I suspect
@Andy the Sheep is able to tell us more about it
Thank you Jakko for the "assist"
Well, the feathers originally, since 1836, were wood grouse's; today they are synthetic unless you want to spend some times in jail an pay a very consistent fine for hunting a protected bird
They are worn on the right side of the hat/helmet in order to shade the aiming eye and that's why the hat was, and still is, worn "at 23 o'clock" that is inclined over the right eye. The guy wearing a blue sash and the typical curved sabre is an officer.

Bersaglieri were established as light infantry, basing their training on fast movements, sharp shooting, physical fitness and aggressiveness. They can be compared to the British "grasshoppers" with the main difference that bersaglieri are trained to run long distances while "the Rifles" marched "at the double".
They became soon the most recognizable element of the Kingdom of Sardinia army during the 4 Independence Wars (1848 - 1918).
Then, after 1WW, with the increasing motorization of armies, they were shifted to the role of infantry dedicated to the armour, motorized and cavalry division and that's why they are so frequently depicted in North Africa pictures. They are still in that role today, being the infantry element of the "heavy" Brigades of the Italian Army.
One of their mottos is "Faster than thought" and you can easily imagine as this can be used by the rest of the Army to mock them.

