Mammal watching is a far cry from that in much of the rest of the world. There are some nice species, but the diversity of mammals is low, and many of the more interesting animals are quite sparsely distributed and/or hard to see (it is difficult to find anywhere in the UK without perpetual disturbance from people). There aren't many places that are particularly good for seeing mammals generally: the Ardnarmuchan Peninsula is one of the best.