My silkie hen has four eggs all set on the same day. However, one chick hatched on day 18, another on day 19, one on day 20 (today) and the last one looks like it may hatch this afternoon or tomorrow morning. Since the eggs were all set on the same day, I am baffled as to why this may be happening. I put food and water in the nest with the mother and babies and she shows no signs of wanting to get up yet, but I'd like to avoid similar situations in the future if possible. Does anyone have any idea why this might have happened?