Hi! I have managed to record it after a sleepless night of chirping ! have had guinea pigs for many years and have only had two who have chirped, both girls, but they rarely did it. It was always in the hours between midnight and about 4am. At the time, I thought they may be cold, very trance like and eerie too! However I now have a girl coming up five months old, who is quite confident, rumble struts and mounts the others about once a month, nothing vicious, so I am starting to think it could be a season/dominance thing as it's her time of the month!. This seems to be when she does it, and it is all night and loudly. So I am starting to think it could be a dominance thing. Unfortunately I can't seem to attach voice recorder which is quite annoying but I will try and find a way.