Looking back at these Olympic marmot pictures I was struck by how they resemble our tortoiseshell cat, Trixie. In cats the mixed brown & black fur pattern can occur in females (or rarely in males with two XX chromosomes) where the primary color varies randomly from cell to cell, but in the marmots I think their coats are changing from light brown early in the season to dark brown near the end, and the marmots I saw on this occasion in the fall were in the process of transition.
Boolie 