Direct and indirect effects of roads on activity patterns of the largest South American artiodactyl (Lama guanicoe) in a hyper-arid landscape

Abstract

The effects of roads on natural environments have been studied in many places around the world. The presence of roads can be considered for native animals as a disturbance stimulus. Besides, roads can facilitate arrival and entry of alien species, such as domestic and feral ungulates, which sometimes compete with native species. Due to this, we assessed if the presence of roads affect directly or indirectly, through the presence of non-native ungulates, the activity patterns of the guanaco, a native ungulate. Sampling was conducted during three years, in two types of roads. We used camera traps at different distances from these infrastructures. We found that the abundance of guanacos was not affected by that of non-native ungulates, but it was higher in the dry than in the wet season. In relation to activity patterns, the guanaco showed a diurnal activity pattern with an activity peak at 12:00 h. Moreover, donkeys showed cathemeral activity pattern, whereas cattle had the same activity pattern as guanacos, causing a switch to bimodal activity pattern of guanacos in the presence of cattle. We proved an indirect effect of roads, a temporal segregation of guanacos probably caused by cattle. Our results demonstrate that the activity pattern of guanacos changes from unimodal to bimodal near the paved road, probably due to the high abundance of cattle near these areas. Our findings also highlight the need for further studies to discriminate between direct and indirect effects of roads on wildlife in South American deserts.