We have both grass snakes and adders here, with the damp ground and wild areas. Never bother us, except when the postman accidentally ran over a large adder, OH moved it into the undergrowth to allow it time to recover, when he went back up an hour later, snake dead. It had crawled back onto the road for the warmth and had been flattened by a tractor tyre.
Re chickens - not sure about tiny chicks, but when we had an adder nest the damned hens found it, raked it out and bit off the heads of the tiny bootlace babies.
We have a large colony of some exotic local frogs in our pond, and any snake which would eat those would be welcomed with open arms. At 3 am their singing could drown out a rock band.