Good Friday Afternoon That other guy,
Small black snakes can harm or even kill your chicks considering the chicks size, a snake can 'constrict' the life out of a younger bird while trying to swallow it. And even if the snake can't swallow the bird, the snake can still suffocate it trying...
Amen, just as HappyHensFarmWV said in post # 6, think 'fortress' in planning your run. You can even buy light gauge (12 1/2) chain link fencing, 35.00 for a 50 foot roll, then you can get by with using 3 foot hardware cloth on the bottom. (Hardware cloth is 20.00 for a 3 foot by 25 foot roll)...