Shame man, that's so sad, especially that your son was there. Maybe she already had something like you said, it's not really a way to know if you haven't been around where they hatched. I also know that little birdies like this are sometimes attacked by mice looking for an easy meal, but if they are in an enclosed area, doubt that's a possibility.
I'm so sorry but I wish you all the best of luck for the days forward. They don't stay that size for long, so enjoy it.
And yes, Chirpy is definitely a word. 🐥
Yeah and I didn't even bother to check her feet when we picked them up. We just assumed they were all good.