It is amazing how much noise the smallest of things can make. I had a couple of trips to Mwanza in Tanzania for work, and in the evenings at the resort we stayed at there were the most incredible high pitched pinging noises in the evening.
Went exploring the grounds, and it turned out to be tiny frogs about the size of the tip of my thumb - but sooo loud 
:
(I think the one I found was off shift as soon as they saw the camera light 
)
