As an update to Ava's toy roundup I noticed another odd thing about her toys recently.
She has two of the same toy, similar to this. While the toys rarely find their way inside her cage, I noticed that she put two toys that were the same into her cage. All the others stayed out. After I saw that I noticed she took one of the balls out, played with it a bit, then hopped away, only to return and replace the ball in the cage.
Next week we're going to try some calculus. I'll keep you guys updated.