How do humans impact yellow-bellied marmots? An integrative analysis

Abstract

While many studies document specific human impacts on the behaviour and physiological responses of wildlife to humans, most have focused on these responses independently and over relatively short periods of time. To address this, we studied a suite of responses in yellow-bellied marmots (Marmota flaviventer) in two distinct years, 9 years apart. We first quantified the rate that vehicles, pedestrians, and bicycles passed marmot colonies, focusing on two years (2009 and 2018) to determine how, if any of these relationships changed over time. We then asked whether these disturbances were associated with marmot physiological responses including neutrophil-lymphocyte ratios (NLR), and faecal glucocorticoid metabolites levels (FGM), as well as behavioural responses including flight initiation distance (FID) and the time marmots allocated to foraging, and finally a key fitness correlate—the rate of mass gain. We found that the number of vehicles and pedestrians passing within 300 m of a marmot colony stayed relatively constant between years, while there was variation in bicycles passing by marmot colonies. Despite similar length in growing seasons, marmots at colonies that had higher disturbance gained mass more rapidly in 2018 than in 2009. By examining a suite of physiological, behavioural, and key fitness correlates, and how they changed, our findings are consistent with the hypothesis that marmots became more tolerant of human disturbances over time. This provides promise for this population in dealing with inevitable increases in eco- and nature-based tourism.