Behavioral state-dependent selection of roads by guanacos

Context

Widespread globally, roads impact the distribution of wildlife by influencing habitat use and avoidance patterns near roadways and disrupting movement across them. Wildlife responses to roads are known to vary across species; however within species, the response to roads may depend on the season or the individual’s behavioral state.

Objectives

We assess the movement behavior and space use of the most widespread large herbivore in Patagonia, the guanaco (Lama guanicoe). We estimated the preference or avoidance to paved or unpaved roads (the proximity effect) and the preference or avoidance to traverse them (the crossing effect).

Methods

Using GPS collar data, we combined Hidden Markov Models with an integrated step selection analysis to segment guanaco movement trajectories into individual behaviors and test for differences in road effects on movement.

Results

We found that guanacos display distinct movement responses to different types of roads depending on their behavioral state. Guanacos select for proximity to paved roads while foraging, but against them when traveling. Yet, guanacos select for unpaved roads when traveling. Despite the selection for proximity to paved roads, guanacos avoid crossing them, irrespective of their behavioral state.

Conclusion

Our findings offer significant implications for guanaco distribution and management across Patagonia. The selection for roads strongly influences the distribution of guanacos, which could concentrate grazing in some areas while freeing others. Despite potential benefits such as increased vegetation near roadsides, increased association with roads while foraging may result in an ecological trap. Finally, the strong aversion to crossing paved roads raises concerns about habitat loss and connectivity.