Yellow-bellied Marmot

I recently found a small colony of these animals in the Hat Creek Valley, just north of Mount Lassen, California.  I had never seen them at such a low elevation, just over 3,000 feet.  More used to seeing them at 8-10 thousand feet.  Their volcanic rockpiles were at the edge of a huge cow pasture.  I assume this is a young of the year, as I saw a litter of marmots of this same size next to a much larger adult.  D800e, Sigma 150-600 S @ 600, f 6.3, 1/800, ISO 800.  Comments and criticism are always appreciated.