I have a male cat and a female cat who tolerate each other when they are inside. My male cat goes outside on a regular basis, but I only allow my female cat outside if Im with her. She is very overweight and could not escape danger if put in the position. Although shes quite firey tempered, shes a slow mover, lol. Anyhow, a couple of times they were both outside at the same time, and once my male cat saw her, he crouched real low to the ground and attempted to sneak up on her. I could see the look in his face, it was like he didnt know it was her. He doesnt act like this when they are inside. Any ideas? Could he really not tell it was her? Did he think it was some other cat in HIS yard?