1. LOVE THEM!
The first, best, and most important thing you can do for your chickens is love them. If you do that everything else comes naturally.
2. HOUSE THEM PROPERLY!
It takes a very special person to choose to share a house with chickens. Most people build chickens separate quarters. Keep these tips in mind when designing a chicken coop.
Comfort
Happy, healthy chickens must be comfortable in their home. They must have space to move around, get away from bullies, and breathe fresh air. Look at the space you are planning on giving your chickens to occupy, and picture yourself as chicken sized, living in there. If it reminds you too much of a crowded college dorm, add more space. Provide feeders and drinkers that are convenient for the chickens to use and you to fill. Provide roosts for sleeping on at night(wild chickens roost in trees at night). Make them as wide as the chickens' feet(at least 2 inches) for extra support. Provide private nests with hay and cedar chips(to discourage bugs) for your hens. Make sure there are enough! One for every four hens should be plenty.
Protection
Many wild animals like to eat chickens. If there is a place on your coop where you can reach in and grab a chicken, chances are something else will break in through there. And don't forget about things that climb. There should be solid walls or wire mesh all around your chickens, and this is most important at night. I keep chickens in a moveable range confinement coop, where they are free to be on the ground during the day, but are still protected from roaming dogs and such. At night they are closed up indoors in a coop which is off the ground to baffle diggers. By all means, if you hear chickens making a ruckus, get out there as fast as you can and see what the trouble is. If you keep chickens outside, be sure there is a good place to get out of the rain or sun. Other considerations may have to be made if you live where it gets really cold. To protect against disease, make sure the coop is easy to clean. Holding to high standards of cleanliness is one of the best barriers against disease.
3. FEED THEM WELL!
My chickens eat a basic diet of scratch grains and rabbit pellets. I feed rabbit pellets because lay ration contains dead ground up chickens and often lots of weird chemicals and stuff they don't need. A good supplement, if you can afford it, is that pelleted food for caged birds like parrots. This stuff is so good, my vet tells me, that people could live on it. I've tried it, it tastes like a fruity, whole grain breakfast cereal. In addition, my chickens get bread, all sorts of veggies and fruits, and pasta. Their favorites are leftover corn cobs, apple cores, squishy tomatoes and lettuce. I'm trying to start up a cricket growing enterprise too, because they just love juicy bugs. Don't give them roaches and things that may have been poisoned, though. Chickens that live outdoors pick up little rocks that they store in their gizzards and use as teeth to grind up food. You can buy grit to give to them if you think there are not enough rocks on the ground for them. Oyster shell, which is a good source of calcium, is also a good supplement to give chickens.
4. UNDERSTAND THEM!
There's Something about Roosters
Roosters don't get along with each other. You can vary the living arrangements and give them plenty of space to reduce fighting, but they will still do it every now and then. The best arrangement is one rooster and some hens. I have heard that three or more roosters won't fight so much, but my experience doesn't support that. The best solution besides giving excess roosters away is more space and put in dividers so they don't have to look at each other so much. Separate feeders and waterers are a good idea, then they can stake out their own territories.
There's Something about Dustbaths
If you keep chickens on the ground, they will take dustbaths. If you don't, you should give them a sandbox so that they can. It's important for their personal hygiene, and they really seem to enjoy it. It's fun to watch, too!
Chicken Watching
Spend time watching your chickens. You can then recognize sickness and social problems early. Don't be afraid to bring a sick or injured chicken in the house. Refer to the health links on my main page, or your library for help. But since companion chickens are rare, be prepared for plenty of unhelpful information. When all else fails, tender loving care often does the trick.