When Grif was younger she would make a chirping noise. She chirped almost the whole way home when we got her. If I had the volume on my camera she would chirp every time it beeped. So cute! But she only did that for the first month or so when we got her. I have never heard it from my other pacman Loki though. I'm not sure exactly what it is, but it definitely isn't a mating call!