Use of non-wildlife passages across a high speed railway by terrestrial vertebrates

1. Seventeen culverts and pathway passages across a high speed railway were monitored for one year in order to determine factors influencing their use by terrestrial vertebrates. 2. Carnivores, lagomorphs, small mammals and reptiles used the passages. Crossing rates generally reflected the spatiotemporal variation in vertebrate abundance and activity, suggesting that the passages could be valuable in allowing movement across the railway. 3. Wild ungulates known to be present did not use the passages, probably due to a combination of unsuitable dimensions and placement, a lack of cover near their entrances and human disturbance. Ungulates probably need specifically designed passages. 4. The presence of cover in the passage entrances favoured their use by carnivores, while small mammals preferred narrow passages where, presumably, predation risk was lower. Reptiles preferred passages of intermediate size, in which they moved between sun-warmed and shaded vertical surfaces for thermoregulation. 5. The main factor determining the use of passages by vertebrates was their location with respect to habitat. 6. Minor modifications to non-wildlife passages and to the management of surrounding areas may further improve the efficacy of these passages for allowing wildlife to cross linear barriers and, therefore, potentially reduce the effects of habitat fragmentation.