The squirrels are quite small but very cute!
When you kill them there is a chance they will drop a squirrel tear which is an artifact towards the ‘critter tears’ collection. Buying these from the auction house will not help towards your cheevo, you need to kill the squirrels and loot them yourself for it to count.
There are quite a few squirrels around the Rill Pond area of Freemarch at /setwaypoint 6596 5137 remember you can switch shard and kill more!
It took me about 20 minutes to pick up 5 tears just taking the route marked on the map below and spamming the macro!
Switch shard when you reach the end of the route to allow all the squirrels to respawn.