Snakes are territorial. Red bellies have territories that range from 0.02 to 40 ha (0.05 to 100 acres) so relocating is problematic. It likes shallow water, debris, frogs, small mammals so I would be looking at removing anything the snakes would find attractive from around the chook pen: hollow logs, puddles of water, swampy ground, tall or thick grass, large rocks, mammal burrows. Put a wire floor under your run too as they can burrow.
They spook the chooks & while I'm not frightened of snakes I prefer not to have to handle them.
