STORY: Meet the staff at one vineyard in South Africa's winemaking town Stellenbosch.
This army of around 500 Indian runner ducks has a taste for snails.
And that's useful if you want to keep your vines pest-free.
"We call them the soldiers of the vineyards."
Corius Visser, managing director at the Vergenoegd Low Wine Estate, says the ducks help the vineyard steer clear of pesticides and synthetic fertilizers.
And this breed is especially suited to the job.
“They don’t waddle like normal ducks, they walk. They’ve got an upright posture and their long necks actually help them to eat the snails within the vineyards itself. When it’s up there, between the leaves, they can reach that, and they can eat them there."
As well as natural pest control, the ducks also provide entertainment for tourists like Merle Holdsworth.
“It's amazing how they behave themselves, walk in a row, and it's like, they're in the army, or whatever.”
Visser says Indian runner ducks are "very trainable" and soon get into their routine.
They know their way, he says, back to the paddocks each evening where they get additional bird food.
And after a day of feasting in the vineyard there is one more benefit.
Their nutrient-rich manure makes great fertilizer - just another way for the estate to be as sustainable as possible.