The call that kept catching me off guard was that Poorwill. other than that I've been able to tell the difference between calls of mammals vs owls. I have hands on experience with a screech owl and can pick that one out She made an array of noises depending on her current mood and/ or what she was trying to convey. Actually a pretty clever bird. I also have been monitoring 3 Barred owls over the last year and a 1/2. Also an awesome and interesting bird.