It's much more than just a birthright. They're programmed to mark territory, claim it as their own. It's a greeting, statement, or a warning.
People say dogs can't speak; well, I disagree. They use their bladders to talk and their noses to hear.
I suppose Fletch really thinks the world is his to piss all over. He certainly acts like it, and marks accordingly. He's just doing what comes naturally to him.
Peeing on everything is not something I should try to emulate, literally. But the model intrigues me. Treat the world a little bit like it's yours. Let others know you're there, that you exist, and that you care. Tell the world that you're present, that you're around, that you've left your mark.
"Occupy the space you occupy." — Adrienne Rich