You are correct. A one foot fall will not bother the chick at all. Mine normally hatch in nests higher than that and the broody hen has no problem getting them down when the time is right.
If a chick falls out, will he hen retrieve it? You are dealing with living animals. While I consider it not likely at all that the hen will retrieve it, I guess anything is possible.
What are the chances of a chick falling out to start with? How big are you nests? How does the hen sit in there? I once had a hen hatch in a cat litter bucket with a top 7-1/2” x 11-1/2”. She was sitting right on the edge. The first baby chicks that hatched would climb up on her back and when they fell off, miss the nest. That nest was about three feet off the coop floor. The hen stayed in the nest. Several times I picked chicks up off of the floor and put them back in with Mama. I retired that nest after the hatch. It was OK for them to lay in but not to hatch in.
I don’t see much of a lip on your nest. Since the hen has not scratched bedding and eggs out it may not be as bad as it looks to me, but I agree with Centrarchid, you need to put some type of lip there. I’d suggest something like 3” to 4”. As long as the hen is sitting back away from the edge it is highly unlikely a chick will fall out. But you are dealing with living animals, about anything can happen.
Personally I’d not build a fence or anything like that. I don’t. But you might be surprised at how mobile a newly hatched chick can be after it dries of and becomes active. If you are really concerned about it, build a series of steps maybe 3” to 4” high from the floor up to the nest. Or make a ramp. The hen will almost certainly call to the chick if it falls out. There is a fair chance the chick will make it back up to the hen.
How dangerous are the other hens to baby chicks? There is no question there is risk. A lot of it will depend on the personality of your hen. Mine usually don’t go out of their way to bother a baby chick, even one not protected by its mother. But some will. I cannot come close to telling you how high your risk is. But when my baby chicks fell out of the nest, the other hens were going to and from the other nests to lay and never bothered the chicks.
There are all kinds of things you can do. If it were me, I’d make sure there was a decent lip on the nest and do nothing more. But others would handle it differently.
Good luck! It will be a good hatch!
