"The Island of Mull, island of the great mountains, the sunny island in the midst of the sea . . ."
Translation is not quite correct, but close enough!
That is so lovely! The last portion that they hummed without words made me focus on the melody, and I was reminded of the sounds of the noted 19th century Scots-American composer of popular songs, Stephen Foster, who wrote many favorites of a bygone time:
Beautiful Dreamer
Camptown Races
My Old Kentucky Home
Oh! Susanna
Old Folks at Home
I Dream of Jeanie with the Light Brown Hair