Hi Rossco. The instinct in poultry is always to roost in the highest place available. (short of thirty foot up in a giant ash.) Is your run covered? If not I wouldn't think they'd be safe outside. Foxes can clear any height of wire fencing up to nine foot or so, and even then... It is difficult. You might be out there catching them every night! You could try tacking floppy wire around the top of the house to make it difficult for them to fly onto the roof, but the best way is always to roof over the top of the pen with more chicken wire. I put props up every so often to hold it up in the centre. That's quite easy. The painstaking part is lashing the lengths of netting together to make a continuous canopy. For this though your groundwork also has to be good. At least eight inches embedded.