She's 10 months old but I noticed this behavior out of her months ago. We live in town and have a large fenced in back yard.. To my knowledge there has never been anything other than birds and squirrels in her backyard
She loves to be out there during the day- would stay out all day if I would let her, but when the sun goes down she doesn't want any part of being outside.
We have a screened in back porch with a light, but she still isn't crazy about going beyond that.
I don't know why she is so spooked to go out...