Nonlinear distribution pattern of hibernating bats in caves along an elevational gradient in mountain (Carpathians, Southern Poland)

Hibernacula of bats in Mexico, the southernmost records of hibernation in North America

Although Mexico holds the southernmost hibernating bats in North America, information on winter behavior and hibernacula microclimate use of temperate Mexican bats is limited. We studied hibernating bats at high altitudes (>1,000 m a.s.l.) in northern and central Mexico during 5 consecutive winters. Our aims were to document and describe the hibernacula, winter behavior (such as abundance and roost pattern), and microclimates (estimated as adjacent substrate temperature) of cave-hibernating bats in Mexico. We found 78 hibernacula and 6,089 torpid bats of 10 vespertilionid species, increasing by over 50% the number of cave-hibernating bat species and quadrupling the number of hibernacula for Mexico. Hibernacula were at altitudes between 1,049 and 3,633 m a.s.l., located in 3 mountain ranges, mainly in oak and conifer forests. Myotis velifer was the most common species, followed by Corynorhinus townsendii and C. mexicanus. We recorded the adjacent substrate temperatures from 9 species totaling 1,106 torpid bats and found differences in microclimate use among the 3 most common species. In general, abundance of torpid bats in our region of study was similar to those in the western United States, with aggregations of tens to a few hundred individuals per cave, and was lower than in the eastern United States where a cave may hold thousands of individuals. Knowledge of bat hibernation is crucial for developing conservation and management strategies on current conditions while accommodating environmental changes and other threats such as emerging diseases.

Distribution, Dominance Structure, Species Richness, and Diversity of Bats in Disturbed and Undisturbed Temperate Mountain Forests

The increase in mean annual temperature and reduction in summer rainfall from climate change seem to increase the frequency of natural and human-made disturbances to forest vegetation. This type of rapid vegetation change also significantly affects bat diversity. The aim of our study was to document differences in the ecological parameters of bat assemblages in different types of temperate mountain forests, particularly between disturbed and undisturbed coniferous and deciduous forests. Additionally, these issues were considered along an elevation gradient. We mist netted bats on 73 sites, between 931 and 1453 m elevation, in the forests of the Tatra Mountains in southern Poland. During 2016–2020, 745 bats, representing 15 species, were caught. The most abundant were Myotis mystacinus (Kuhl, 1817) (53.0%) and M. brandtii (Eversmann, 1845) (21.5%). We observed differences in species diversity, elevational distribution, and dominance between different types of forests and forest zones. Species richness peaked at around 1000–1100 m elevation. The highest species richness and other indices were observed in undisturbed beech stands, although they constituted only about 2.7% of the forest area. The lowest species diversity was observed in disturbed coniferous forests, in both the lower and upper forest zone. The species richness and dominance structure of bat assemblages were also found to depend on the location above sea level. In some bat species, the sex ratio was higher at higher elevations, and differences in the sex ratio in a few bat species, between different types of forests, were observed. Our findings suggest that disturbed, beetle-killed spruce forests are an unsuitable environment for some bat species.

The ecological niche and terrestrial environment jointly influence the altitudinal pattern of aquatic biodiversity

The altitudinal distribution of biodiversity in alpine ecosystems has captured academic attention, especially in streams because of their sensitivity to climate change. In the past years, research mainly focused on understanding the role played by alpine streams' internal factors such as aquatic environmental variables, as well as physical and hydrological conditions, on the shaping of benthic macroinvertebrate communities. More recently, external factors such as terrestrial environments were included in analyses worldwide. In particular, the inherent properties constituting the ecological niche of specific species were considered as factors regulating dispersal and influencing community construction. The objective of this study was to reveal the distribution pattern and the driving factors regulating aquatic biodiversity in alpine streams. We hypothesized that the altitudinal distribution of aquatic macroinvertebrates could be explained by the interaction of the aquatic environment with both species' ecological niche and the terrestrial environment surrounding their habitat, and that rare species display a more pronounced pattern than widespread dominant species. To test these hypotheses, samples were collected from two alpine streams situated on opposite slopes of Biluo Snow Mountain in Yunnan Province, China. Results of statistical analyses showed poor explanatory power from aquatic environmental factors, while the differences in vegetation type and the ecological niche of the species played an important role in determining the distribution pattern of aquatic biodiversity. Furthermore, we found that the altitudinal distribution pattern of aquatic biodiversity exhibits a bimodal type, with rare species fitting the bimodal peaks. These findings call for a better inclusion and further investigation on the effects of the terrestrial environment on aquatic ecosystems.

Home range size, habitat selection and roost use by the whiskered bat (Myotis mystacinus) in human-dominated montane landscapes

Our understanding of animal adaptations to human pressure is limited by the focus on rare taxa, despite that common species are more significant in shaping structure, function and service provision of ecosystems. Thus better understanding of their ecology and behavioural adjustments is central for drafting conservation actions. In this study, we used radio-telemetry on 21 individuals (10 females, 11 males) to provide data on spatial ecology, habitat selection and use of roosts of one of the commonest species, the whiskered bat (Myotis mystacinus), inhabiting the Carpathian Mountains (southern Poland). We tested, whether this species prefers natural over human-modified landscapes to seek prey and roosts. Mean home range size of the whiskered bat in the Carpathian Mountains was 26.3 ha (SE ± 3.2, Local Convex Hull) and 110 ha (SE ± 22.1, Minimum Convex Polygon with all locations), and included between one and three patches, among which bats moved along linear environmental features, such as scrubby banks of streams or lines of trees. During foraging whiskered bats selected small woodlands within agricultural landscapes, avoided large mountain forests and open areas, and used built-up areas proportionally to their availability. Whiskered bats occupied roosts located mainly in buildings (>97%), at an average altitude of 547.9 m above sea level (SE ± 8.3). Roosts were used for 5.4 days, on average. Our study shows that whiskered bats adapted well to the mosaic of semi-natural and anthropogenic habitats. It highlights the importance of buildings serving as roosts and small woodlands used as foraging areas in human-dominated montane landscapes.

Bird diversity along elevational gradients in the Dry Tropical Andes of northern Chile: The potential role of Aymara indigenous traditional agriculture

Understanding diversity patterns along environmental gradients lies at the heart of community ecology and conservation. Previous studies have found variation in bird diversity and density along “natural” elevational gradients in the Tropical Andes Hotspot. However, there is still a lack of knowledge about how bird communities respond to traditional land-use patterns, in association with other multiple drivers, along elevations. In the present study, we investigated biotic, abiotic and anthropogenic sources of variation associated with bird species diversity, density and turnover along a 3000-m elevational gradient, in southern limit of the Tropical Andes Hotspot, northern Chile. Over four seasons, we conducted 472 bird point count surveys and established 118 plots distributed across the Desert, Pre-Puna, Puna and High-Andean belts, where biotic, abiotic and anthropogenic factors were measured. We used mixed-effects models to estimate alpha diversity and multinomial Poisson mixture models to estimate species density, accounting for detectability. Species diversity and density increased until 3300 masl and then declined. This type of elevational pattern is characteristic of dry-based mountains, where environmental conditions are suitable at mid-elevations. Habitats shaped by traditional Aymara indigenous agriculture, associated with relatively high vegetation heterogeneity, hosted the highest values of bird diversity and density. Species turnover was structured by habitat type, while elevational ranges of most species were restricted to three relatively discrete assemblages that replaced each other along the gradient. Our study revealed a hump-shaped relationship between elevation and bird diversity and density in the Dry Tropical Andes Biodiversity Hotspot, supporting a diversity pattern characteristic of dry-based mountains of the world. Traditional Aymara agriculture may have constructed ecological niches for biodiversity at mid-elevations, enhancing vegetation heterogeneity, thus providing resources for resident and rare species. Increasing loss of traditional land-use may present a threat to the bird community in the Tropical Andes Hotspot.

Neutral colonisations drive high beta-diversity in cavernicole springtails (Collembola)

The theory of island biogeography predicts the effects of habitat isolation and size on species richness, community assembly, and the persistence of species. Various studies showed that habitat conditions and the ecology of species are also of relevance in explaining community assembly. Geographically isolated habitats like caves with rather constant environmental conditions provide models to test for the relevance of the above described variables. In this study we analysed springtails living in karst caves of the Romanian Carpathians and Dobrogea region. We considered phylogenetic relatedness, habitat and species characteristics to identify the relevant drivers of community assembly. Our data show that species richness of single caves is low. Neither phylogenetic relatedness nor habitat filtering and competitive interactions seem to shape species composition or to affect species richness. We found that glacial-interglacial cycles with subsequent range contractions and expansions might have led to independent and multiple colonisations of caves. Furthermore, single caves might have acted as refugia and thus might have provided the prerequisite for distinct evolution processes, leading to a high level of endemicity of these animal species.

Spatial and temporal distribution of bats (Chiroptera) in bright summer nights

Most bat species show plasticity in their choice of habitat and landscape. This study focuses on the distribution and activity of bats along the hillsides and onto the shores of a low salinity marine Norwegian fiord at 62°N. Ultrasound was recorded using D500 detectors in June and July at 42 different sites from the shoreline and up the hillsides to around 200 m. Detectors were placed in well-preserved woodlands. OnlyPipistrellussp., northern batsEptesicus nilssoniiand bats of theMyotisgenus were common. There was a clear non-linear spatial distribution pattern along these slopes, with a pronounced increase in the number of recorded bats at short distances from the shore. On all six nights, the detector closest to the shore had the highest number of recorded bats. A pattern was also seen in bat distribution over time.Pipistrellussp., northern bats andMyotisspecies all had a peak near the shore during the darkest part of the night, which is around 01.35 h in mid-summer at this latitude. At greater distances,Pipistrellussp. and northern bats had a peak around 40 minutes to one hour before the darkest part of the night, respectively. Here,Myotisspp. peaked about an hour after 01.35.