We have had a tree swallow build a nest in one of our boxes, this is the first time I have ever had a bird nest in our backyard and I have loved watching her every morning. She had laid 5 eggs and I've been watching her come in and out of the nest then start to remain in her box for longer periods of time. Every once in a while I will peek in and she'll be sitting on her eggs, I try not to do this too often because I don't want to scare her. But the last week here has been cold and rainy. The dad is no longer coming to check on her, I haven't seen him in probably 3 days now.. but my concern is that the mom is also gone.. I haven't seen her all day and when I opened the box one of her eggs was cracked open with part of it missing. I can't find the other part of the shell anywhere in her nest nor on the ground so I wonder if a predator got in? I know there is nothing I can do, but her other eggs are still in there and I am heartbroken that she seems to be gone Does anyone have any advice or insight to offer?