Do you think it's a grizzly or a black bear? I've never had to deal with bears, but I thought they slept through the night, napped during the day, and hunted at dusk and dawn. I would be afraid of having a bear that close. Do you have a rooster? If the rooster attacked it would surely escalate the situation. But then again, I'd assume the bear would kill them and eat them anyway if it could. Gosh, I'm sorry you're dealing with this.
That sounds really stressful! I can't imagine trying to deal with that. Have you tried any deterrents to keep the bear from trying to get at your chickens? I've heard that the smell of ammonia keeps them away, but I haven't had a reason to try it myself.
We have black bears here too. They do roam around at night. We haven't had any issues with them getting our chickens or any livestock. Our garbage doesn't stand a chance against the bear, they tear into that a couple times a year.