usability of these sites for bats, as the loss of snow cover is likely to have a great impact on the microclimates of these hibernacula.…”

Winter activity of boreal bats

“…Most research on hibernation behavior thus far has been conducted on species that hibernate in caves in karst regions, often in large numbers, leaving the majority of species not encountered in these environments understudied. Recently, the use of acoustic monitoring and studies utilizing temperature sensing radio tags has brought new insight to the hibernation behavior of more elusive species (e.g., Lausen and Barclay 2006;Lemen et al 2017;Ossa et al 2020), to which our results add. However, climate change may affect the usability of these sites for bats, as the loss of snow cover is likely to have a great impact on the microclimates of these hibernacula.…”

Efecto de la configuración de áreas forestales sobre la comunidad de murciélagos insectívoros en paisajes agroforestales

“…La densidad de árboles aislados tuvo un impacto significativo y negativo en la actividad de dos especies de murciélagos de espacios abiertos ( T. brasiliensis y Lasiurus spp.) en el paisaje B. Este es un resultado interesante porque normalmente estos árboles aislados podrían ser utilizados por los murciélagos como refugios (Altamirano et al, 2017) o como puntos de referencia (Harms et al, 2020; Morris et al, 2010; Muñoz et al, 2019; Neece et al, 2018; Ossa et al, 2020). Este resultado evidencia que las dos especies de murciélagos de espacios abiertos evitaron sitios con alta densidad de árboles aislados y por lo tanto, percibieron estos paisajes como áreas no aptas.…”

“…En Chile, a pesar de su importancia ecológica y económica (Rodríguez‐San et al, 2020), se desconocen muchos aspectos de su ecología y distribución a lo largo del país, lo que dificulta los esfuerzos de conservación, aun cuando están legalmente reconocidos como animales benéficos para la agricultura. La mayoría de las especies de murciélagos tienen fuertes hábitos forestales y requieren de la conservación de estos elementos del paisaje para su supervivencia, ya que estas áreas les proporcionan refugios, zonas de reproducción y alimentación (Altamirano et al, 2017; Ossa et al, 2020). Aunque la zona centro‐sur de Chile ha sido reconocida como un punto caliente global de biodiversidad (Fuentes‐Castillo et al, 2020; Myers et al, 2000), en las últimas décadas el valle central ha sufrido importantes transformaciones antrópicas con gran pérdida de bosque nativo, que se han transformado en pastizales para ganado, cultivos y plantaciones forestales de especies exóticas como Pinus spp.…”