This morning while I was sleeping I heard this strange sound coming
from one of our exterior drywall. It lasted about one second or so
and sounded like wood cracking (or someone tearing apart wood).

It sounded too long to be a typical wood expansion noise due to
temperature change. (This is a north facing side, and does gets a bit
of sun very early in the morning). The temperature outside is slightly
chill, but not like winter cold.

Could a rodent be causing this type of noise? Rotted beam? Sinking
ceiling? Nothing looks out of the ordinary from the inside or the
outside. This is the 2nd time I've heard this noise and both times it
sounded very abnormal. The window was closed so this is not something
from the yard/outside!

Thanks!

Raymond