What is birdie short for?

"Birdie" is a term commonly used in golf to refer to a score of one stroke under par on a hole. It can also be used more generally to describe any score of one stroke under par on a golf course or round. The origin of the term is unclear, but it is believed to have come from the early 20th century American slang used by golfers. The term has since become widely accepted and used in the sport of golf around the world.