Has anyone done any studies into if ferrets converse with each other using ultrasonics? Beeing small, they should have no trouble hearing sounds above 20 kHz, but do they make them? To me, they are practically silent most of the time, and when they aren't they either hiss when frustrated or yip when happy. My reason to believe they may produce other sounds, is that they very quickly learn to understand what I say -- faster than dogs even -- which seems to indicate that they consider sound as a form of communication, more complicated than hiss/yip. -- Urban Fredriksson [log in to unmask] Stockholm, Sweden [Posted in FML issue 0315]