They will act like they are starving even if they have an abundance of food and a rich environment.
I were in your shoes, instead of corn, I would add clutter as in things for them to hop onto, to fly up on, to hide under, to sit behind. There are several threads and articles with lots of...
Half a cup of corn per day each is about 3/4 of their diet. That is way too much of a food that is too low in protien and various other nutrients.. A tablespoon is about 10% of their diet and that is about the maximum recommended for all their treats. That still isn't as nutritious as just their...