I have a 5 year old tabby boy - neutered. He's normally very quiet but I've noticed that when I let him out on the screened-in front porch and the cat from across the street comes over and looks at him through the screen, my cat meows - a very throaty meow, over and over again. He almost sounds mournful, like he's crying! He isn't hissing or scratching at the screen so I don't know if he's upset that another cat is there or he's sad because they can't play together or if he's angry or...I don't know. Any ideas from other cat owners? I'm just curious. The other cat is a male, I think.