It isn't rocket-science

Article on fox-proofing hen coups, found on the net after 0.2 seconds of searching:

As manufacturers of mobile chicken coops, we've had many customers tell us about the brazen foxes in their area. Some come as close as their back porch in the early morning, and that's in a metropolitan area! I urge you to take appropriate measures to fox proof your chicken coop now, before you experience a fox attack in your own backyard.

Fox-proofing a mobile chicken coop

Fox proofing is undertaken slightly differently if you have a mobile chicken coop compared with a fixed chicken shed and run. Foxes mainly gain access to mobile chicken coops by digging under the edge of the coop and tunnelling under to reach your chickens. Even if you've got hard soil, don't think that a determined fox won't try to gain access.

One of the best things to do in this case is to wire a large mesh floor to the base of your coop. If it's attached to the base itself, it will be able to be moved along with your coop when you move your chickens to a fresh area of your backyard. Chickens love to have area to scratch, so you want to make sure that this mesh floor has large enough squares to still allow your chickens to scratch, but small enough that a fox won't be able to enter. We've found that mesh with 10cm x 15cm rectangles is ideal. If you stood this mesh upright, a fox could actually fit through, but when it's wired to the base of your coop, a fox will not be able enter the coop due to the angle of their burrowing.

The other option is to create a mesh 'skirt' around the edge of your coop. This allows your chickens more room to scratch, as there's no need to have the mesh under the coop as well, but makes moving your coop a little harder. We've tried both methods and the skirt is very cumbersome, but may be the preferred option by some.

Another important consideration is the strength of the mesh that is used on the sides of your coop. Unfortunately, some of the imported coops that I've seen on the market are made using very light 'aviary' style mesh. We've been told of foxes that have chewed through this thin mesh to gain access to the chicken coop. So it's worth checking that the mesh of your coop is of adequate strength to keep foxes out. We use mesh that 2.5mm thick and this works well. We've found that this cannot be damaged by foxes trying to chew through, or children who love chickens and clamber all over the chicken coop!

Proof-foxing a fixed chicken coop

If you haven't got a mobile coop, but a more traditional style coop that stays in a fixed position, you want to be sure that the run that is attached to your coop is fox proof. Most people with a traditional chicken shed and run erect a permitter of high chicken wire to form the run. This wire should have holes no larger than 80mm in diameter. As fixed chicken coops with runs, generally have no roof on the run itself, another important consideration is the height of the run walls. Chickens can't fly very high, but given a few 'stepping stones' inside your run such as a tree branch, they can potentially escape. Of course this height also needs to be high enough that a fox can't climb over. Generally fences of 1.8m high is found to be adequate to keep chickens in and foxes out.

When your run fence is erected, you also need to make sure that the wire at the bottom of the fence is dug into the ground, not too far below the surface, to a distance of about 50cm. As mentioned, foxes will dig to gain access to your chicken coop. When the foxes come across this wire time and time again, they'll eventually give up trying to access your chicken coop. Another way of achieving this barrier is to but something heavy like wooden or concrete sleeps on top of the mesh at the bottom of your fence.

By: Kerry Mundt