The solution we tried as an expermant has worked for 6 years now without any further preditor loss in the shed, Have had a few dog attacks outside). we put a light in the shed not a bright light, but one that lets the hens wake up enough to move away from preditors, (thye are sucessfull in attacking the birds at night because fowl are sound slepers and don;t move even when disturbed in the dark.), the light alows them to wake up enought o just walk away from the problem...plus has the added bonus of sustained egg production in winter. Our birds are pastured, and go out even in winter if the chose, but at night the usualy return to the shed to sleep, drawn by th light, and perhaps the recognise it as a safty measure too. only the turkeys refuse to go in in good weather, but as soon as the snow covers their roose, they too submit to the shed safty.