Abstract
Temperate bats exhibit seasonal and sex differences in resource selection and activity patterns that are influenced by ambient conditions. During fall, individuals face energetic trade-offs ...as they make choices relating to migration, mating, and hibernation that may diverge for populations throughout their range. However, research has largely focused on the summer maternity and winter hibernation seasons, whereas the prehibernation period remains comparatively understudied. Northern Myotis (Myotis septentrionalis) have experienced precipitous population declines from white-nose syndrome (WNS), leading to their protected status in the United States and Canada. Therefore, understanding their ecology throughout the year is paramount to inform conservation. We compared seasonal roosts and documented fall behaviors between study sites and sexes on 3 islands: Long Island (New York), Martha’s Vineyard, and Nantucket Island (Massachusetts). Between 2017 and 2020, we radio-tracked 54 individuals to analyze activity patterns and characterize fall roosts to compare with previously known summer roosts. Summer tree roosts were of smaller diameter, later stages of decay, and lower canopy closure than those used in fall. Both sexes selected trees of similar diameter and decay stage during fall. Anthropogenic roost use was documented in both seasons but use of anthropogenic structures was greater during fall and increased as the season progressed. Bats made short inter-roost movements with males traveling greater distances than females on average. Activity occurred until late November, with males exhibiting a longer active period than females. We tracked 23% of tagged bats to local hibernacula in subterranean anthropogenic structures, the majority of which were crawlspaces underneath houses. Use of anthropogenic structures for roosts and hibernacula may facilitate survival of this species in coastal regions despite the presence of WNS infections. Timing of restrictions on forest management activities for bat conservation may be mismatched based on prehibernation activity observed in these coastal populations, and the conservation of habitat surrounding anthropogenic roosts or hibernacula may be warranted if the structures themselves cannot be protected.
We explored seasonal roost differences and fall activity patterns of coastal Northern Myotis populations occurring on 3 islands in the northeast United States. In addition to tree roosts, bats used anthropogenic roosts during both summer and fall, and the mild coastal climate allowed for extended fall activity into late November with males remaining active for longer periods than females. Northern Myotis were tracked to local hibernacula in subterranean anthropogenic structures, which may allow individuals to maintain a greater proportion of acquired fat reserves for hibernation by eliminating the need to undertake energetically costly migrations to mainland sites. Given the precipitous population declines experienced by this species in areas where white-nose syndrome is established, these island habitats may serve as important refugia to facilitate species recovery efforts.
Owls prey on bats, but information on owl predation is scarce, its impact on bat mortality is unclear, and reports on behavioural responses, including roost-switching and fission–fusion behaviour, ...are equivocal. To study the link between owl predation and anti-predator behaviour in bats, we evaluated seven months of video recordings at roosts and the behaviour of 51 passive integrated transponder (PIT)-tagged bats and bats without tags in a geographically isolated colony of greater noctule bats (
Nyctalus lasiopterus
) in Spain. We found the tawny owl
Strix aluco
to almost continuously hunt
N. lasiopterus
, from perches and on the wing, well after the bats emerged at dusk and when they returned to their roosts. We recorded 39 unsuccessful and three successful attacks. Nonetheless, we found no evidence that owl predation modifies bat behaviour. While the bats constituted only a very small proportion of the owls' diet, owl predation accounted for an estimated 30–40% of bat mortality, which may have a significant impact on small, local or isolated bat populations, in particular, and thereby shape regional bat distributions. We hypothesize that low roost availability may also affect the bats’ potential response to predation, which could lead to natural predation having an excessive impact on bat populations.
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 austral 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 ambient 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.
in Spanish is available with online material.
Resumen
Existen pocos estudios sobre la ecología asociada a refugios diurnos de murciélagos en los bosques más australes de Sudamérica, donde las bajas temperaturas en verano y las prácticas de manejo del territorio suponen una barrera a la supervivencia de estas especies. El objetivo del presente estudio fue describir los hábitat y patrones de termorregulación asociados a refugios diurnos de dos especies de murciélagos presentes en Tierra del Fuego, Myotis chiloensis (murciélago oreja de ratón del sur) e Histiotus magellanicus (murciélago orejudo de Magallanes), durante la primavera tardía. Para lograrlo, instalamos radiotransmisores sensibles a la temperatura en 17 individuos, localizamos 17 refugios diurnos, y colectamos 81 días de datos de temperatura corporal de los individuos. Al mismo tiempo, registramos la temperatura ambiente para determinar su influencia en el uso de torpor. Ambas especies fueron encontradas en arboles de gran diámetro (77.8 ± 6 cm), normalmente vivos, de lenga (Nothofagus pumilio) ubicados en bordes de bosques maduros o al interior de bosques dominados por individuos más jóvenes y pequeños. Ambas especies de murciélagos utilizaron torpor frecuentemente, presentando temperaturas corporales bajo el umbral de torpor en el 89% de los días (n = 72) y un promedio de temperaturas corporales mínimas diarias de 16.5°C durante el curso de nuestro estudio. La temperatura ambiente promedio fue un predictor significativo del uso de torpor, con temperaturas corporales más bajas y períodos de torpor más largos en días más fríos. La temperatura corporal mínima y el período de torpor no varió entre las especies, tampoco variaron las características de los refugios diurnos. Nuestros datos muestran que la temperatura ambiente en primavera en Tierra del Fuego es una barrera energética que los murciélagos sortean utilizando torpor de manera frecuente y a través de la selección del hábitat. Recomendamos esfuerzos de conservación local que promuevan la preservación de árboles de gran tamaño, los cuales proveerían microclimas más cálidos para ambas especies de murciélagos.
The majority of the birds in different habitats are stressed due to alteration in multiple climate factors contributing to their loss. The present study has been planned to find the roosts ...composition of passerine birds in different major and sub-habitats of Punjab, Pakistan. In Faisalabad, of the four species, the higher number of exits was almost comparable, while Passer domesticus and Pastor roseus were more abundant than Tachycinet bicolor and Lanius cristatus. For the three remaining birds, total exits and returns were 180 for P. roseus, 181 for T. bicolor, and 179 for L. cristatus, respectively. Considering the exits in morning hours, a total of 314, 256, 246 and 210, were recorded from Sheikhupura. In Khanewal, of the four species, the highest exits and returns were that of P. domesticus (407; 451), followed by that of the P. roseus (273; 336), T. bicolor (242; 319) and L. cristatus (220; 397). The temperature imposed serious effects on roost exits for the four birds. The varied P-values which were higher (< 0.001***, < 0.001***, 0.002 **, <0.001***) appeared to limit the roost exits for them. Nonetheless, the impact of relative humidity exerted a strong influence on the T. bicolor (0.003**). In roosts return, it was seen that roost returns were even likely in warm temperatures and precipitation did not impose seriously on returns, and even in light rainfall. Nonetheless, relative humidity (RH) strongly impacted the sparrow. The T. bicolor and L. cristatus were adversely affected with the slopes (1.37) and (2.06), indicated with each percentage increase of relative humidity, and slope variations became least.
The microsites that animals occupy during the rest phase of their circadian activity cycle influence their physiology and behaviour, but relatively few studies have examined correlations between ...interspecific variation in thermal physiology and roost microclimate. Among bats, there is some evidence that species exposed to high roost temperatures (Troost) possess greater heat tolerance and evaporative cooling capacity, but the small number of species for which both thermal physiology and roost microclimate data exist mean that the generality of this pattern remains unclear.
Here, we test the hypothesis that bat heat tolerance and evaporative cooling capacity have co‐evolved with roost preferences. We predicted that species occupying roosts poorly buffered from high outside environmental temperature exhibit higher heat tolerance and evaporative cooling capacity compared to species inhabiting buffered roosts in which Troost remains well below outside conditions.
We used flow‐through respirometry to investigate thermoregulation at air temperatures (Ta) approaching and exceeding normothermic body temperature (Tb) among six species with broadly similar body mass but differing in roost microclimate (hot vs. cool roosts). We combined these data with empirical measurements of Troost for each study population.
Hot‐roosting species tolerated Ta ~4°C higher than cool‐roosting bats before the onset of loss of coordinated locomotion and non‐regulated hyperthermia. The evaporative scope (i.e. ratio of maximum evaporative water loss EWL to minimum thermoneutral EWL) of hot‐roosting species (16.1 ± 2.4) was substantially higher than that of cool‐roosting species (5.9 ± 2.4). Maximum evaporative cooling capacities (i.e. evaporative heat loss/metabolic heat production) of hot‐roosting species were >2, while the corresponding values for cool‐roosting species were ≤1.
The greater heat tolerance and higher evaporative cooling capacity of hot‐roosting species compared with those occupying cooler roosts reveal variation in bat evaporative cooling capacity correlated with roost microclimate, supporting the hypothesis that thermal physiology has co‐evolved with roost preference.
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
Anthropogenic land use changes, such as deforestation and commercial forestry, have substantially reduced natural roost sites for European bats. A common conservation solution is to provide ...artificial roosts (i.e. bat boxes), but there are concerns that these can become hotter than natural roosts in summer and could be death traps during heat waves. Nevertheless, females of several bat species form maternity colonies in these boxes, thus occupying hotter and more humid microclimates than solitarily roosting males. We tested if cooling efficiency and heat tolerance differ between sexes in European bats, and estimated the evaporative water requirements for bats living in bat boxes during hot summer days.
We used indirect calorimetry and thermometry to quantify thermoregulation at high air temperatures (Ta) in four species of verspitilionid bats that regularly occupy artificial roosts. We measured resting metabolic heat production, evaporative water loss rates (EWL) and body temperature (Tb) at Ta between 28°C and 48°C during summer. We predicted that females have higher evaporative cooling efficiency (evaporative heat loss/metabolic heat production) than males, allowing them to reach their heat tolerance limit at higher Ta.
We found no sex differences in maximum evaporative cooling efficiency, maximum Tb, and maximum Ta tolerated. However, the patterns of increasing EWL with Ta differed between sexes. Females tolerated higher Ta before increasing EWL than males and then rapidly increased EWL to higher values than males at the maximum Ta tolerated. These sex differences in heat dissipation strategies may reflect varying ecological and physiological constraints associated with different summer roosting habits.
Synthesis and applications. Our study revealed that some small European bat species are already at risk of succumbing to lethal dehydration during present‐day heat waves, with daytime evaporative water requirements equivalent to ~30% of body mass in sun‐exposed boxes. For conservation managers working with common European bat species, particularly those in monoculture forests with woodcrete bat‐boxes, our physiologically informed recommendations include positioning boxes in diverse locations varying in aspect and sun exposure. This will ensure thermal heterogeneity of roost sites and provide a wide gradient of microclimate conditions, allowing for roost switching when necessary.
Our study revealed that some small European bat species are already at risk of succumbing to lethal dehydration during present‐day heat waves, with daytime evaporative water requirements equivalent to ~30% of body mass in sun‐exposed boxes. For conservation managers working with common European bat species, particularly those in monoculture forests with woodcrete bat‐boxes, our physiologically informed recommendations include positioning boxes in diverse locations varying in aspect and sun exposure. This will ensure thermal heterogeneity of roost sites and provide a wide gradient of microclimate conditions, allowing for roost switching when necessary.
•Bark bettle outbreaks resulted in a lot of standing dead spruce trees.•Barbastelle activity significantly increased in areas of bark beetle outbreaks.•The bats' activity increases 1–2 years after ...the appearance of the bark beetle.•A possible reason is appearance of new roosting places and the colonization of the area by bats.•Salvage logging and dead spruce cutting can be detrimental to the barbastelle population in Białowieża Primeval Forest.
Natural forest disturbances are increasingly common due to ongoing climate changes but their impact on most of forest organisms is poorly studied. Here we investigate the link between spruce bark beetle Ips typographus outbreak in 2011–2017 in Białowieża Primeval Forest (Poland) and activity of a forest bat of conservation concern: the western barbastelle Barbastella barbastellus. Bats were surveyed by recording ultrasound signals on 8 transects (3 km each) in a mixed coniferous and deciduous forest with a different share of Norway spruce. The activity pattern of bats was found to correlate with the number of bark beetle infested Norway spruces in the following years within a 1 km buffers of the transects (339,354 trees in total) using generalised additive mixed models. We demonstrated that the number of bark beetle infested spruces was a positive predictor of barbastelle activity largely with 1- and 2-year lags: number of spruces infested in a year correlates with bat activity one and two years later. This latency period most likely mirrors the decomposition process in standing dead spruces. We suspect that the massive appearance of dying Norway spruces provides the barbastelle with roosting sites under the bark and may lead barbastelle to colonize spruce stands otherwise rarely occupied by this species. It cannot be excluded, however, that other mechanisms (e.g. increased food biomass or availability) also drive the barbastelle to colonize stands infested by bark beetle. Our findings suggest that salvage logging and dead spruce removal, routinely implemented in stands infested by bark beetle, including Białowieża Primeval Forest, may negatively impact western barbastelle population.
Collective behaviour is typically thought to arise from individuals following fixed interaction rules. The possibility that interaction rules may change under different circumstances has thus only ...rarely been investigated. Here we show that local interactions in flocks of wild jackdaws (Corvus monedula) vary drastically in different contexts, leading to distinct group-level properties. Jackdaws interact with a fixed number of neighbours (topological interactions) when traveling to roosts, but coordinate with neighbours based on spatial distance (metric interactions) during collective anti-predator mobbing events. Consequently, mobbing flocks exhibit a dramatic transition from disordered aggregations to ordered motion as group density increases, unlike transit flocks where order is independent of density. The relationship between group density and group order during this transition agrees well with a generic self-propelled particle model. Our results demonstrate plasticity in local interaction rules and have implications for both natural and artificial collective systems.
Bats are a reservoir for many viruses causing haemorrhagic fevers. Proximity to bats is a risk factor for virus spillover to animals and humans. We conducted this study to assess knowledge, ...perceptions, and exposure to bats in communities living near bat roosts in Bundibugyo District, Uganda.
A cross-sectional study using mixed methods with both quantitative and qualitative data was conducted between September and December 2022. Participants for the quantitative data (survey) (n = 384) resided near bat caves and/or roost sites and were selected using multistage random sampling. The survey investigated participants' prior exposure to bats, as well as knowledge and perceptions of bat exposure. Logistic regression was used to determine factors associated with bat exposure. Participants for the qualitative data (focus group discussions) (n = 10, 6-8 participants each) were purposely selected based on engagement in guano mining, hunting, and farming activities. Perceived risk associated with bat-related activities were identified and ranked in the focus group discussions using participatory epidemiology tools.
In total, (214/384, 55.7%) had a history of bat exposure and (208/384, 54.2%) had poor knowledge of risk factors associated with bat exposure. Increased exposure to bats was associated with being male (OR = 1.6; 95% CI: 1.0, 2.4 p-value = 0.038), staying in urban areas (OR = 1.9; p-value = 0.010), hunting (OR = 10.9; p-value = 0.024), and positive perception to bat guano being safe as fertiliser (OR = 2.5; p-value = 0.045). During the proportional piling process, a total of 7 risk factors were identified by 10 groups with hunting during an outbreak and consumption of bats being the most frequently identified. Overall, there was a strong statistical agreement in the ranking across the 10 focus groups (W = 0.52; p < 0.01; n = 10). Based on the provided data, the adjusted odds ratio of 0.7 for the good measures (p-value = 0.112), suggests a potential protective effect on the risk of bat exposure.
Communities living around bat roosts frequently come into contact with bats, yet there is inadequate awareness regarding the behaviors that can lead to the transmission of bat- borne diseases to humans. It is essential to undertake educational initiatives and preventive measures to minimise the risks of bat-related infections. The need for targeted health communication and education efforts to address these knowledge gaps and promote an accurate understanding of bats and disease transmission. Understanding of diseases associated with bats will minimize bat-related health risks especially in communities engaged in wildlife hunting.
Cranioleuca pyrrhophia (Vieillot, 1817) is a furnarid bird that is distributed in Brazil, Paraguay, Uruguay and Argentina. The nests are globular or vertical ovoid, with an upper lateral entrance, ...built of sticks, and the brood chamber lined with soft plant materials and feathers. In addition, it builds roots with soft plant materials in the form of a tunnel with an entrance on each side. The insects found in one nest of C. pyrrhophia in Zelaya (Buenos Aires), two nests in Santa Rosa and Toay (La Pampa) and 8 roots in Toay (La Pampa) were adults belonging to Coleoptera, Diptera, Hemiptera, Hymenoptera y Lepidoptera. Only 2 Coleoptera families and 2 Hemiptera families are shared among the nests and roots in the province of La Pampa. The 3 families of Coleoptera present
in the Buenos Aires nest are shared with the roots of La Pampa and only 1 family (Curculionidae) with nests of La Pampa. The order Hymenoptera was only present in the Buenos Aires nest. The Coleoptera and Hemiptera species used the nests to hibernate, with two species showing the highest abundance, Cycloneda ancoralis and Missipus variabilis. The low abundance of insects in the roosts is related to the material witj which they are built. The roosts of this species are redescribed
Cranioleuca pyrrhophia (Vieillot, 1817) es un furnárido que se distribuye en Brasil, Paraguay, Uruguay y Argentina. Los nidos son globulares u ovoides verticales, con una entrada lateral superior, construidos de palitos, y la cámara de cría revestida de materiales vegetales blandos y plumas. Además construye dormideros con materiales vegetales blandos en forma de túnel con una entrada a cada lado. Los insectos hallados en un nido de C. pyrrhophia en Zelaya (Buenos Aires), dos nidos de Santa Rosa y Toay (La Pampa) y 8 dormideros de Toay (La Pampa) fueron adultos pertenecientes a Coleoptera, Diptera, Hemiptera, Hymenoptera y Lepidoptera. Solo 2 familias de Coleoptera y 2 familias de Hemiptera son compartidas entre los nidos y los dormideros de la
provincia de La Pampa. Las 3 familias de Coleoptera presentes en el nido de Buenos Aires son compartidas con los dormideros de La Pampa y solo 1 familia (Curculionidae) con nidos de La Pampa. El orden Hymenoptera solo estuvo presente en el nido de Buenos Aires. Las especies de Coleoptera y Hemiptera utilizaron los nidos para hibernar, y fueron dos especies las que presentaron mayor abundancia, Cycloneda ancoralis y Missipus variabilis. La baja abundancia de insectos en los dormideros está relacionada con el material con que estos son construidos. Se redescriben los dormideros de esta especie
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