Wild mammals on Earth are in big trouble. In the cold light of ecological arithmetic, they barely register anymore.

Of all the mammalian biomass on the planet, just 4% is still wild. The rest — us and our livestock — dominate the land in both weight and numbers. It didn’t use to be like this, of course. All of nature was wild; then most of it; then some; now, almost none. For centuries, the wild things were pushed to the brink, hounded from forests, slaughtered on sight, and reduced to relics of memory and myth. In Europe, where most cities industrialized and expanded quickly, mammals seemed destined for ghosthood.

And yet, quietly, almost astonishingly, a reversal is underway.

It’s not that all is well and things are back to pre-human levels. But across the fields and forests, in several countries, wolves now howl again. Beavers rebuild dams their ancestors last touched a century ago. Bison, once gone from the wild, are roaming the Carpathians once again. Mammal populations long thought doomed are rising — not everywhere, and not without friction, but enough to tell a stunning story of conservation and resilience.

So, what’s going on?

A silent success story

Humans are still wrecking the planet. We’re still causing climate change and pollution, still expanding into habitats, and still shaping the world entirely based on our needs. It’s easy to miss the bright spots. But Europe’s mammal resurgence is no mirage. It’s backed by decades of monitoring, satellite data, fieldwork, and historical records.

A report by Rewilding Europe, compiled with the Zoological Society of London and BirdLife International, identified strong or moderate comebacks in many of the 24 mammal species tracked. These aren’t marginal upticks, they’re exponential rebounds.

The Eurasian beaver, once hunted to near oblivion, has rebounded by over 16,000% in monitored populations since the 1960s. Their dams now trickle through landscapes they haven’t touched in living memory. The grey wolf has clawed its way back from just 12,000 individuals in 2012 to over 21,500 by 2022 across Europe. The brown bear’s Spanish populations are expanding genetically and demographically for the first time in decades.

These returns aren’t random. They are, in fact, instructive. We just needed to do one thing: stop the activities that were killing mammals off in the first place.

Policy made a huge difference

So, what turned the tide?

One answer is laws — powerful, multinational ones. The EU Habitats and Birds Directives created sweeping protections and offered a framework for all EU countries to protect valuable and threatened species. The creation of a network called Natura 2000 also made a big difference. The network consists of over 27,000 protected areas. Large carnivores such as wolves, bears, and lynx now enjoy strict safeguards. National hunting bans and quotas, such as those introduced in Sweden for brown bears, stopped the bleeding.

Another answer is less intentional and less optimistic: abandonment.

As agriculture declined in marginal areas and people migrated to cities, forests quietly regrew. This process, dubbed “passive rewilding,” became an accidental gift to nature. In these re-emerging wild patches, mammals found breathing space.

All this has led to a surprising situation: Europe today may harbor more mammal species than it did 8,000 years ago. It’s not more individual animals in total, but more biodiversity than at the dawn of civilization is definitely unexpected. A study led by the University of York compared present-day diversity with the post-Ice Age baseline and found a net gain in species richness across much of the continent, despite extinctions like the auroch and European wild ass.

The fine print

This is not to say Europe has returned to some primordial Eden.

Deforestation is still a major problem, while urbanization and climate change continue to stress out wild populations. Not all species now in Europe are native; some are invasive and actually cause problems. Then, some populations remain tiny and fragmented. Others, like the Eurasian otter, are recovering unevenly and may be stalling in some regions. And crucially, number gains don’t erase genetic bottlenecks.

The European bison, despite its resurgence, remains genetically impoverished. All living individuals descend from just 12 ancestors, leaving the species vulnerable to disease, infertility, and climate stress. New genomic tools like SNP panels are helping conservationists monitor and manage this fragile legacy.

Not everyone is thrilled that there are more wild animals in Europe, either.

Livestock losses to wolves and bears stoke resentment, particularly in rural communities. An estimated 56,000 domestic animals are killed by wolves annually in the EU, costing €17 million in compensation. Ungulates like deer and boars damage crops, reforesting efforts, and trigger car collisions. Otters threaten fish farms; beavers flood infrastructure.

There are tensions, for sure. But there are also solutions.

Some governments and NGOs are moving beyond reactive payouts to more proactive prevention. In Spain and Italy, livestock owners receive support to install electric fencing or deploy livestock-guarding dogs — methods proven to reduce depredation. Sweden’s innovative wolverine scheme ties financial compensation directly to reproduction, rewarding herders for every surviving cub, turning conservation into collaboration. Across Europe, stakeholder platforms have emerged to give local communities a say in how large carnivores are managed, building trust where mistrust once reigned.

Things are far from fine and dandy. But the mammal apocalypse in Europe seems to have been averted for now.

Where do we go from here

Fragmented habitats, climate change, and poaching continue to threaten Europe’s mammals. Many protected areas remain paper parks — protected in name but not always in practice. And even the most successful programs can falter without public support.

What would success really look like?

Success means species not just surviving, but shaping ecosystems again. It means rural livelihoods and wild animals coexisting without resentment, sustainably. It means policies that evolve with populations, but don’t cave to political backlash. It means vigilance, humility, and science.

Europe’s mammal recovery is a rare bright thread in the tangle of biodiversity loss. It shows that given the right conditions — legal, social, and ecological — life can push back against extinction. The question now is whether we have the foresight to keep those conditions alive.