Gluing Twigs to a Mirror?

I have a mountain condo where I recently decorated the edge if a large mirror with twigs and sticks gathered from the area. It fits perfectly in the dining with its rustic decor. The problem is they keep falling off. I've used silicone and a glue gun. Some stay on, but every few weeks I lose a few and have to reach for the glue gun again. Any ideas?

By J E L