Forest roads as partial barriers to terrestrial salamander movement

Roads can fragment animal populations by disrupting movement among formerly continuous habitats. Although models have demonstrated that disrupted movement can contribute to long-term extinction, there are few empirical data on the effects of roads on animal movement. We used displacement and homing experiments to determine whether forest roads are barriers to the movement of terrestrial salamanders. We displaced 1471 red-backed salamanders (Plethodon cinereus) across five forest roads and compared return rates to those of salamanders displaced equal distances toward the forest interior Roads significantly reduced the return rate, of salamanders, with a mean reduction of 51%. Steep roadside verges further reduced return rates, particularly for salamanders moving downhill across verges. The permeability of roads to salamander movement did not appear to be related to road surface type. Gravel roads bad both the highest and lowest observed permeability with the two paved roads intermediate between these. Me conclude that narrow forest roads are partial barriers to salamander movement and that steep roadside verges may exacerbate these effects.