Earlier this year, thousands worldwide were miffed to learn that social media rumors of a locust-eating army of ducks, purportedly set to protect Pakistan from pests, were false—but not all bird-based cavalries are fake news.

For nearly four decades, South Africa’s Vergenoegd Löw the Wine Estate has been deploying a daily parade of waterfowl more than 1,200 strong to keep their snail and insect population in check, Ulrike Lemmin-Woolfrey reports for Atlas Obscura.

The approach helps remove snails and bugs from the establishment, which opened in 1696, without the need for harsh chemicals that could damage the environment. “We try to keep a pesticide-free farm by using the ducks,” Denzil Matthys, Vergenoegd’s duck caretaker, told NPR’s Sarah Birnbaum in 2016. “They help us not to use poison on the farm.”

Each morning, around 7 a.m., the vineyard’s horde of Indian runner ducks—a fast-jogging but flightless breed of domestic duck—awakens from their slumber. By about 10:30 a.m., they’ve crossed through the gate separating their residence from the vineyard and start scarfing down pests galore. Situated near the ocean, Vergenoegd’s plot of land is plagued by an abundance of white dune snails, which love to feast on the buds sprouting off grape vines in spring. Picked clean, the plants would no longer be able to produce fruits necessary for the vineyard’s signature shiraz, merlot, malbec and cabernet sauvignon wines, among others.

Aided by their agile bodies, long necks and sharp, quick beaks, the birds can pluck snails from vines and trunks, wriggling between rows of plants with an indefatigable spirit. “The Indian runner duck is the best worker in the vineyard,” Matthys told NPR.

Should any troublesome six-legged creatures show up at the vineyard, the ducks will generally snap those up, too, feasting even on mosquito larvae. Gavin Moyes, the estate’s tasting room manager, notes that the birds also bring their benefits full circle: Their nutrient-rich dung “helps our vines grow,” he tells Atlas Obscura.

This unusual strategy has precedent in Bali, where ducks are regularly dispatched to fertilize rice paddies before seeds are planted, and in China, where officials once released thousands of ducks and chickens to combat a swarm of locusts laying waste to agricultural plots. According to some reports, ducks are hungrier than their chicken coworkers, and are capable of consuming up to 200 locusts a day.

At Vergenoegd, which started using ducks in 1984, feathered workers enjoy certain privileges. To keep the birds’ concentration focused on the job at hand, the vineyard’s owners maintain a small but fierce team of geese, who guard their feathered comrades from mongoose, owls and other predators.

The ducks’ day ends around 4 p.m., when human herders wave them back into formation with flags, according to NPR. Obliging as ever, the birds will shuffle in an orderly fashion back to their home: a series of small colonies, scattered around the estate’s lake.

In an interview with Atlas Obscura, Moyes is careful to mention that the ducks are not turned into a menu item when they retire: “That would be like eating your colleagues,” he says.

When their appetite and physical stamina begin to wane, the ducks lounge on the lake’s island for the rest of their days.