Germans are getting used to a new kind of immigrant. In 1998, a pack of wolves crossed the shallow Neisse River on the Polish-German border. In the empty landscape of Eastern Saxony, speckled with abandoned strip mines and declining villages, the wolves found plenty of deer and rarely encountered humans. They multiplied so quickly that a second pack has since split off, colonizing a second-growth pine forest 30 kilometers further west. Soon, says local wildlife biologist Gesa Kluth, a third pack will likely form, possibly heading northward in the direction of Berlin.

Wolves returning to the heart of Europe? A hundred years ago, a burgeoning, land-hungry population killed off the last of Germany's wolves. Today, it's the local humans whose numbers are under threat. Wolf-country villages like Boxberg and Weisswasser are emptying out, thanks to the region's ultralow birthrate and continued rural flight. Nearby Hoyerswerda is Germany's fastest-shrinking town, losing 25,000 of its 70,000 residents in the last 15 years.

Such numbers are a harbinger of the future. Home to 22 of the world's 25 lowest-birthrate countries, Europe will lose 41 million people by 2030 even with continued immigration, according to the latest U.N. Population Division report. The biggest decline will hit rural Europe. As Italians, Spaniards, Germans and others produce barely half the children needed to maintain the status quo--and rural flight continues to suck people into Europe's suburbs and cities--the countryside will lose close to a third of its population, say both the United Nations and the EU. "It's a triple time bomb," says University of Lisbon demographer Nuno da Costa. "Too few children, too many old people and too many of the remaining young people still leaving the village."

The implications of this transformation touch on everything from tourism to retirement locales to government conservation and agricultural policies. Our postcard view of Europe, after all, is of a continent where every scrap of land has long been farmed, fenced off and settled, where every tree has been measured, counted and named. But the continent of the future may look rather different. "Big parts of Europe will renaturalize," says Reiner Klingholz, head of the Berlin Institute for Population Development. Bears are back in Austria. In Swiss alpine valleys, farms have been receding and forests are growing back in. In parts of France and Germany, wildcats and ospreys have re-established their range.

This sounds like an eco-environmentalist's dream, inspiring loose talk of a Europe Pastoral--the return of wide-open spaces and primeval wilderness to a densely settled landscape. Yet the truth is more varied, and interesting. While many rural regions of Europe will empty out, others will experience something of a renaissance. Already, attractive areas within striking distance of prosperous cities are seeing robust revivals, driven by urban flight and a rising influx of childless retirees. From Provence to Piedmont, Kent to the Costa del Sol, ex-urbanites are snapping up vacation homes, hobby vineyards and horse farms.

Contrast that with less-favored areas--from the Spanish interior across the Alps to Scandinavia and Eastern Europe. These face dying villages, abandoned farmsteads and changes in the land not seen for generations. Both types of regions will have to cope with a steeply aging population and their accompanying health and service needs, says Gunnar Malmberg, a rural geographer at Sweden's Umea University. "Rural Europe is the laboratory for demographic change."

Visit the Greek village of Prastos for an extreme glimpse of what Malmberg might mean. An ancient hill town in the eastern Peloponnese, Prastos once had 1,000 residents, most of them working the land. Now only a dozen are left, most in their 60s and 70s. With no children, the school has been closed since 1988. Sunday church bells no longer ring. "The old people here will die," says visiting ex-resident Petros Litrivis, 60. "Everything will be abandoned." Without farmers to tend the fields, rain has washed away the once fertile soil. Of the 50,000 goats that once grazed the hills, only a fraction remain. As in much of Greece, land that has been orchards and pasture for some 2,000 years is now covered with a parched scrub that, in the summer, frequently catches fire.

Rural depopulation is, of course, not new. Thousands of villages like Prastos dot Europe, the result of a century or more of emigration, industrialization and agricultural mechanization. "But this time it's different because never has the rural birthrate been so low," demographer Costa says. In the past, for example, a farmer could usually find at least one of his offspring to take over the land. Today, chances are he has but a single son or daughter, usually working in the city and rarely willing to return. In Italy, more than 60 percent of the country's 2.6 million farmers are at least 65 years old. Once they die out, many of their farms will join the 6 million hectares (one third of Italian farmland) that has already been abandoned.

Rising economic pressures will amplify the trend. One third of Europe's farmland is marginal, from the cold northern plains to the parched Mediterranean hills. Most of these farmers subsist on EU subsidies, since it's cheaper to import food from abroad. Already, the EU is trying to limit costly overproduction by paying farmers not to farm. "Without subsidies, some of the most scenic European landscapes would not survive," says Jan-Erik Petersen, a landscape biologist at the European Environmental Agency in Copenhagen. Take the Austrian or Swiss Alps. Defined for centuries by orchards, cows and high mountain pastures, those steep valleys are labor-intensive to farm, with subsidies paying up to 90 percent of the cost. The Austrians and Swiss pay up so that the postcard-perfect scenes can continue to exist. Across the border in France and Italy, subsidies have been reduced for mountain-farming. Since then, all across the southern Alps, villages have emptied out and forests have grown back in.

This isn't necessarily the environmentalist's dream it might seem. The scrub brush and forest that grows on abandoned land might be good for deer and wolves, but is vastly less species-rich than traditional farming, with its pastures, ponds and hedges. "Once shrubs cover everything, you lose the meadow habitat. All the flowers, herbs, birds and butterflies disappear," says the EEA's Petersen. "A new forest doesn't get diverse until it's a couple of hundred years old." An odd alliance of farmers and environmentalists have joined to put pressure on the EU to "keep the landscape open," as World Wildlife Fund spokeswoman Catherine Bett calls it. Keeping biodiversity up by preventing the land from going wild is one of the reasons the EU pays farmers to mow fallow land once a year. France and Germany subsidize sheep herds whose grazing keeps scenic heaths from growing in. Outside the range of these subsidies--in Bulgaria, Romania or Ukraine--big tracts of land are returning to the wild.

For governments, the challenge has been to develop policies that slow the demographic decline or attract new residents. In some places, such as Britain and France, large parts of the countryside are reviving more or less on their own as an increasingly wealthy urban middle class in search of second homes recolonizes villages and farms. In southern England, farmland prices have soared, helped along by burned-out investment bankers become hobby farmers, raising organic produce or rare breeds of pigs (box).

Riding this wave, villages like Santo Stefano di Sessanio in central Italy--down from 1,700 in the early 20th century to 124 mostly elderly people today--are counting on tourism to revive their town. A Swedish investor has bought an entire section of the village and is turning the conjoining medieval buildings into a complex of hostels for tourists and hikers headed for the nearby Abruzzo mountain chain. In Tuscany, an Italian count has taken the entire empty village of Gargonza and turned it into a luxury wellness spa. "The nice villages will be turned into hotels, and the ugly villages will be housing for hotel employees," imagines Carlo Altomonte, an economist at Milan's Bocconi University.

That may be a pipe dream. Once the baby boomers start dying out around 2020, population will start to decline so sharply in many European countries that there simply won't be enough people for every town to reinvent itself as an ex-urbanite enclave or tourist resort. It's similarly unclear how long current government policies can stave off the inevitable. In northern Sweden, a vast land of thick forests and small rural settlements, three decades of massive spending haven't halted the decline. "In Sweden we now talk about civilized depopulation," says Mats Johansson of the Royal Technical Institute in Stockholm. "We just have to make sure that the old people we leave behind are taken care of."

Eastern Germany is a case study unto itself. Taxpayers have sunk more than 100 billion euro into rural areas, without even a blip in the speed of decline. The countryside is full of subsidized white elephants, from a bankrupt zeppelin factory in Brandenburg to a never-used Formula 1 speedway close to that part of nowhere in which the wolves now roam. Oblivious to the demographics, hundreds of rural communities built vastly oversize water networks and sewage systems, each certain of drawing new businesses and residents. In nine cases out of 10, a dwindling number of villagers now face sharply rising costs. Worse, in some villages there are now too few people flushing for the sewage to properly flow, requiring costly investments to redimension the pipes. Shrinking, they've found, can be an expensive proposition indeed.

Some communities are turning by necessity into laboratories of innovation. In the Swiss canton of Graubunden, where the number of children has sharply dropped, school authorities in the 1980s reintroduced one-room schoolhouses in hundreds of hamlets. "Now we're entering the next phase," says Dany Bazzell of the Graubunden schools department. "There are so few children that not even the one-room schools will survive." In depopulating northern Sweden, Umea University is pushing online learning, giving students an incentive to stay in their village instead of moving away to college, from where they rarely return. Even the French have relaxed their famously strict labor rules for small-town residents, allowing people to combine part-time farm work with civil-sector jobs (such as teaching).

The biggest challenge, however, is finding creative ways to keep up services for the rising proportion of seniors. In the countryside, longer distances can make that tough. When the Austrian village of Klaus, thinly spread over the Alpine foothills, decided it could not afford a regular public bus, the community set up the Dorfmobil, a public taxi-on-demand. It now serves mainly old people without cars or relatives left to drive them. In thinly populated Lapland, an area of 80,000 square kilometers where doctors are few and far between, tech-savvy Finns are meeting the rising demand for specialized health care with Tel Lappi, a service that uses videoconferencing and the Internet for remote medical exams.

Another pioneer is the Spanish village of Aguaviva, whose residents have formed what may be Europe's first grass-roots, small-town movement to welcome foreign immigrants. In Spain's vast interior, one of Europe's most quickly depopulating regions, many villages are already abandoned, while 90 surviving ones, including Aguaviva, have banded together as the Spanish Association of Towns Against Depopulation. In 2000, Mayor Luis Bricio began offering free airfare and housing for foreign families to settle in Aguaviva, a mud-brown town of about 720 on the dry plain in Teruel province. Now, Aguaviva has 130 mostly Argentine and Romanian immigrants, coddled by locals who are grateful that they came. After closing all but the last classroom in the 1990s, Aguaviva has hired another teacher and again boasts 92 school-age kids. "Aguaviva was going to disappear from the map," Bricio says. "Immigration was our only solution."

On a continent with an often troubled relationship to migrants, such bracing realism is an astonishing step. For the most part, though, it's no solution. Like Europeans themselves, most foreign immigrants continue to prefer cities, where many of them already live. And within Europe, migration only exports the problem. Western Europeans look toward Eastern Europe as a fallback source for easy-to-integrate migrants, for instance, yet these countries have ultralow birthrates of their own. Ukraine and Bulgaria will see their populations drop by a third by midcentury. With the EU alone needing about 1.6 million immigrants a year above its current level to keep the working-age population stable between now and 2050, a much more likely source of migrants would be Europe's Muslim neighbors, whose young populations are set to almost double in that same time. But that's a hot-button issue few are as yet willing to address.

Other nettlesome issues are still open, as well. Increasingly, worried European governments are crafting natalist policies to nudge couples to have more children, from offering better child care to monthly stipends keyed to family size. They hope to copy France, which first implemented such policies in the 1930s and remains one of Europe's very few growing countries. Trouble is, these measures might raise the birthrate slightly, but across most of the aging continent there are just too few potential parents around today.

As for the land itself, right now there's a trend in many areas toward abandoning less productive land, which is sometimes reforested, sometimes left to go wild. In the American West, this might have been part of the natural cycle: people move on and the wilderness grows back. "But for thousands of years we Europeans are used to having fields and orchards and pastures around our towns," says Michel Revaz, a Swiss Alpine biologist. "It's part of our genes." The landscape, he says, is glued to the European identity, reflecting what the Germans call "Kulturlandschaft"--a landscape shaped by centuries of human care. Today's unprecedented population decline, amplified by the shifting economics of farming, puts the future of many of those Kulturlandschaften in doubt, just as pressure to cut the subsidies that fund them rises. Many Europeans are reluctant to just let nature do its thing. "We still cry when the woods close in," Revaz says. Unless, of course, you're a fan of the wolves.