Birds have non-muscular tongues; also, they do not have much saliva in their mouths. Hence, the chances of peanut butter getting stuck to the roof of their bills, are minimal. You can mix crunchy peanut butter with raisins, cornmeal, cornstarch, wheat oats, bird seed, crackers, etc., to make it less sticky, drier, crumblier, and easier to swallow.