Fecal Pellet Counts as a Technique for Monitoring an Alpine-Dwelling Social Rodent, the Hoary Marmot (Marmota caligata) [Comptages des crottes comme technique pour suivre un rongeur social alpin, la marmotte givrée (Marmota caligata)].

Résumé

We evaluated fecal pellet counts as an index of hoary marmot (Marmota caligata) social group size in order to develop a simple, inexpensive method for monitoring population change of a widely distributed, but poorly studied alpine mammal. Fecal pellet counts were conducted in three separate seasons along several 2 m x 100 m transects located parallel to and 10, 20, and 30 m from the edge of alpine boulderfields (talus) occupied by marmots. Marmot activity and location relative to talus was also determined to assess the proportion of time spent foraging as a function of distance from refuge. Marmots spent 74% of their activities in meadows at a mean distance of 11.6 m from talus, and activity in meadows declined with increasing distance from talus, as did fecal pellet counts. Fecal counts at 10 m from the edge of talus were strongly and linearly related (r2 = 0.89) to marmot abundance. The functional equation of marmot abundance predicted marmot abundance in five independent social groups within 17% of the observed group size. Fecal pellet counts appear to provide a precise index of marmot group size suitable for long-term monitoring of population change.