Chicken tractors (or chicken arks, as they're known elsewhere) are small coop-and-run combos that make it easy for you to integrate chickens into a vegetable garden or yard. Although you can buy pre-made chicken tractors, kits, and plans, all of these options are pricey, so many homesteaders will choose to build their own. Here are some factors to consider as you design your flock's new home.
Weight. Making the chicken tractor too heavy is the number one reason homemade chicken tractors fail. My father once built a chicken tractor so solid that it was too hard for one person to move, so the tractor sat in one spot for the next year. Chicken tractors keep your hens happy only if they are pulled to a fresh patch of lawn daily, so pay attention to the weight of your framing material. We usually use cedar branches or two-by-two lumber, but this tractor is built around the aluminum framing from a recycled awning. Use your imagination!
Shelter. Your chickens will need a very basic shelter to allow them to sleep out of the rain and snow. A tarp covering a third of the tractor with a stick underneath for a perch is quite sufficient for most climates, but my husband added a carpet flap around the roosting zone for additional wind protection in his $20 chicken tractor. (Remember to provide one linear foot of roost per bird on the perch.)
Doors. Access is an essential part of a chicken tractor. If you want your chickens to be able to free range some days and to be shut into the tractor on other days, you'll want to include a chicken-sized door at ground level. Even if your chickens will spend their whole lives in the tractor, you'll need a human-size door to allow easy access if a chicken is sick or hurt. Finally, a door into the nest box will make egg collection simple. (Don't forget to include one nest box for every five hens.)
Wheels and handles. You need some way to easily pull your tractor to a new patch of earth, which generally means some combination of wheels and handles. If you make the tractor light enough, you won't need wheels, which is good because wheels allow room for chickens to slip out underneath, unless you build a wheel lift system like the one shown above. Handles, on the other hand, are quite handy. I like to have a strong rope on each end of the tractor, connected at each corner into a loop. I step into the loop and pull the tractor forward as if I was a horse in harness --- easy and fun!
Winter accommodations. If you have a large enough garden and few enough birds, you can keep pulling your tractor to a new spot of earth all winter. However, a small yards will turn into a muddy mess in this scenario. One solution is to make a winter base for your chicken tractor and to fill it with leaves so your chickens stay clean and dry all winter.
Watering options. In our small tractors with just a few hens, we love Avian Aqua Miser Originals since they're easy to hang from the top of the tractor and don't take up any floor space inside. If you're raising dozens of broilers in a tractor, though, you might want to make a PVC chicken waterer like this one, or even a gutter-filled waterer like this one. No matter what you choose, focus on keeping the capacity low so the waterer doesn't weigh your tractor down, and do ensure you select a system that won't spill on uneven ground.
With these tips in mind, you should be able to create a top-notch tractor for your new flock. Good luck!