I bought four blue eyed cardinals a few weeks back. They are full grown. When i got home i noticed there was some thing floating in the bag that was not there before. It looked like a egg sack. I by no means am trying to breed them, just trying to understand their behavior. Now it seems like one cardinal is always being protected. It stays inside a cluster of tonga branches that the cardinals now call home, and only comes out to feed. The other three just hover around and take turns darting in out. I'm wondering if they are maybe getting ready to breed again?