Once you press the Challenge button on the main screen, there will be several surprises: the opponent for the challenge will be unknown, the national park where the challenge takes place will be randomly chosen from the unlocked ones, and even the birds will remain a mystery. Typically, the system matches opponents based on the number of trophies earned by both players up to that point. However, it is necessary for both participants to have access to the same national park.
Therefore, if a new park has just been unlocked, your bird collection might not be complete, and the random selection for the challenge could turn out to be more challenging. To avoid this, you can open new bird packs, purchase special offers, and participate in events in the national park.