Brown Marmot

I too have found many as secondarys in Blade Edge Mountains. I've only been lucky enough to catch an uncommon so far. UPDATE! Got a rare hunting the same place the other guy mentioned above Gruul's Lair.

There are tons of these guys near Seredane in Hinterlands!

A silvermane stalker (wolf) has just killed the rare I was about to battle !!!! Grrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr ...

Found several today, two greens and a rare,  came as a second pet to the Basilik.  So keep hunting on the land just above and behind Gruul's Lair.

Found one of these guys tagging along with a rock viper third battle in the Bloodmaul Ravine of Blade's Edge.  At that point after reading the last comment I'd given up, so it was a pleasant surprise!

Edit: Im finding them tagging along all over.  Ive caught two already, one of which was a rare.  Just be patient, they seem to tag along with every type of pet in the zone.  The rare was with a Scalded Basilisk Hatchling, if you were curious.

My search for the apparently elusive Brown Marmot in Blade's Edge has been abandoned. Despite traversing the entirety of the zone, as well as engaging in numberous Pet Battles to see if one would tag along as a friend to a different pet, I have been extremely unsuccessful in locating a single one of these rodents.