Too hot or too disturbed? Temperatures more than hikers affect circadian activity of females in northern chamois

Abstract

Though non–lethal, recreational activities often result in a spatial and/or temporal shift of activity in a large range of species because they are perceived as a risk. With the concurrent development of outdoors activities and the increase of temperatures due to climate change in mountainous ecosystems, mountain species face an increasing pressure in terms of managing their activity pattern to both limit risk exposure and reduce thermal stress. In this context, we investigated how female northern chamois adjust their summer circadian activity to spatio–temporal variations of both temperature and hikers disturbance. We found that chamois behaviour was more affected by high temperatures than by hikers disturbance. During the hottest days, they shifted their activity peak earlier in the morning (50 minutes earlier; and to a lesser extent, later in the evening), and were more active at night (+ 21.5% approx.) than during daytime (− 10.10% approx.). Their global daily activity was higher (+ 4.54% approx.) during the hottest than coldest days owing to a significant increase of activity level during the activity peaks. Conversely, hikers disturbance had almost no effect on activity peaks of chamois most likely due to a temporal mismatch with hikers arrival and departure. Spatial and temporal disturbance had also a weak effect on chamois activity level, except when considered together and during the hottest days (i.e. the most disturbed conditions) exacerbating the temporal report of activity at night those days. Low tolerance of chamois to hikers presence might have led to the pattern reported with a similar response whatever the intensity of encounter risk. These results might also suggest that behavioural changes buffering animals from high temperature (relocation into refuge areas) and/or from hikers presence (moving away temporarily from trails) allow them to marginally modify their activity pattern. In the context of ongoing socio–environmental changes, these findings stress the importance of conserving habitats providing both shelter against summer heat and human disturbance to mitigate their potential detrimental consequences.