Hit the road bat! High bat activity on the road verges in Brazilian savanna

Roads have direct and indirect impacts on animals present in the surrounding habitats. Bats have extensive foraging ranges which may include roads, and are therefore particularly affected by them. This study aimed to analyze the effects of roads on bat activity and diversity in the Brazilian savanna. Nine transects were established in protected areas in central Brazil with sampling points at 0, 500, 1,000, and 1,500 m away from roads. At each point, we recorded bat echolocation for 12 h and evaluated the influence of road type and distance from the road on bat activity, diversity, and foraging effort. Season, normalized difference vegetation index (NDVI), and distance to water also were included in the models. We found that species richness in the dry season and activity of open space insectivores were significantly higher on road verges than on areas farther from roads, while foraging effort and activity of edge space insectivores were only influenced by season. The activity of edge space insectivores also increased significantly with increasing distance to water during the rainy season. We suggest that bat individuals do not forage near roads, but rather use them as flyways or cross them to forage in sites outside the protected areas, which can increase the risk of collision with vehicles.

Traffic noise playback reduces the activity and feeding behaviour of free-living bats

Increasing levels of road noise are creating new anthropogenic soundscapes that may affect wildlife globally. Bats, which form about a third of all mammal species, are sensitive bioindicators, and may be particularly vulnerable because of their dependency on echolocation. Here we present the first controlled field experiment with free-living bats. Using a Before-After-Control-Impact phantom road experimental design, we examine the impacts of traffic noise on their activity and feeding behaviour. Disentangling the impacts of traffic noise from other co-varying exposures such as habitat quality, the experiment demonstrates a significant negative effect on the activity of each of the five, ecologically different, species (genus for Myotis spp.) examined. This suggests that the results are widely applicable. The negative effects are largely attributable to noise in the sonic spectrum, which elicited aversive responses in all bat species tested,whereas responses to ultrasoundwere restricted to a single species. Our findings demonstrate that traffic noise can affect bat activity at least 20m away from the noise source. For Pipistrellus pipistrellus and Pipistrellus pygmaeus, feeding behaviour, as well as overall activity, was negatively affected. Ecological Impact Assessments are therfore needed wherever there are significant increases in traffic flow, and not just when new roads are built. Further research is required to identify effective mitigation strategies, to delineate the zone of influence of road noise, and to assess whether there is any habituation over time.

Variation in regional and landscape effects on occupancy of temperate bats in the southeastern U.S

Habitat loss, wind energy development, and the disease white-nose syndrome are major threats contributing to declines in bat populations in North America. In the southeastern US in particular, the recent arrival of white-nose syndrome and changes in landscape composition and configuration have driven shifts in bat species populations and distributions. Effective management strategies which address these large-scale, community-level threats require landscape-scale analyses. Our objective was to model the relationship between ecoregional and landscape factors and occupancy by all bat species in South Carolina, USA, during summer. We conducted acoustic surveys from mid-May through July 2015 and 2016 and evaluated temporally dynamic occupancy models for eight bat species or species groups at the 100 km2 level. We found significant effects of landscape factors such as ecoregion and forest edge density for three species, but habitat condition effects were not statistically significant for five other species. Thus, for some species, site-use analyses may be more appropriate than larger scale occupancy analyses. However, our occupancy predictions generally matched statewide historical distributions for all species, suggesting our approach could be useful for monitoring landscape-level trends in bat species. Thus, while our scale of study was likely too coarse for assessing fine-scale habitat associations for all bat species, our findings can improve future monitoring efforts, inform conservation priorities, and guide subsequent landscape-scale studies for bat species and community-level responses to global change.