...small 'rabbit mice' - mice with big ears...
Probably
pikas.
Marmots are very opportunistic.
Several years ago while sitting down at Trail Camp after a summit, I saw a camper lay down her bag of gorp behind her.
As soon as she sat that down, a marmot came up behind her and took off with her bag of gorp.
She got her bag back with no harm to the gorp.