I suppose it could be that, but check around the area and see if there's something they could have gotten into. It doesn't make any sense to me why they just die out of the blue like that.I’m pretty sure it’s not because of that though. Because only the 1st chick got pecked in the beginning and then when I reintroduced them the next day she started really becoming a mother and I could tell by her body language and sounds that she understood the chicks were hers. I even supervised for almost a whole day when I reintroduced them. When she went outside with them, she just called them and let them crawl under her. She only pecked them gently to help them under her.
The other reason I am pretty sure she had nothing to do with this is also because last year I had a agressive hen towards her chicks and she ended up pecking two of them hard until I saved them but they both survived without any treatment and became healthy roosters.
I’m really stumped as to why they died. Could bacteria from a broken egg do this? My hen accidentally broke a developing egg a week before hatch day and some substance got over the other eggs.
I’ve had other broodies in the past do this too and no chicks got infected though.
I've hatched nearing 500 silkie chicks this year alone, and grew out about 20% of those, and never lost one. I really want to try help you figure this out as it shouldn't have happened. Sure, one may not make it for whatever reason, but all three? I'm so sorry though!