Trophic relationship between Salix flowers, Orthosia moths and the western barbastelle

Abstract 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

Barbastelle bats in a wind farm : are they at risk?

We need to know if and how western barbastelles Barbastella barbastellus are affected by wind farming in Sweden. This is because wind turbines are frequently constructed in barbastelle habitats and yet there is no national guideline on how the arising conflict should be handled. We studied the movement, behavior and mortality of a barbastelle population at a wind farm in southern Sweden, using radio-telemetry, automatic bat detectors and carcass searches. The tagged bats (6 males and 8 females) roosted mainly under loose bark of dead oak trees and foraged in patches of mature deciduous woodlands or pockets of mature spruce trees within 15 km of the roosts. Extensive areas of young spruce plantation, open farmland and lakes were not used for roosting or foraging but were crossed by commuting bats. Continuous recordings with bat detectors frequently picked up barbastelles at forest edges 30 m from the turbines, but rarely over the turbine pads within 10 m from the turbines and never at heights of 30 and 100 m at the turbine towers. Barbastelles were apparently not attracted to the wind turbines and did not seem to interact with them in any way. Carcass searches under 10 wind turbines at 1-week intervals over three summers did not reveal any dead barbastelles, although three other species were recovered. We conclude that wind farming is not nessarily incompatible with effective conservation of barbastelles in Sweden, but instead of focusing on wind turbines, effors should concentrate on (a) preservation and restoration of mature, age-structured deciduous woodlands and spruce forests, including very small and isolated patches, which provide food and roosts, and probably also (b) avoidance of outdoor lighting in areas used by barbastelles. Designating large circular buffer zones around each known or suspected colony according to current practice would be inefficient or meaningless in our case, because barbastelles use extensive home ranges and switch roost frequently. We argue that barbastelle management must be applied on a landscape scale

Barbastelle bats in a wind farm: are they at risk?

We need to know if and how western barbastelles Barbastella barbastellus are affected by wind farming in Sweden. This is because wind turbines are frequently constructed in barbastelle habitats and yet there is no national guideline on how the arising conflict should be handled. We studied the movement, behavior and mortality of a barbastelle population at a wind farm in southern Sweden, using radio-telemetry, automatic bat detectors and carcass searches. The tagged bats (6 males and 8 females) roosted mainly under loose bark of dead oak trees and foraged in patches of mature deciduous woodlands or pockets of mature spruce trees within 15 km of the roosts. Extensive areas of young spruce plantation, open farmland and lakes were not used for roosting or foraging but were crossed by commuting bats. Continuous recordings with bat detectors frequently picked up barbastelles at forest edges 30 m from the turbines, but rarely over the turbine pads within 10 m from the turbines and never at heights of 30 and 100 m at the turbine towers. Barbastelles were apparently not attracted to the wind turbines and did not seem to interact with them in any way. Carcass searches under 10 wind turbines at 1-week intervals over three summers did not reveal any dead barbastelles, although three other species were recovered. We conclude that wind farming is not nessarily incompatible with effective conservation of barbastelles in Sweden, but instead of focusing on wind turbines, effors should concentrate on (a) preservation and restoration of mature, age-structured deciduous woodlands and spruce forests, including very small and isolated patches, which provide food and roosts, and probably also (b) avoidance of outdoor lighting in areas used by barbastelles. Designating large circular buffer zones around each known or suspected colony according to current practice would be inefficient or meaningless in our case, because barbastelles use extensive home ranges and switch roost frequently. We argue that barbastelle management must be applied on a landscape scale.This project was funded by the Swedish Energy Agency through the Vindval program (no. 2016-000101). Capture and tagging of bats were carried out under licence from the Swedish Environmental Protection Agency (NV-08056-11) and the Ethical Committee in Malmö/Lund (M 65-16)

Absence of lunar phobia in European swarming vespertilionid bats

Abstract “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

Barbastelles in a Production Landscape : Where Do They Roost?

Extensive areas of old forests have declined all over the temperate regions of Europe mainly due to extensive forestry. This is likely to have negative impact on bats that roost in trees, such as the western barbastelle Barbastella barbastellus. We investigated its selection of summer roosts in a commercially used landscape in southern Sweden. We captured and radio-tracked 14 bats and found 17 occupied roosts. Nine of the roosts, including two used by a maternity colony (ca. 30 females), were located between overlapping boards on the gables of barns. The remaining eight roosts, all used by single individuals, were under lose bark on thin trees (DBH = 0.2-0.35 m). All recorded roosts had entrances pointing downwards, were adjacent to deciduous trees providing protective darkness, and were in areas without artificial lighting. In the barns, the bats avoided the northern aspect, which is the lightest (sun sets in the NW and rises in the NE). Roost temperatures did not differ between tree-and barn roosts. Average ambient light intensity on emergence and return was 13.3 lux (SD = 10.1 lux). Roosts in trees and barns shared common physical characteristics, yet despite this both maternity roosts were located in barns, perhaps because such roosts had more space than available tree roosts. Our results suggest that in areas deprived of large trees and extensive old forest, barbastelle shows flexibility in roost selection, although they consistently avoid artificial lights of all kinds. An abundance of potential roosts in trees and buildings and absence of light pollution are therefore key elements in a holistic conservation program for this species