What type of bear? We have to protect against black bears, and thankfully not against grizzly or kodiak...you have to give careful thought to construction and you will need a roofed run for those days when you can't risk free-ranging. Be sure your framing materials are substantial and that your door can be protected with a locking bar.
Another thing you can do is to relocate your compost FAR from the coop, and to keep any meat/fish/poultry/bone leftovers in the freezer until pickup day. Bird feeders should be far back, too. But really, with bears already using your property, separation is the only way to keep poultry.
Click on my home page if you want to see how we are coping. We have not had a direct bear attack, largely because we have many farming neighbors whose poultry are, um, available (free-range). Ahem.
