Curious question of the day - flamingos

I think I've decided that I'll post random questions on a regular basis from now on, to see what kinds of interesting answers people come up with. In some cases, I'll also just ask random factual questions.

So, the question for today, and it's probably only a factual question, is why flamingos have a tendency to stand up in one leg instead of two.

By the way, even though the question asks for a factual answer, feel free to be creative with your answers. Most of the time I think I'd rather read an interesting answer than a correct one.