Ok, upon review, it is not the "wolf whistle". If this in fact is the wolf whistle: https://www.youtube.com/watch?v=Iz0vV8DSsDo

Ive uploaded a piece of the video that was posted by a member on FB. Another person has confirmed they also have the exact same chirp...
Have a listen (sorry for the loud music, video is not mine):
https://www.youtube.com/watch?v=3OCp09CqqyE