Effects of roads on the behaviour of the largest South American artiodactyl (Lama guanicoe) in an Argentine reserve

Abstract

Animals may divert time and energy in similar ways in the presence of predators, humans or landscape infrastructures. Roads have facilitated the economic and social development of human populations. Nevertheless their presence and human use cause environmental changes, such as clearing, which increase perception of predation risk. Among the responses to this are changes in animal behaviours. In the present study, we sought to assess whether roads in an Argentine reserve affect perception of predation risk by guanacos, Lama guanicoe, through behaviour changes. We analysed the effects of two types of roads (unpaved track and paved route) and their surrounding environment (e.g. vegetation structure) on group size variation and on three behaviours: vigilance, foraging and movement. We also used the group structure of guanacos, such as the number of calves, to explain these behaviours. Roads in the protected area had no impact on the size of guanaco groups. However, individuals in larger groups were less vigilant and foraged more closely to roads, indicating that closeness to roads is less risky for these animals. Although guanacos' time spent moving was not affected by roads, nearness to the unpaved track and high plant cover showed the highest proportions of animals moving in the area, and individuals moved more when in small groups and in areas with medium-height vegetation. The number of individuals displaying vigilance or foraging behaviours was not affected by any of the explanatory variables. Based on these findings, we conclude that guanacos perceive the roadside environment as safer, possibly because open areas adjacent to roads facilitate detection of predators. Knowing the effects of roads on wildlife in protected areas is necessary to find ways to reach a balance between the economic development of a region and conservation of its biodiversity.