Composed by Graham Townsend (1942-1998) in about 1960. The tune is said to have been named after a real budgie (presumably named Pat) who used to perch on his bow. This is a very bare bones transcription. The tune has evolved a bit in the last 60 years and is quite popular in Canada and elsewhere at the time of writing. In Scotland it seems to have grown a third part. There are quite a few versions on YouTube. There's a link to Graham's below. He's playing with Don Messer's backup band on this recording.