Bats are long-lived mammals with low reproductive rates, making them susceptible to developments that reduce reproductive output or increase mortality. Roads destroy. degrade and fragment habitats, reducing the ability of bats to roost, feed and reproduce. Current mitigation techniques have not been proven to be effective at conserving bats at the population level.34.1 Road effects vary among species depending on flight style and habitat use, but many species are affected.34.2 Roads can act as barriers to the movement of bats, and many species suffer traffic mortality attempting to cross roads.34.3 Artificial light deters some bat species while attracting others, and a policy of no lighting' is recommended for bats.34.4 Traffic noise may reduce the flight activity and foraging efficiency of bats.34.5 Protection of roosts and foraging sites during and after roadworks is critical to bat survival.34.6 Underpasses can effectively reduce the barrier effect and reduce the number of roadkills for some bat species.34.7 Other attempts to reduce the barrier and mortality effects for bats are unproven, and further research is required before widespread implementation.It is important to conduct thorough pre-construction bat surveys and bring objectivity and rigour into the design and testing of mitigation features.

In many social animals, group members exchange information about where to feed. Thereby, they may gain direct benefits, for example, if social hunting enhances individual foraging success. Alternatively, individuals may receive indirect fitness benefits by preferentially sharing information about suitable feeding sites with kin. Indeed, in some species, a positive correlation between the degree of relatedness among individuals and the overlap among their foraging areas was found. However, sharing foraging sites with kin can also have costs if it increases food competition, which is not compensated by direct benefits. The goal of this study was to investigate whether sharing of individual foraging areas in female Bechstein's bats is best explained by kin selection or by direct benefits through social foraging. To assess their individual foraging behaviour, we analysed radio-tracking data of 22 members of one maternity colony, including nine mother-daughter pairs, seven pairs of less closely related individuals and six pairs of unrelated bats. We examined the bats' fidelity to specific foraging areas during several years and quantified the influence of kinship on the overlap among individual foraging areas. By measuring how close to each other the bats foraged, we assessed whether individuals with overlapping areas are likely to forage together. Our study confirms previous findings that Bechstein's bats show high fidelity to foraging areas across years. Moreover, we found that relatives share foraging areas significantly more often compared with unrelated colony members. Finally, our data reveal for the first time that most colony members that share foraging areas are unlikely to forage together. This suggests that female Bechstein's bats gain no direct benefits from sharing foraging areas with members of the same maternal lineage. Our findings also have implications for conservation as habitat loss within a colony's home range might expose entire matrilines to high risks.

Most social animals depend on group decisions for coordination. Recent models suggest that the level of interindividual conflict strongly influences whether groups reach a consensus during decision making. However, few experimental studies have explored how wild animals make group decisions in situations with conflicting interests. Such experimental data are particularly lacking for animal societies with regular fission and fusion of subgroups. In this long-term study, we varied the level of conflict of interest among members of three wild Bechstein's bat (Myotis bechsteinii) colonies with high fission-fusion dynamics experimentally to explore whether the bats adapt their group decisions about communal roosts accordingly. In situations with low levels of conflict of interest, a minority of bats experiencing a roost as suitable was sufficient for a group consensus to use it communally. In contrast, if their interests diverged strongly, the bats no longer sought a compromise, but based their roosting decisions on individual preferences instead. Our results demonstrate that the rules applied to make group decisions can vary with the level of conflict among the individual interests of group members. Our findings are in agreement with predictions of the models and provide evidence for highly flexible group decisions within species.

It is generally recognized that roads can adversely affect local animal populations but little is known how roads affect bats. In particular, no study compared the response of bats that differ in foraging ecology to motorways that cut through the breeding habitat. As bats are key species in conservation, such data are urgently needed for designing management plans. Using radio-telemetry, mist netting, and mark-recapture data we investigated the effects of a motorway with heavy traffic on the habitat use of two threatened forest-living bats. We compared barbastelle bats (Barbastella barbastellus), which forage in open space, to Bechstein’s bats (Myotis bechsteinii), which glean prey from the vegetation. Five of six radio-tracked barbastelle bats crossed the motorway during foraging and roost switching, flying through underpasses and directly over the motorway. In contrast, only three of 34 radio-tracked Bechstein’s bats crossed the motorway during foraging, all three using an underpass. Bechstein’s bats, unlike barbastelle bats, never crossed the motorway during roost switching. Moreover, only in Bechstein’s bats individuals foraging close to the motorway had smaller foraging areas than individuals foraging further away, whereas other forest edges had no such effect. Our data show that motorways can restrict habitat accessibility for bats but the effect seems to depend on the species’ foraging ecology and wing morphology. We suggest that motorways have stronger barrier effects on bats that forage close to surfaces than on bats that forage in open space, and discuss the implications of our findings for bat conservation during road construction.