This is my first year of FINALLY having a bird family move into one of my birdhouses. The Chickadees are about 1-2 weeks old. Yesterday I found a deceased baby Chickadees in the same yard as the nest but a good distance away. This morning I found another one also a good distance from nest. They obviously didn't fall out or get pushed out. Do you know what happened? Do BlueJays or Crows go after nests? What can I do to help prevent this. Also as of recently I have an issue with some rats. I do have an exterminator working on that but could they be the culprit? Any advice would be appreciated