There are three pets available for gaining by completing the Deliveries: Monkey, Red Panda and Panther. Together they form a Jungle Collection that provides quite the bonuses in the game:
Each pet can be obtained through the collecting of the Puzzle pieces.
You can randomly receive Panther Puzzle pieces and Red Panda Puzzle pieces for opening Delivery chests. The higher chest quality is the more is the chance for you to receive a high-grade reward such as a Puzzle piece.
Monkey Puzzle pieces can be received for filling the Delivery totem bar and gaining Reputation Potions