“Lunar phobia” in bats has been widely discussed since its description in tropical bats in 1978. The phenomenon has been frequently contested and supported and was first reported in European bats in 2020. Our study seeks to clarify the debate by describing the relationship between the activity of selected swarming vespertilionid bats (Family: Vespertilionidae) and moonlight levels. To verify a potential connection to the latter, a swarming dataset was analysed in respect of estimated moonlight illumination. Moonlight estimates were based on geographical location and several lunar parameters, to accurately characterise the non-linear relationship between moon phase and illumination (lux). The swarming data consisted of 32 netting and 14 echolocation recording sessions collected between August and October 2014 and 2015. Our data included 3,265 netted bats from 13 species and 15,919 bat calls from 10 confirmed species. Data was collected at the large Central European hibernation/swarming site – Natura 2000 PLH080003 “Nietoperek” in western Poland (N 52.394400, E 15.480600). Generalised linear mixed models (GLMMs) determined insignificant relationships between bats and moonlight illumination. Our analysis confirms an absence of impact of moonlight intensity on swarming bats and thereby rejects the lunar phobia phenomena in at least six insectivorous bat species (Myotis myotis, M. daubentonii, M. nattereri, M. bechsteinii, Barbastella barbastellus, Plecotus auritus) swarming in the autumn.

We present the results of a study which describes the relationship between the western barbastelle Barbastella barbastellus a highly specialised moth predator, and its prey—moths of the genus Orthosia, another selective animal known to converge around a dominant producer of pollen and nectar in early spring—willow trees Salix sp. In order to describe this trophic relationship, we conducted acoustic recordings at five paired sites (willow/control tree) in proximity to known barbastelle hibernation sites (Natura 2000: PLH080003 and PLH200014) beginning in mid-March 2022 after the first willow blossom sighting. Our study confirms a relationship between willow trees and barbastelles during early spring, as their activity around them was significantly higher than control sites. We also explore the activity of barbastelles over time, finding that activity levels around willows significantly decrease from the night of the first recorded bat, while the abundance of non-moth specialist bats remains consistent. Short-time importance (directly after hibernation) of willows for a moth specialist bat is probably due to other species blossom, attracting alternative prey, and in consequence—the bat. This newly described relationship should influence current conservation measures aimed at barbastelles.

Key message: An outbreak of the European spruce bark beetle (Ips typographus L.) in spruce (Picea abies L.) dominated forest stands in the Białowieża Forest, Poland, has led to fundamental changes in forest characteristics. The species composition of regenerating stands now differs from earlier records findings, with oak, birch and rowan becoming dominant, while hornbeam numbers have decreased and Norway spruce is now sporadic, suggesting an ongoing period of reorganisation. Among the forest attributes showing the greatest degree of change are canopy architecture and sheltering opportunities—factors known to be most influential for volant-dependent wildlife. Context: The European spruce bark beetle (Ips typographus L.) targets Norway spruce (Picea abies (L.) H.). Once attacked, susceptible trees weaken and die. In planted forests with high proportions of Norway spruce, beetle outbreaks profoundly alter forest structure. The implications of such outbreaks on forest regeneration and their influence on dependent wildlife require ongoing research. Aims: We investigated how bark beetle-induced changes in Norway spruce stands alter forest structure characteristics and regeneration, and explored the potential consequences for forest-dependent volant vertebrates. Methods: We used a static comparative approach to assess differences in forest structure and regeneration between infested and non-infested Norway spruce stands in the Białowieża Forest, Poland. Eighteen forest variables were measured or derived, including indicators of canopy structure, tree composition, bark features, cavity presence, and microclimate. Sapling composition and regeneration frequency were also recorded to evaluate vegetation dynamics. Data were collected during 2022 and 2023. Results: Fifteen forest structural characteristics differed significantly post-infestation, including reduced tree density (trees per hectare), decreased vegetation clutter, and increased light transmittance. Daytime temperatures increased and humidity decreased, while nighttime conditions remained similar. The number of animal shelters in exfoliating bark increased, whereas tree crevices became less frequent. Sapling regeneration was higher in infested stands and dominated by oak (Quercus spp. L.), birch (Betula pendula Roth.), and rowan (Sorbus aucuparia L.). In contrast to earlier research, hornbeam was not the dominant sapling species, and Norway spruce saplings were infrequent. Conclusion: While our static comparative approach did not capture temporal dynamics or fully disentangle complex ecological interactions, it provided clear evidence that bark beetle outbreaks dramatically alter Norway spruce-dominated stands. The forest attributes most altered by infestation are well-established drivers of habitat suitability for forest-dwelling volant wildlife. We propose that cyclical beetle outbreaks in spruce-dominated forests act as drivers of accelerated natural succession, shifting species composition from planted Norway spruce to more naturally occurring species. Our findings highlight that bark beetle outbreaks represent natural change, not forest destruction, within this unique European forest ecosystem.

Our research focused on the roost preferences of two bat species in a forest environment. Throughout the Anthropocene, people have heavily altered the landscape. Forested habitation has declined, with remaining forests becoming fragmented and often deprived of old trees that provide shelter opportunities for bats. TReMs (tree-related microhabitats) are essential for forest-dwelling bat species as they provide an opportunity to roost and shelter. Following an infestation of Ips typographus L., the Białowieża Forest is saturated with dead spruce trees. We investigated roost selection in two forest-dwelling species, Barbastella barbastellus and Pipistrellus pygmaeus. To examine similarities or differences in roost selection between species, we radio-tracked 24 barbastelles and 13 soprano pipistrelles over three breeding seasons. We located a total of 48 barbastelle roosts and 15 pipistrelle roosts, together with the characteristics of the surroundings. We found that barbastelles select roosts almost exclusively in dead spruce trees (43/48), while pipistrelles selected roosts predominantly in live (n = 8) and dead (n = 5) broadleaved trees. Our results show that both bat species have clear differences in roost tree preference. In our study area, with an abundance of exfoliating bark, barbastelles showed a preference for roosting under flaking bark despite the availability of crevices within broadleaved trees. Our findings provide useful insight into forestry practices, highlighting the importance of standing dead trees.

The western barbastelle and soprano pipistrelle are prominent examples of European bats associated with forests. This makes them prone to adverse effects from human driven deforestation and forest structure alteration due to climate change. Although soprano pipistrelles have maintained stable population numbers, due to opportunistic ecology, the western barbastelle is considered one of the rarest bats in EU. In our study we investigated the spatial distribution and foraging habitat preferences of both species in the Białowieża Forest, a natural Central-European mixed lowland forest. To understand movement patterns during the summer seasons of 2022, 2023 and 2024 we radio tracked a total of 15 barbastelles (eight males and seven females) and 13 soprano pipistrelle females. Spatial information, in addition to standard home range and roost selection, was analysed for habitat preference using detailed forest structure maps obtained via Polish State Forests databases. Our study revealed that in well preserved forests bats home ranges were particularly small, including the smallest to date median home range for barbastelle females (224 ha). Additionally foraging habitat analyses (a Chi squared goodness of fit) revealed that soprano pipistrelles used all habitat types in line with availability while barbastelles showed a preference towards both wet and deciduous dominated habitats. Our research highlights the importance of effective water management in protected woodlands, as drying processes may have adverse consequences for the conservation of rare and protected species.