It's a tip just as helpful for animals as it is for humans: when in danger, puff yourself up to make yourself look bigger. Fish do it, cats do it, and even the truly weird frill-necked lizard does it. And if you can't puff yourself up, then just get some friends so all of you look bigger. That's the message behind this photo, except these flamingos have just really taken it to the logical limit.
How they've managed to arrange themselves into a giant version of themselves, we'll never know. It's just one of those unfathomable mysteries, like the Nazca lines in Peru. Maybe it's completely unintentional - one of those freak occurrences of nature that just so happened when a photographer was flying by. Or maybe they're far more intelligent than we give them credit for.