UCLA

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, and few have examined fitness correlates of the response to humans. To address this limitation, we studied yellow-bellied marmots (Marmota flaviventer). We first quantified the rate that vehicles, pedestrians and bicycles passed marmot colonies. We then asked whether variation in these disturbances were associated with marmot physiological responses including neutrophil-lymphocyte ratios (NLR), and faecal glucocorticoid metabolites levels (FGM), behavioural responses including flight initiation distance (FID) and the time marmots allocated to foraging, and a key fitness correlate—the rate of mass gain. We focused on two years (2009 and 2018) when we quantified human disturbance in detail to determine if and how the relationships changed over time. 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 between 2009 and 2018. Despite similar length growing seasons, marmots at colonies that had more disturbances gained mass more rapidly in 2018 than in 2009. By examining a suite of physiological, behavioural and key fitness correlates, and how they changed over time our findings are consistent with the hypothesis that marmots became more tolerant of human disturbances. This provides promise for this population in dealing with inevitable increases in eco- and nature-based tourism.