The current frontrunners are
1) Very large rat
Every night for the last week we are woken up at 4AM to loud scratch noises, like a cat scratching around the litter box, heard clear as day through our bedroom AC vent (near the ceiling)
Except it's not the cat, because our cat sleeps in our room, and I looked at her while the noise was happening.
This just started recently as it began to get cold outside. We think something is nesting in our house, but we have no idea where
We think this may be a long term resident, because the day we moved in, we found some animal feces and urine upstairs that neither of us could identify as belong to one of our pets.
So now we may think it may be that animal returning home.. we scared him away when we moved in, and now he's back since it's getting cold
I don't even know where to start. Physically where could he be if he's heard so clearly in the AC vents? We've looked around many times upstairs and seen no traces at all of the intruder. Just the noise. Every night for the last five nights.
Looking for ideas on how to get rid of it. I'm worried about mousetraps since the cat might set them off.