Animal mobs Minecraft, chicken constantly flap, mob pushing mobs threw walls.

Chicken flap their wings constantly even when standing still. Animal mobs ramming other animals mobs into solid block to die. and into no solid like fences to escape/ there are no steps this is observation of 2 hours on the new snapshot.
Also crops uproot them selves at night if under a tree and at mature level. adding lights round crops stops this. so a light level problem?