A neighbor recently reported that he could hear squirrels in his attic. The noises were most pronounced at dusk and at dawn, so I know they were gray squirrels, not flying squirrels (which make noise in the middle of the night).
I went over to look at his house and immediately noticed the big shrub growing next to his carport.
It was a super-highway for squirrels up to the attic louvers!
We chopped down the camellia to a manageable height and the attic noises were eliminated.