High-speed railways are not barriers to Pyronia tithonus butterfly movements

Linear infrastructures such as railways and roads can be barriers to the movements of individuals and, hence, may have strong impacts on populations. We tested the barrier effect of a high-speed railway for Pyronia tithonus, a butterfly species showing homing behaviour when displaced. We captured, marked and displaced 152 individuals in two different locations. One-third of the butterflies were released at a capture plot, one-third on the other side of the railway (in a similar habitat) and one-third on the same side but 100 m away from the capture plot. We obtained recapture rates of 40 and 23 % per location. Many (31 %) butterflies crossed the railway, showing homing behaviour. Thus, contrary to wide, busy roads, high-speed railways do not seem to be barriers for these butterflies. We suggest that in an intensive agrarian landscape, railway verges can play a substitution habitat role for grassland butterflies.