It's very simple. Through the programing genius of Alex the WP portal is capable of looking into your soul. After it does so, it compares your true essence to over 10,000,000 birds animals and plants. It then identifies which one is the closest match to you. But be wary, WP also can see into your thoughts, and knows what you do when you think no one is looking.
That *OR*
it just has to do with how many times you have posted in the forums.