Field Rat is a foe in Borderlands 2
These are faster, tougher and more evasive Rats. They still very much will grab and make off with whatever loot they can. They try to stay back from you, attacking with their assault rifles from a distance. They will, if possible, move in for a quick melee strike using a long leap. This has sizable knock back. If they happen to pick up a shield, they can sometimes equip it. Like any other Rat, they will stop to pick up any loot in front of them.
Headshots, leg shots, fire.