Preliminary field inspection and searching for burrows.
During the field inspection, we searched the valley for marmot burrows and recorded their location using a GPS device. We treated every entrance as a separate burrow unless several entrance corridors were clearly merging into one corridor. We noted the presence or absence of plants on the mound. A common method to check the activity status of a burrow is checking for the presence of fresh faeces (Karels et al., 2004). We suspected, that due to the type of environment fresh faeces dry out very quickly, but then remain intact for a long time. Therefore, we counted all burrows which had any faeces on them. Burrows without faeces were abandoned and usually damaged and we did not record them. The area we searched was 17.18 km2 (Fig. 1A).