Creating a chicken run is often less about keeping chickens in and more about keeping predators out. As relatively harmless birds, chickens have a variety of predators including hawks, foxes, rats, snakes and mink. Many of these are smaller than chickens, so look for fencing options that have small openings to prevent predator encroachment.
Fencing made from galvanized wire provides long-lasting protection for your chickens. When buying wire fencing that has small holes, look for hardware cloth—which is a wire-based mesh, and not really cloth—small-aperture chicken wire or variegated rabbit wire. All are flexible, which makes them easy to install, and come in a variety of lengths. When cut with tin snips, the edges can be sharp, so make sure no raw edges face into the chicken run. With chicken wire, buy lengths with holes of 13mm or less. With rabbit wire, which typically has wider apertures, look for the type that has smaller holes at the bottom—where the chickens will be—and larger holes at the top.
Polyethylene netting is a less expensive alternative to galvanized metal wire runs, but it doesn't usually last quite as long. Fierce predators, such as coyotes, can tear the netting, but doubling it up helps prevent that. Bird netting can help fill in the top lines of fencing. It's not quite as durable as the polyethylene netting, but because most predators attack at or around ground level, you don't need quite as much protection higher up.
What Not to Use
While it might seem like a no-brainer to use any type of chicken wire for your run, wire with large openings lets predators such as rats and snakes crawl right in. Savvy predators such as raccoons reach inside wide openings and snag chickens, killing them from outside. The same applies with chain-link fencing: the holes are just too large. Stay away from split-rail or wood picket fencing for the same reason: it might keep your chickens in, but it won't keep predators out.
Since the idea is to keep predators out, build the run high enough to discourage predators that can jump, such as coyotes. Many of these animals leap more than 4 feet high, so build a run that's 5 to 6 feet tall for best results. This won't stop flying predators such as hawks, but covering the top will. Use the same material as the sides, or a game bird netting, to discourage flying predators. Some predators, such as foxes, dig under fences, so foil them by digging a trench about 6 inches deep along the fence path. When you install the fence, place the bottom in the trench and backfill it with dirt so it's unlikely a predator will be able to dig below it.
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