Greater Rhea. Photo: Jacobia Dahm

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Inside Germany’s Giant, Hungry, Flightless-Bird Problem

Greater Rheas, native to South America, are thriving in northern Europe—and coming into conflict with farmers whose crops they eat.

On a cool morning last November, I brought my rental car to a sudden halt along a rural German road. My passenger, photographer Jacobia Dahm, had spotted a large bird in an adjacent field. Excited, and a little nervous, we left the car. Our boots sank into the muddy ground as we walked cautiously through the low morning mist toward the creature. The suspense built with each squelching step. Finally, at 10 feet away, the narrow silhouette came into focus. Only then did we realize: We hadn’t been stalking a bird at all. It wasn’t even an animal. It was a chest-high wooden post.

Though embarrassing, the mistake wasn’t altogether ridiculous. We were, after all, on our way to join a biannual survey of Greater Rheas—flightless South American birds that have taken up residence here, in northeast Germany, thousands of miles and an ocean away from their native land. Close relatives of ostriches and Emus, the lanky ratites stand up to five feet tall and weigh around 50 pounds. Between their considerable stature, gangly legs, and tawny coat, anyone might mistake a post for a rhea at a distance (or so I told myself).

The rhea’s unlikely appearance in the wild in this corner of the world began two decades ago, when seven birds escaped from their enclosure on a private property. Eventually, the escapees settled in the state of Mecklenburg-Western Pomerania, primarily inhabiting the meadows, marshes, and cultivated fields of the 120-square-mile Schaalsee UNESCO Biosphere Reserve. The rheas thrived, and their numbers quickly climbed to dozens, and then hundreds.

The massive birds gained a foothold at a time when Europeans are wrestling with rising human-wildlife conflicts as megafauna rebound on the landscape, from resurging wolf populations to a new free-roaming bison herd. Like those animals, the rheas of Germany have become a matter of great interest and contention. Some see them as a welcome addition—a boon for conservation of a bird threatened elsewhere. Others argue that rheas are yet another destructive, human-introduced mistake, like the Burmese pythons that have overrun the Everglades or the European rabbits that have eaten their way across Australia, wreaking havoc on crops and spurring the decline of native plants and animals. As the rhea population has increased, so have troubles with local farmers, whose crops have become a staple in the ratites’ diet, as well as concerns that they could become an ecological burden.

Yet no one has a good grasp on the birds’ wider impact in Mecklenburg-Western Pomerania, a question that the scientists and conservationists of the Nandu Monitoring Working Group hope to answer. (In Germany, as in South America, rheas are often referred to by their other name: nandus.) Twice a year, the group organizes a crew of volunteers who tally as many rheas as possible across the birds’ known range; the fall count takes stock of the recent breeding season’s success, while the spring survey gauges the birds’ survival over the winter. The surveys, along with the group’s studies on the birds’ effect on local flora and fauna, are key to documenting and forecasting the birds’ potential negative impacts.

Arne Korthals, an environmental consultant and head of the Nandu Monitoring Working Group. Photo: Jacobia Dahm

After recovering from our run-in with the wooden post, Dahm and I joined nearly 30 people dressed in hardy clothes and tall rubber boots in a parking lot in the tidy town of Schlagsdorf for the fall survey. Arne Korthals, an environmental consultant and head of the working group, divvied us up into eight search teams and debriefed us on our task. The participants, which included farmers, scientists, and reserve staff, held different opinions on the new natives. But they were all invested in the fate of these striking birds that have made themselves at home in their adopted country, even as their future here remains uncertain. 

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ith their long legs, Greater Rheas can work into a sprint of up to 37 miles per hour. In their native pampas and open woodlands of Argentina, Brazil, Bolivia, Paraguay, and Uruguay, this speed is essential for survival, allowing them to evade pumas and other predators. Their breeding behavior also gives them an edge. Each male attracts multiple mates with his elaborate, wing-flourishing courtship dance. The females he woos deposit several eggs into his nest before they move on to find more partners. The male often incubates more than 20 eggs at once, and after they’ve hatched, shows his fledglings the ropes, including teaching the young omnivores how to feed themselves. In South America, the birds have a varied diet of fruits, plants, seeds, insects, lizards, birds, small game and, more recently, crops, due to the spike in agricultural development.

While farms may offer some sustenance, the transformation of the wild lands that rheas depend on has caused their numbers to decrease. Compounding the decline is the long-standing tradition of hunting the birds for their skin and meat. Restrictions on hunting and trade exist but aren’t strictly enforced. Due to these downward trends, the International Union for the Conservation of Nature has listed the Greater Rhea as near-threatened since 1988.

The dwindling number of rheas in South America and the growing population in Germany makes for a strange dichotomy. Joaquín Navarro, a biologist and co-head of the Nandu Project at Argentina’s National University of Córdoba, recalls a visit to Schlagsdorf to consult on rhea management. He found it odd having to adjust his perception of the bird from a species in trouble to a potential pest. It was also wild to see how emboldened the German rheas were, compared to their timid counterparts in South America, he says.

In the early 2000s the new, lanky interlopers roaming across the German countryside were an amusing spectacle, drawing local and national news coverage and curious tourists. With no natural predators, the population expanded. (Car collisions and nest predation by wild boars, foxes, sea eagles, and, researchers suspect, poachers, kill the occasional bird, but the impact of these factors is minimal.)

Locally, amusement with the birds waned as the ever-increasing number of hungry mouths and powerful feet began harming crops. Most of the renegade rheas have made their home in the biosphere reserve, about half of which private landowners farm. Many cultivate rapeseed: a tall, flowering plant used primarily to make canola oil and biofuel. Rheas have developed a taste for the nutritious leaves of young rapeseed, and their appetites can cause considerable damage. In one extreme case, a farmer lost 50 percent of his yield on fields trampled by nandus two years in a row. “During the first years, people—farmers and politicians—found the rheas funny and interesting,” says Korthals. “With the increase in population, the damage on the agriculture, on rapeseed especially, resulted, and the farmers got angry.” They called for compensation for their lost crops, and for a reduction in the rhea population.

Funds to cover such losses, however, have been tricky to come by. Reinhold Jahnke, a long-time farmer in the area, describes watching flocks of dozens trample his fields, devouring his painstakingly cultivated rapeseed crop: “It’s not fun.” Jahnke has applied for compensation for lost crops, but he’s found the process time-consuming and has learned that funds are limited; he’s received roughly half of the amount he requested. Petra Böttcher, head of the Northwest Mecklenburg District Farmers Association, recognizes the international status of the birds and the difficulty of the situation. But she’s worried about what the growth of the rhea population means for the economic health of local agriculture. “If the public likes the fact that these animals live here,” she says, “then one has to be prepared to pay compensation.”

Even more befuddling is what to do about the birds themselves. In accordance with the German Federal Nature Conservation Act, a new species that survives and breeds successfully in the wild for several generations is considered native. As such, it’s awarded the same protections as any other native species, like the White Stork or gray wolf, making it illegal to catch, hunt, or kill rheas, or to damage or alter their habitat. Additionally, Jahnke and others say they don’t want to eliminate the birds altogether: they’re just looking for a balanced solution. “There must be a way to preserve the population and reduce the damage, so that it is bearable, and we can live with it.”

Greater Rhea footprint. Photo: Jacobia Dahm

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arly on, farmers focused on deterrents to prevent rheas from causing damages in the first place. Their efforts were, in accordance with regulations, non-lethal: electric fences, loud noises, offensive-smelling manure. Nothing worked. The birds would retreat for a bit, and then return to munch away once again. Farmers and biosphere reserve managers were at a loss. Culling or hunting the birds remained out of the question; legally, their hands were tied.

By 2015, however, things had started to shift. The rhea’s protected status was called into question amid regional farmers’ complaints about crop losses and ongoing research by the working group to determine the birds’ impact on the local biome. In April of that year the federal government deemed the Greater Rhea “potentially invasive” when it added the species to the gray list of the German Federal Agency for Nature Conservation. Though the decision didn’t affect the protections afforded to the rhea, it did mark the beginning of more aggressive efforts to keep rheas in check.

In 2017, when 244 rheas roamed free, Mecklenburg-Western Pomerania’s Ministry of Agriculture and the Environment approved the farmers association’s application to manipulate the birds’ eggs to suppress reproduction. Individuals named on the permit could drill freshly laid eggs in order to prevent maturation or apply paraffin, a colorless, waxy substance, to eggs, thereby depriving the embryos of oxygen. In 2018 farmers and biosphere reserve employees drilled or applied paraffin to 190 eggs, out of the 238 they found. Despite these efforts, that fall the population reached an all-time high of 566 individuals. (“Farmers powerless against the Nandus,” read a December 2018 Agriculture Today headline.)

With pressure from farmers increasing, and likely bolstered by the birds’ gray-list status as a potentially invasive species, the state government for the first time allowed lethal action to be taken against adult rheas. In spring 2019 they issued permits to shoot 10 rhea cocks to two farmers, who killed 17 birds total. (What to do with the carcasses was left to their discretion.) This past April the state went even further, making it legal to hunt rheas. Now, just as with deer or wild boar, hunters with a valid hunting permit can shoot rheas during the official hunting seasons: year-round for rhea chicks and yearlings, and November 1‑March 31 for adult birds.

Amid these efforts to reduce human-rhea conflict, Korthals and other scientists have been trying to answer the question that’s at the root of the species’ existence in Germany: Do rheas adversely affect the local environment? So far, research has shown that the ratites have little to no impact on native flora, or on other ground birds. Korthals, with researchers from the reserve as well as the Leibnitz Institute for Zoo and Wildlife Research, is now working on the final unknown: studying whether the birds harm native insect populations in the biosphere reserve. Korthals also plans to launch an investigation next year into whether the rhea’s grazing habits might, in fact, benefit vegetation, as the birds are known to consume harmful insects.

Once the work is completed, Korthals says, authorities will have definitive evidence to determine whether or not nandus have a negative ecological impact to the point where they should be considered invasive. Depending on the ruling, the birds might regain the full protection of a native species. Or, if designated invasive, rheas might be even more aggressively controlled.

While humans debate and fret over the rheas’ circumstance, the birds themselves continue to roam and reproduce.

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oon after starting our survey, our group—three biosphere reserve employees, Dahm, and myself—stopped alongside a rapeseed field. There they were, at last, in the gilded light of a northern winter. A flock of more than 50 rheas—real ones. Heads dipping to eat, wings adjusting, bowels emptying, they were just as impressive as I had hoped, and I was struck by how anachronistic, how dinosaur-like, they looked.

The vehicle itself didn’t seem to disturb them, but as we slid open the van door, they began to creep slowly away, not quite looking at us, as if they were sauntering off on their own terms. As we slowly exited, a few birds began to run. Then more joined, and more, until only a few brave or lazy individuals remained. They, too, eventually followed, and the flock gathered once again, half a mile away—slim figures against a pale blue sky on the ridge of a low hill.

Biosphere reserve employees take part in the fall nandu survey. Photo: Jacobia Dahm

As the day wore on, we methodically covered several square miles. For each individual we saw, we noted distinct markings on a simple, blank rhea diagram, shading in unique gray or black swatches on the neck or the wings to ensure each bird was only counted once. A few hours in, the strangeness of the rheas began to wear off. Watching them commingle in a field with geese and swans, I was struck by the illusion that we were the ones out of place. That we had crossed into a land of giant birds.

After our group later disbanded, Dahm and I walked along a muddy tire track far out into another rapeseed field, following a flock that contained a bright white bird: an albino rhea. The birds fled as they had before, slowly at first, and then at a trot until they were out of sight. When I looked down, however, evidence of the birds’ presence remained. Trails of raptor-like footprints and puddles of droppings extended to my left and right. I was standing on a nandu highway.

During that fall count, the eight teams had tallied a total of 456 rheas. This past spring the surveyors counted far fewer birds: 247. It’s possible that the egg manipulation and hunting permits have taken a toll, reducing the rheas’ ranks. But many are skeptical that so many birds have disappeared and wonder if, instead, the low count is a reflection of the birds’ adapting. In an interview with a local newspaper this spring, Böttcher theorized that recent culling efforts have made the birds shier and warier of humans. Others, meanwhile, hypothesize that after two decades of hunkering down on the biosphere reserve, the birds are branching out farther into the German countryside, extending the highways they travel, and possibly establishing new rhea territory.

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