Even Squirrels can make an astonishing amount of noise when they get in the walls.

I also can never hear of anything like this without starting to think "On 16 July 1923, I moved into Exham Priory after the last workman had finished his labours. The restoration had been a stupendous task, for little had remained of the deserted pile but a shell-like ruin; yet because it had been the seat of my ancestors, I let no expense deter me..." (http://en.wikipedia.org/wiki/The_Rats_in_the_Walls)