I got the nickname Falcon as a child after doing a science report on raptors and falling in love with the idea of falconry. It's funny but it's followed me all my life ie: my 1st car was a 62 Ford Falcon, my hunting bow is a Falcon Flame etc etc.
When I 1st got online I used my natural nickname only to find out there are a gazillion people nicknamed Falcon but I've stuck with it since all of my online friends know me 1st and foremost by it.