pretty sure, and as others have noted, smell is probably the primary sense. i have a couple female neighbors she adores, and when they're nearby/coming home, sh

pretty sure, and as others have noted, smell is probably the primary sense. i have a couple female neighbors she adores, and when they're nearby/coming home, she whimpers excitedly before i can hear anything. on the other hand, with a couple male neighbors she's slightly worried about, she'll do more of a grunt/growl. but visual, and even auditory, cues are also used. size, posture, stance, and gait, are all pretty good (but not perfect) indications of human gender. she's alerted on ambigously dressed people over 100 ft away who were walking in a lumbering/macho way, but ignores or sometimes wags her tail for those who don't move that way. edit: should note that sensing potential aggression/danger is probably a large component of this behavior too.