In Morocco's High Atlas mountains, shepherds Hammou Amraoui and his son hardly need words to speak. Across peaks, they whistle at each other in a centuries-old language, now jeopardised by rural flight.
"The whistle language is our telephone," joked Hammou, 59, the elder of a family known for the tradition in Imzerri, a hamlet in the remote commune of Tilouguit, about a two-hour drive from the nearest city.
