Ok, so I suspect there is a rodent in our attic, probably a mouse. I saw one outside along the house one day a while back and I have heard the scratching of its feet through the wall. Upon inspection of the exterior of the house, I think I found where it could be getting in. I also inspected the area of the attic where I suspect it is nesting and found some evidence there.
I think the mouse is coming and going, having noticed hearing the scratching noise at a particular time (around 10 PM) on cooler nights only, thinking that maybe it was coming inside to the nice warm attic insulation. My wife mentioned that mice are noctural though so maybe it is actually LEAVING the attic and going outside to search for food. I also have not noticed the noise when it is warmer outside so maybe it is only coming in when it is cooler?
Anyway, I have a plan to seal the holes, but I am trying to figure out the best time to do this in order to ensure that I don't seal the rodent INSIDE the attic. I want to obviously get it sealed up once it departs.