Building (and Maintaining) a Wildlife-Proof Chicken Coop
An adequate chicken coop keeps your flock safe from predators such as raccoons and opossums, prevents wild birds like jays from coming in looking for eggs and getting themselves stuck, and excludes rodents. This way, you can raise healthy and happy chickens while still allowing the rest of your yard to be a haven for wildlife.
Wildlife-proof chicken housing usually involves an enclosed coop attached to an open outdoor area. During the day, chickens can roam freely between the two areas, and at night, they are locked inside the coop to keep them safe from nocturnal animals such as raccoons, opossums, and skunks. Essential elements such as a feeder, waterer, roosts, and nesting boxes are enclosed inside the coop so that the outside area can be "optional."
The Coop
The coop must be built out of sturdy materials so that curious wild animals cannot get in. One option is to start with a pre-built structure such as a shed or aviary, and modify it for your needs, or even enclose a built-from-scratch coop in a secure aviary. Otherwise, you can build the "frame" of the coop out of wood and enclose all sides (including the top and bottom) with plywood and/or quarter-inch hardware cloth. Don't use larger mesh hardware cloth or chicken wire, as quarter-inch or smaller holes are necessary to keep out rodents.
The Floor
Some enclosed coops are raised on posts, and have a wooden or mesh floor that is above the ground, while others are built so that the ground is the floor. If you choose the latter, make sure you line the ground with mesh to prevent animals from digging under. Chicken wire is fine for this purpose, as rats are unlikely to dig underground to gain access- lining the floor is mainly to keep out larger animals like skunks. In addition to attaching the mesh to the walls of the coop, lining the edges with bricks can provide extra security.
If you are building a raised coop that is self-contained (not in an aviary or other enclosed structure), build the floor with wood, not hardware cloth or mesh. This makes it more secure against raccoons, which have been known to reach through mesh to grab chickens by the feet. The coop will still need ventilation, but windows screened with hardware cloth are more secure than a ventilated floor.
The Roof
The roof of a wildlife-proof coop should ideally be constructed out of wood, sheet metal, or another sturdy, solid material. This not only keeps the chickens dry when it rains, but also adds extra protection against climbing predators such as raccoons. Build the roof with a slant to minimize damage from water pooling when it rains, and to make the top of the coop a less desirable place for rodents to live. Make sure that there are no gaps between the roof and the walls (as might occur with a material such as corrugated metal) so that rodents cannot get in.
The Door
The most important feature of a chicken coop door is the ability to close it securely at night so that wild animals- mainly raccoons- cannot get in. If conflict with raccoons is especially common in your neighborhood (e.g. raccoons knocking over trashcans or entering other chicken coops), you may want to use a padlock. (For ease of access, keep the key on a string tied to the door or get a lock with a combination.). Normally, however, any latch that takes more than one step to open should be fine. For example, you can use a gate latch designed for a padlock and clip a carabiner where the lock would go. (See image on right). Although raccoons have proven to be able to open complex locks in experiments, a wild raccoon looking for a meal would not go through the effort.
In addition to security against raccoons, another consideration with coop doors is wild birds. To deter jays and crows from going after the eggs, and to keep other birds from accidentally getting stuck in the coop, hang strips of burlap, canvas, denim, or another heavy fabric from the top of the door. You may need to start by tying these "curtains" open so that your chickens know that they can go through them, but eventually they will ignore the fabric. A dedicated jay or crow might still be able to get in, but you can minimize the chance of this by locating nesting boxes in a place where the eggs cannot be seen from outside.
The Run
Many chicken coop setups involve a free-range area attached to the coop, where the chickens can roam during the day. If you have a large yard, it is best to restrict the chickens to a specific, fenced run- not only to protect your garden from them, but also to make it easier to get all the chickens inside at night. Avoid locating the run around dense greenery or other areas where nocturnal animals might be living. You don't want a chicken to accidentally wake up a wild animal during the daytime.
If you are concerned about raptors or other diurnal animals going after your chickens, consider building a run that is completely enclosed with chicken wire, including the top. As long as you lock the chickens inside a secure coop (separate from the enclosed run) at night, the enclosed run does not need to keep out raccoons or rodents.
Avoid putting food for your chickens in the run, as this can attract wildlife and make them accustomed to an unnatural food source. Also, keep an eye out for chickens laying eggs in the bushes, as eggs left outside can also attract animals.
Ongoing Maintenance
To ensure that your wildlife-proof coop stays that way, plan to inspect it from time to time and fix issues that might allow wildlife into the coop. Some things to look for, and fix, include:
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Potential entry points for raccoons and similar sized animals, including places where such animals may have tried to dig under the coop.
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Evidence of rodents living in or accessing the coop, such as droppings, bits of food and debris stuffed into crevices or found in other odd places, and gnaw marks.
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Any holes or gaps you can fit your finger through- these can allow rodent entry. For small, individual holes, stuff steel wool in the hole and seal it in with spray foam. Alternatively, cover the holes with hardware cloth secured with nails. 1/4 inch hardware cloth is sufficient to keep rats out, and 1/8 inch may be needed to keep out small mice. For larger holes, hardware cloth is the best barrier. If your coop is constructed out of chicken wire or hardware cloth with holes greater than 1/4 inch, cover these areas with 1/4 inch hardware cloth secured with zip ties.
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Wildlife-blocking features that have lost their functionality and need to be replaced. For example, denim curtains over doors degrade over time, and will need to be replaced in order to keep out jays.
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Overgrown vines or other greenery on or near the coop. Trimming vegetation away from the coop makes it less attractive for rodents since they won't have as direct of a path to the coop.
It is good to do this inspection every few months, or more often when your coop is newly built, to catch potential problems.
If you find rodents living in the coop:
First, thoroughly inspect the coop for access points, and fix any that you find, so that more rodents cannot get in. Removing the existing rodents alone will not solve the problem, as the steady supply of feed will just attract more.
Next, trap any rodents that remain stuck inside, either with snap traps or a livetrap designed for rodents (no mesh larger than 1/4 inch). If you use a livetrap, release the rodents right outside the coop, not outside your property, since releasing animals into unfamiliar locations can be inhumane (it makes them vulnerable to predators and conditions they are not used to). Baits that work well for catching rats and mice include peanut butter, honey, and avocado. (Don't bait the trap with chicken feed, since the rodents already know where to get that). DO NOT use poisons or glue traps- not only do they cause a cruel death for the rodents, but they are not safe to use around your chickens. Even snap traps should be used with caution, and not placed anywhere a chicken can access them, because they could seriously injure a chicken's foot if stepped on.
Remove any existing evidence of rodents, such as droppings, nests, or middens (piles of seed hulls and other discarded pieces of food). Continue to monitor the coop for further evidence of rodents, and if you find any, repeat the inspection to see where they are getting in. A motion-detecting wildlife camera can also help identify access points.