I took a walk last Sunday along the Des Plaines River in Thatcher Woods. I was surprised to run into a fox squirrel I’d first seen last autumn. I say surprised because she’s blind in her left eye. I was certain she wouldn’t last long in a forest filled with coyotes, raccoons and silent and swift Cooper’s hawks. But there she was, sitting on a fallen branch. She couldn’t see me, but as soon as she heard me, she wheeled around to use her good eye.