We typically use verbal praise as a reward. Mainly, I don't want Kiwi filling up on "treats" and not having room for his real food just because he's being a good boy. Secondly, I don't always have a treat nearby every time he does a positive behavior I want to encourage. He gets rewarded with a very excited "good boy!" and acknowledges his praise by shaking his tail (very cute). I prefer verbal cues and praises personally, but if you really want to give treats, use small bits of your birds favorite foods. Kiwi gets treats in his foraging toys since it's a good way to reinforce self-rewarding play, which is usually chunks of granola, nuts and if he has a really difficult/new foraging toy, a chunk off a potato chip for some extra encouragement (he loves chips).