Hello All - I have just joined the board, and noticed this thread. Have been keeping poultry for over 30 years, and parents before me.
I always used to let all my poultry free range, with little trouble, as long as they were shut in at dusk, but as time has gone on the foxes have become more troublesome, and will sometimes take stock during the day even when someone is around! I wonder if urban foxes are less worried about humans, and even where I live, (in the open countryside) trapped urban foxes are often released to enjoy their freedom in the country when becoming too troublesome in the town.
I have found that electrified poultry fencing is safe against foxes/badgers, even when the popholes are not shut at night, though you must ensure that as the vegetation it does not short the fencing out.
People mentioned digging in chicken wire, this is effective if you do not dig it in straight down, but just under the surface of the soil, bend it outwards from the pen at 90 degrees and bury it so there is about 15" - 24 " of it level with the surface, but just underneath the grass. It is best to use the stronger smaller mesh wire for this, as normal chicken wire is too flimsy, and any determined fox would scratch through. Last year I made a large pen for ducks (foxes favourite meal) which was 6ft chicken mesh at the top and then overlapping 3ft small wire at the bottom, following the directions, as above.
I hope this is clear, but it is difficult to explain without waving ones hands about.
The other way is to have 6 ft chicken mesh pens, with a single stand of electric wire about 12" away on the outside of the pen at about 6 -9" high from the ground, which prevents the fox/badger from digging under the chicken wire. Foxes can easily jump 6ft, but generally need something to land their feet on, so never have wood at the top of the wire.
And don't forget badgers love to eat meat and will regularly dig out rabbit nests. They are much stronger diggers and biters, but again the electric fence seems a deterrent. My original hen house had some of the smaller stronger wire mesh stapled to the bottom 24" of my chicken house to stop this. Many poultry houses are made of quite flimsy wood.
If you can, site any housing closer to the middle, rather than the edge of the pen this seems to help, as the fox cannot smell the poultry at such tantalizingly close quarters.
Hope I have explained this properly. The main thing is to keep them shut in before dark, and be around and active in the area during the day. I have also heard that man-pee at strategic points is also a deterrent, but cannot vouch for this!
All the best
Susan