There is no way to check right now, but there are warning signs. If it doesn't have the Kalos Pentagon, then it comes from an older game, where it was easy to hack Pokemon. If it has a big series of max IVs, it's probably hacked (ie a 6IV Metagross or a 5IV Latias).
Tufted Titmouse are regulars at backyard bird feeders, especially in winter. They prefer sunflower seeds but will eat suet, peanuts, and other seeds as well. Find out more about what this bird likes to eat and what feeder is best by using the Project FeederWatch Common Feeder Birds bird list.
It's got a little tuft on its head and is a soft grey with lighter underside. Tufted Titmouse is a possibility, but I don't know for sure. I've got him in the cat carrier out on the deck with a paper towel in a plastic bowl for a nest. He's very vocal, and he's been eating a little bit of the formula I used for raising the robins. It's supposed to be good for any orphaned birds.