I have a broody silkie that I was able to obtain a few fertilized eggs locally for hatching. She had two eggs under her on day 22 yesterday. Late last night, around 11-12pm, I beleive one of the eggs was hatching, I could hear what sounded like an egg being cracked/zipped slowly and the hen was acting like something strange was going on underneath her. I went to bed, fully expecting a newly hatched chick this morning. When I woke up, no chick and only one egg was remaining underneath her. The second egg vanished without a trace. I keep her separate in a dog kennel in my garage, so no other chickens or predators could have bothered her. I have seen an occasional tiny field mouse in the garage in the past, but they are tiny, probably about the same size as a day old chick. What could have happened to the egg/chick. There are no egg shells or corpse left behind. Below is a photo of my setup: