Plant characteristics near the den entrance
Vegetation characteristics (richness, height, and biomass) have an
important influence on the den-selecting behavior of marmots (Li et al.
2017). We found that species richness in marmot activity areas was
significantly higher than that near the den entrance (Fig. 9). The
active area for these marmots was mainly concentrated within 2−100 m
near the den entrance. Plants in the active area provide food and water
for the marmots, as well as bedding for their nests in winter. Marmots
like to feed on succulent and highly nutritious forage and can get
enough water from their forage without additional water. Generally,
marmots like to excavate burrows on sloped terrain, but we found that
there were also some dens in flat areas (0.60/ha), and the species
richness in those areas was significantly higher than that on sloped
terrain. High species richness may be the reason why marmots are
attracted to these places to dig dens (Shi 2007).
Plant height also has a significant influence on the activities of
marmots (Li et al. 2017). We found that plant height within the activity
area was significantly higher than that near the den entrance (Fig. 9).
The low plants near the den entrance allow marmots to hide in their
tunnels while observing the outside environment (Shi 2007), thus
ensuring that there is no danger before they leave their dens. In
addition, marmots often stand and observe their surroundings when
feeding, and the exposed den entrance serves as a marker, which helps
them return to their den quickly when danger is detected (Zhang et al.
2019).
Because marmots are active only near the entrance to their dens, the
availability of food in those areas directly affects their den-selecting
behavior and quality of life. We found that the aboveground biomass in
the active area was significantly higher than that near the den entrance
(Fig. 9). Abundant food sources ensure that marmots can reserve enough
energy before hibernation to prepare for the 6-month hibernation period
(October to April).