From the Super Mario Wiki
Bird (バード Bird) is an elite male golfer in Mobile Golf for the Game Boy Color. He is the champion of the fourth tournament that one must defeat in singles. Along with Bean, Rozary and Powert, he is one of the four human golfers the player must face in four singles tournaments, similar to the fashion of Mario Golf for the Game Boy Color. His Mario Golf counterpart would be Gene.
According to his profile on Camelot's Japanese Mobile Golf website, Bird is an ultimate golfer who is known for having constant birdie streaks whenever he plays. His prowess is excellent and he leaves his opponents speechless with his amazing golfing skill. His shot flies straight and true like his namesake, and he will not show his opponents any mercy.