A slur is a curved line above or below two or more different notes. It indicates that the notes must be played smoothly (called legato). To play legato, only tongue the first note of the group and keep blowing while you change your mouth position for the other notes.
This Australian convict song has a mournful sound and should also be played slowly with a strong, even tone. It is written in ^ time and covers a range of one and a half octaves. This song contains many slurs, which helps create a smooth, flowing sound. Slurs can be used any time for expression even when they are not indicated in the notation.