Large herbivores are ecosystem engineers. Their grazing, browsing, and movement patterns shape vegetation structure, nutrient cycling, and habitat diversity. The rewilding of large herbivores — returning them to landscapes from which they have been extirpated — is one of the most ecologically ambitious and welfare-complex conservation strategies of our time. In 2025, dozens of projects worldwide are attempting to restore these ancient ecological relationships, raising profound questions about animal welfare alongside ecological restoration.
Large herbivores play disproportionate roles in shaping ecosystems relative to their numbers. Through selective grazing and browsing, they prevent vegetation from reaching monoculture states, creating structural diversity that benefits hundreds of other species. Their wallowing creates wetland habitats; their dung fertilizes soils and feeds invertebrates; their trails become pathways used by many species; their carcasses feed scavengers and enrich soils.
The loss of large herbivores — through hunting, habitat loss, and competition with livestock — has contributed to what ecologists call "trophic downgrading," a simplification of ecosystems that ripples through food webs. Rewilding projects seek to reverse this by reintroducing functional equivalents of lost megafauna.
Once extinct in the wild, European bison now number over 7,000 following decades of captive breeding and reintroduction. Poland's Białowieża Forest hosts the largest free-roaming population. New reintroductions are underway in UK, Netherlands, Romania, and the Caucasus. The species demonstrates rewilding success but welfare monitoring remains essential during establishment phases.
Przewalski's horse — the only truly wild horse species — has been reintroduced in Mongolia, Kazakhstan, China, and France. Feral horse populations in North America (mustangs) present complex welfare and ecological debates. Welfare during reintroduction includes managing band social structure, preventing inbreeding, and ensuring adequate forage.
The aurochs — ancestor of domestic cattle — went extinct in 1627. Back-breeding programs (Tauros Project, Heck cattle, Taurus project) seek to recreate functional ecological equivalents. Welfare concerns center on selection for robustness and wildness while maintaining manageable temperament, and ensuring reintroduced animals can survive independently.
Wild boar are natural ecosystem engineers through rooting behavior, which creates soil disturbance that benefits plant diversity. Across Europe, expanding wild boar populations are rewilding many landscapes organically. Welfare concerns arise around population management conflicts and disease (ASF), as well as human-wildlife conflict.
Expanding moose/elk populations across Scandinavia and parts of Central Europe are naturally rewilding landscapes. Reintroduction programs in areas where they were extirpated are growing. Their impact on forest structure — browsing young trees — creates heterogeneous habitat. Welfare considerations include vehicle collisions and hunting management.
African elephants, Cape buffalo, hippos, and rhinos are being actively rewilded in reserves across southern and eastern Africa. Translocation of entire family groups for elephant welfare requires sophisticated logistics. The Malawi Wildlife Project and others have demonstrated successful large-scale herbivore rewilding.
Rewilding is not simply releasing animals — it involves complex welfare considerations throughout the process of capture, translocation, release, and establishment.
Capturing large wild herbivores — through chemical immobilization, boma (enclosure) trapping, or helicopter herding — causes significant acute stress. Capture myopathy, a potentially fatal syndrome caused by extreme exertion and stress, is a major risk. Modern protocols emphasize minimizing capture time, monitoring vital signs, providing shade and water, and using appropriate reversal agents for anesthesia.
Welfare Risk: Translocation Mortality — Large herbivore translocations carry mortality risk of 1-15% depending on species, conditions, and transport distance. This is a genuine welfare cost that must be weighed against long-term population and ecological benefits. Best practices continue to improve outcomes, but zero-risk translocation remains impossible.
Releasing animals into unsuitable habitat causes suffering and mortality. Thorough ecological assessment before rewilding projects begins is essential. Habitat must provide adequate food, water, shelter, and space. Disease screening of resident and translocated animals prevents outbreak risk. Preliminary "soft release" — allowing adaptation in enclosed areas before full release — can improve outcomes.
Where predators are absent, large herbivores may overpopulate, leading to habitat degradation and eventual starvation. Managing this welfare challenge requires either predator reintroduction (itself welfare-complex) or active population management. Population management through contraception, culling, or translocation must be conducted with welfare protocols.
Many large herbivores have complex social structures. Bison have dominance hierarchies; horses live in family bands; elephants have matriarchal family groups with deep social bonds. Disrupting these structures during rewilding — for example, separating family members — causes significant behavioral and welfare impacts. Best practice involves maintaining social groups during translocation wherever possible.
The oldest and largest bison rewilding program has grown the European bison population from 12 individuals in 1927 to over 7,000 today. Annual monitoring assesses population health, genetic diversity, and individual welfare. Human-bison conflict management and forest management tensions (logging threats) remain ongoing challenges.
The American bison — once numbering 30-60 million before near-extermination — now has approximately 500,000 individuals, mostly in managed herds. Indigenous-led rewilding on Tribal lands represents the most ecologically ambitious restoration, with the InterTribal Buffalo Council managing large free-roaming herds. Welfare considerations include maintaining genetic diversity and managing human-bison interactions.
The Knepp rewilding project in West Sussex has transformed 3,500 acres of former farmland through introduction of longhorn cattle, Tamworth pigs, Exmoor ponies, and red and fallow deer as large herbivore proxies. Animal welfare is integral to Knepp's approach — animals are monitored for body condition, veterinary care is available, and minimal intervention philosophy is balanced with welfare obligations.
Attempting to recreate mammoth-steppe grassland ecosystem in Arctic Siberia, this project has introduced bison, horses, musk oxen, reindeer, and other large herbivores to compact permafrost-preserving snow. Extreme climate conditions create significant welfare challenges; animal monitoring in remote Arctic conditions is logistically demanding.
Multiple programs across Africa are rewilding large herbivores — elephants, rhinos, hippos, and others — into reserves. The black rhino particularly has benefited from intensive rewilding programs that have seen numbers grow from ~2,500 in 1995 to over 6,000 today, though still critically endangered.
Rewilding forces direct confrontation with the tension between conservation ethics (focused on population and ecosystem level) and animal welfare ethics (focused on individual animals). These perspectives sometimes conflict:
Population vs. Individual: Conservation may accept some individual animal suffering or mortality if it benefits population viability. Animal welfare ethics prioritize minimizing individual suffering. Rewilding requires explicitly negotiating this tension — establishing which individual welfare costs are justified by conservation benefits, and which are not.
A core rewilding philosophy advocates for minimal human intervention, allowing natural processes including predation, competition, and disease to shape populations. But this conflicts with welfare obligations when animals suffer from preventable causes. When should rewilded animals receive veterinary intervention? Most practitioners now advocate for a "safety net" approach — intervening for acute suffering, disease outbreaks, or invasive species threats, while allowing natural processes otherwise.
Large herbivores rewilded into human-dominated landscapes inevitably come into conflict with agriculture, infrastructure, and human safety. Bison breaking fences, elephants raiding crops, deer causing vehicle accidents — these conflicts have real welfare implications for both animals and humans.
Best-practice conflict management approaches include:
Effective welfare monitoring of rewilded large herbivores requires ongoing assessment of individual and population health. Techniques include:
The Convention on Biological Diversity's 30x30 target (protecting 30% of land and ocean by 2030) and the EU Nature Restoration Law create policy frameworks that could dramatically expand large herbivore rewilding. If implemented with genuine welfare integration — not treating animals purely as ecological tools — this represents transformative potential for both ecosystem restoration and animal welfare.
Emerging technological tools including precision GPS tracking, remote physiological monitoring, and AI-aided behavioral analysis will improve our ability to monitor and support rewilded herbivore populations. The field of compassionate conservation — explicitly integrating individual animal welfare into conservation decision-making — continues to mature, providing ethical frameworks for navigating the inevitable tensions.
Rewilding large herbivores represents one of conservation's most ambitious and ecologically promising strategies. Done well, with genuine welfare integration, it can restore ecological function while providing good lives to wild animals in genuinely wild conditions. Done poorly — treating animals as ecological pawns — it risks significant suffering. The best rewilding programs of 2025 demonstrate that ecological ambition and animal welfare are complementary rather than competing values, and that the return of these magnificent ecosystem engineers can be achieved with both ecological integrity and compassionate care.