The male uses a fixed and unmistakable pattern of musical notes in its call. The notes are loud and normally divided into two stanzas – the first with 5–6 trilling notes rising and falling, followed by 4–5 notes rising up the scale and ending in the highest note. Birds use the same song year after year, with progressively small changes, with the result that the song sounds very different after 4–5 years. The male’s call is a valuable tool in detection and identification of the bird.