Burrow distribution and density
We found 374 burrows: 241 within the high cluster, 127 within the low cluster and 6 on other locations around the valley (Fig. 1A). The burrow density in the whole searched area was 0.22 burrows/ha, on the high cluster 0.82 burrows/ha or 1.15 burrows/ha when the middle part of the third terrace was excluded. The density on the low cluster was 0.97 burrows/ha. The mean distance from a given burrow to another nearest burrow in the high cluster was 32.09 ± 35.63 m (range 1.9 – 382.06 m) and from five nearest burrows 61.28 ± 50.57 m (9.65 – 431.42). In the low cluster, those values are 37.01 ± 34.47 (1.9 – 188.98) from the nearest burrow and 69.15 ± 47.87 (13.48 – 243.83) from the five nearest burrows. Most marmot faeces were placed in stacks of several pellets on the mounds, only seldom in the surrounding area. We found no signs of plant succession on any burrow mound.