Self-regulation of wildlife populations: Scientific evidence from Geneva, the National Park and international comparison

Self-regulation is not a theory: 50 years of Geneva and 110 years of the National Park prove that wild animals stabilise without recreational hunting.

The question of whether wild animal populations regulate themselves without recreational hunting is central to the legitimacy of Swiss hunting practice and is politically charged.

The recreational hunting lobby argues that without kills, the ecological balance would collapse. The counter-position, supported by long-term observations in the canton of Geneva, the Swiss National Park and international research, tells a different story: wildlife populations are regulated primarily by food availability, predators and habitat capacity, not by kill quotas. This dossier brings together the scientific evidence and honestly shows where researchers genuinely disagree.

What awaits you here

Canton of Geneva since 1974: 50 years of a long-term experiment in a densely populated canton with intact biodiversity and stable ungulate populations.
Swiss National Park since 1914: 110 years of a hunting ban, scientifically documented biodiversity and a nuanced analysis of the red deer problem of the 1980s.
Compensatory reproduction: why recreational hunting produces the very populations it claims to regulate. Evidence from wild boar, red deer, bear, puma and jackal.
Where researchers disagree: browsing damage, predators as a substitute for hunting, and the scalability of the Geneva model.
International comparative findings: from Luxembourg to Yellowstone to Słowiński National Park in Poland.
What must follow politically: concrete demands on the federal government, the cantons and research.
Argumentation guide: Answers to the six most common objections to the self-regulation thesis.
Quick links: to related dossiers and overviews of studies.

Canton of Geneva since 1974: Europe's longest-running field experiment

The canton of Geneva is the world's only long-term experiment in a hunting ban in a densely populated, economically intensively used area. On 19 May 1974, around two thirds of Geneva's population voted to abolish militia hunting. Since then, around a dozen cantonal environmental wardens, who share just under three full-time positions, have carried out all necessary wildlife interventions; the entire wildlife management costs around 1.2 million francs per year.

What the data show after more than fifty years is impressive. A long-term cantonal study documents a sharp increase in biodiversity since 1974. Despite its high population density, viticulture and international airport, Geneva is now considered one of the most biodiverse cantons in Switzerland. Lake Geneva and the Rhone have become waterbird reserves of international importance. The number of overwintering waterbirds rose spectacularly after the hunting ban, with no comparable trend in neighbouring cantons. The density of European hares stands at 17.7 animals per 100 hectares, far above the Swiss average. Ungulate populations are also stable, with around 100 red deer and 330 roe deer. Roe deer, red deer and wild boar, which were considered almost extinct in 1974, have re-established themselves.

Public acceptance is overwhelming. In 2004, almost 90 per cent of Geneva's population voted against reintroducing recreational hunting. In 2009, the cantonal parliament rejected a corresponding motion by 71 votes to 5.

The limits of the Geneva model

Even critically minded researchers must acknowledge that the Geneva model is not a model entirely without regulation. As wildlife populations grew, significant forest damage caused by ungulates was documented, which forced the creation of a forest-wildlife concept in accordance with FOEN implementation guidance. In response, wildlife fencing was reinforced and targeted culls of roe deer were carried out, overseen by professional game wardens.

The hunting-friendly magazine « Tierwelt » notes that “it is going so well that even the small canton cannot do without hunting”, and reports that the European hare population had to be kept in check. In 2007, around 60 animals were relocated to Valais and France. In addition, growing wildlife populations increased the risk of wildlife-vehicle collisions. Between 50 and 100 such incidents are reported each year.

The critical assessment is central: the Geneva model disproves the claim that hunting-free systems lead to collapse. At the same time, it demonstrates that professional interventions remain necessary — but carried out by trained game wardens rather than armed recreational hunters. The long-serving Geneva fauna inspector Gottlieb Dandliker (2001 to 2025) stated clearly that roe deer do not threaten the forest, and that in the predominant oak forests, little damage was recorded.

More on this: Geneva and the hunting ban and Hunting Fact Check

Swiss National Park since 1914: the oldest experiment

Since its founding in 1914, the Swiss National Park has been legally protected as a reserve in which nature remains free from all human intervention, including hunting. It is thus the oldest and strictest hunting-free area in Switzerland.

In 1914, botanists assumed that the former alpine pastures would quickly become overgrown. Research findings show the opposite. Species diversity rose from an average of 17 species per square metre in 1921 to 42 species per square metre in 2011. Red deer hinds keep the turf short through grazing, thereby promoting biodiversity. More recent studies show that the emergence of young trees is less influenced by browsing damage and instead depends more on site-specific and climatic conditions. At the current red deer density, forest regeneration is by no means being prevented. A study published in 2025 in «Ecology and Evolution» also showed how red deer contrastingly adapt their habitat choice inside and outside the national park — evidence of complex behavioural adaptations in hunting-free areas.

The red deer problem of the 1980s: a real crisis or political instrumentalisation?

This is where the greatest scientific controversy lies. After the national park was founded, red deer populations developed exponentially. In the 1980s, peaks of around 3,000 animals were reached. The causes were manifold: the national park lacks all natural predators, particularly the wolf. Hunting outside the national park was, until the 1970s, primarily focused on red deer stags — that is, trophy hunting — and was unable to curb population growth. Winter feeding outside the park additionally led to forest damage and winter mortality.

The high population levels led to repeated, massive winter die-offs, impairments of forest regeneration and agricultural crop losses. Between the 1950s and 1990s, this triggered political controversies that shook even the foundations of the national park. The verdict of the national park research itself is, however, nuanced. Fears of an ecological catastrophe were, from today's perspective, unfounded. Nevertheless, a hunting-based regulation of the red deer population was deemed appropriate. The solution was a two-stage hunt outside the protected area, namely a high hunt in September and a special hunt in late autumn, without violating the fundamental hunting ban within the national park.

Interspecific competition: not just idyll

Research findings from the Val Trupchun show that at high red deer densities, chamois increasingly retreat to less food-rich scree slopes. The horn growth of chamois kids correlates negatively with red deer density. A higher deer population also negatively affects the population growth rate of ibex. A comparable pattern is shown by a Polish study from the hunting-free Słowiński National Park. There, high red deer densities significantly displaced the roe deer population through resource competition. Self-regulation therefore does not automatically mean harmony for all species simultaneously. It can be associated with dominant species that displace others.

More on this: Chamois in Switzerland and Red deer in Switzerland

Compensatory reproduction: the strongest scientific counterargument

A central biological principle supports the position of hunting criticism: compensatory reproduction. Wildlife populations respond to losses from hunting with increased birth rates, earlier sexual maturity and larger litters.

The evidence is international and spans species. A French long-term study over 22 years showed that hunting pressure significantly increases the reproduction rate of wild boars. Normally, only the lead sow reproduces. If she is shot, all the females in the group reproduce. In Switzerland, according to the Federal Hunting Statistics, red deer populations rose from 23,332 animals in 2000 to over 40,000 in 2022 and 2023 (2025: 39,186), even though the number of kills practically doubled over the same period, from 7,036 to 13,636 (Swiss Hunting Statistics 2025). Recreational hunting preferentially targets males and thus trophies, which shifts the sex ratio in favour of fertile females.

International studies provide further evidence. Swedish researchers showed that female bears shorten the rearing period of their cubs in response to hunting pressure, in order to be able to reproduce again more quickly. A study from Washington State disproved the "compensatory mortality hypothesis" for cougars. Heavy hunting correlated with increased immigration, lower juvenile survival rates and a younger age structure, but not with the predicted population stabilisation. In black-backed jackals, hunting led to a younger age structure and an expanding rather than stable population, as the social control exerted by older animals was lost.

These findings support the core argument of hunting criticism: recreational hunting produces precisely the populations it claims to prevent.

More on this: Why recreational hunting fails as population control and Hunting myths: 12 claims critically examined

Where researchers genuinely disagree

Natural predators as a substitute for recreational hunting?

WSL researchers Andrea Kupferschmid and Kurt Bollmann show that wolves significantly alter the spatial behaviour of hoofed game and locally reduce browsing damage. However, this effect only applies to a limited extent, and the picture is more nuanced than simple causality. In the Calanda region, home to the first Swiss wolf pack, browsing damage to fir, maple and rowan trees in the core territory decreased noticeably. The influence of the lynx on roe deer browsing damage has also been demonstrated, including through work carried out by BOKU Vienna in the canton of St. Gallen.

At the same time, forestry associations such as the Swiss Forestry Association take a clear position: «Large predators such as lynx and wolf cannot solve the regeneration problem», although they do influence the spatial distribution and behaviour of ungulates. These associations therefore call for recreational hunting to be intensified. This is remarkable because the browsing damage situation has not improved under decades of recreational hunting but, according to the same data, has worsened since 2015 (see below).

Browsing damage: widespread problem or locally confined?

The 2025 Forest Report by the FOEN and the WSL confirms that in some areas excessive wildlife populations impair natural regeneration. At the same time, however, it identifies heat, drought, storms and harmful organisms as greater burdens. According to the WSL overview by Kupferschmid and Frei (2025, Schweizerische Zeitschrift für Forstwesen 176(3)), forestry experts in 18 cantons classify natural regeneration as unimpaired on roughly half of the assessed forest area; in 2015 it was still two thirds. At least 21 per cent falls into the two highest categories of severe impairment. That this situation has worsened despite some 30,000 recreational hunters speaks not for more recreational hunting but against it as an instrument. The question of browsing damage cannot be served with simple yes-or-no answers.

Transferability of the Geneva model

The hunting lobby's most common counter-position is that Geneva is too small and too urban, so the model is not transferable. The counter-argument is factually strong. Geneva is densely populated, has intensive viticulture, an international airport and direct border traffic with hunting-intensive areas of France and the canton of Vaud. If professional wildlife management works in this context, there is no structural argument against its transferability to larger, less densely populated cantons. However, scalability is a genuine research question. Geneva covers 282 square kilometres, the Grisons 7,105 square kilometres. Just under three full-time posts suffice for Geneva. How many would the Grisons need? Reliable model calculations are absent from the literature.

More on this: The forest–wildlife conflict in Switzerland and Wolf in Switzerland: facts, politics and the limits of hunting

Overview of international comparative findings

Canton of Geneva, since 1974: Biodiversity rising, ungulate populations stable, brown hare at a Swiss record high. Caveat: professional interventions remain necessary.
Swiss National Park, since 1914: Species diversity markedly increased, no ecological catastrophe. Caveat: the red deer problem of the 1980s required special measures outside the park.
Luxembourg, fox hunting ban since 2015: No epidemics, no explosion in fox populations. Caveat: short time series.
Yellowstone, wolf reintroduction: Behavioural changes in red deer, vegetation regenerating. Caveat: complex trophic cascades, not directly transferable to Central Europe.
Słowiński National Park, Poland, without hunting: Red deer displace roe deer through resource competition. Shows side effects even without predators.

More on this: The fox in Switzerland and Hunting and biodiversity: does hunting protect nature?

What needs to change

Recognition of the scientific evidence: In revisions of the hunting act, the federal government and cantons must take the empirical findings from Geneva, the National Park and international research into account as a basis for decision-making. Scientific evidence must not be overridden by lobby interests.
Fund long-term monitoring independently: An independently funded long-term study must document wildlife populations in Geneva, the National Park and comparable cantons with intensive hunting in parallel over at least twenty years. Only this will make the question of transferability empirically answerable.
Pilot cantons for hunting-free zones: Two to four Swiss cantons test the game warden model on defined areas with open cost calculation and transparent monitoring of success. Template motion: Game wardens instead of recreational hunters.
Disclosure of kill statistics: The development of populations despite rising kill figures, for example red deer from 23,000 to around 39,000 animals in 25 years with kills doubled, belongs in the public debate. Compensatory reproduction is not a marginal topic but a structural argument against the regulation narrative.
Dialogue between forestry and wildlife biology: The browsing damage issue is currently dominated by forestry associations that simultaneously cling to recreational hunting. A joint working group with wildlife biology, WSL, cantonal authorities and animal welfare organisations should develop viable alternatives.

Arguments: Objections to the self-regulation thesis, and what is actually true

«Without hunting, populations explode and nature collapses.» Geneva has disproved this claim for 50 years, the Swiss National Park for 110 years. In both systems, biodiversity has not collapsed but increased. The core thesis of the recreational hunting lobby is empirically disproved.

«The Geneva model is not transferable because Geneva is urban.» Geneva has an international airport, intensive viticulture and direct border traffic with regions of intensive hunting. If wildlife management works there, no structural argument speaks against it working equally well in less densely populated cantons. The question of scalability is a research task, not a refutation.

«Recreational hunting is necessary to regulate populations.» Compensatory reproduction shows the opposite. Swiss red deer populations rose from 23,000 (2000) to over 40,000 animals (2022), even though kills practically doubled; in 2025 the figure was 39,186. Recreational hunting produces the very populations it claims to prevent.

«Without hunting, the forest collapses due to browsing damage.» According to the WSL overview (Kupferschmid and Frei 2025), regeneration is unimpaired on around half of the assessed forest area and at least 21 per cent is severely affected, and this after decades of nationwide recreational hunting. The Forest Report 2025 names heat, drought and storms as greater pressures than browsing damage. Where wolves and lynx live, browsing damage declines locally.

«Predators alone cannot regulate populations.» That is correct, and no one claims otherwise. The hunting-critical position states: professional game wardens, supplemented by natural predators and sensible habitat design, are sufficient. Recreational hunting is not part of the solution here, but part of the problem.

«The red deer problem of the 1980s shows that hunting-free zones do not work.» The verdict of the national park research itself is nuanced: fears of an ecological catastrophe were unfounded from today's perspective. While hunting-based regulation outside the park was indeed warranted, the hunting ban within the park itself never had to be touched.

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Self-regulation is not a theory but a 50-year field experiment in Geneva and a 110-year one in the Swiss National Park. The data show: wildlife populations stabilise, biodiversity increases, the ecosystem does not collapse. Compensatory reproduction exposes recreational hunting as a structurally ineffective regulatory instrument. The real question is not whether a balance is possible without recreational hunting. The question is why political Switzerland has ignored this balance for decades.

IG Wild beim Wild compiles the scientific evidence, because an honest societal debate about recreational hunting must begin with facts, not myths. This dossier is continuously updated whenever new studies, figures or political developments require it.

More on the topic of recreational hunting: in our Dossier on hunting in Switzerland we bring together fact checks, analyses and background reports.