Constitutionalizing in the Anthropocene

Restoring Europe’s megafauna is a legal (and moral) obligation

May 25, 2022

[Photo credit: Elvira Martinez Camacho]

Large mammals (megafauna) have crucial roles to play in European ecosystems, but have suffered great losses in the Late Pleistocene and Holocene. In a new study, we find that restoring Europe’s megafauna as much as possible is a legal (and moral) obligation.

Megafauna: important, degraded, restored?

The megafauna of Europe is severely downsized. For millions of years, European landscapes resembled the Serengeti in terms of the diversity and abundance of large mammals. In addition to today’s deer, wild boar, ibex and occasional bison, lynx, wolves and brown bears, Europe used to be home to giant deer, wild horses, onagers (wild donkeys), aurochs, water buffalo, hippos, rhinos and elephants, as well as dholes (wild dogs), hyenas, leopards, lions, scimitar cats, moon bears and cave bears, to name a few.

Then, during a brief period spanning the Late Pleistocene and Holocene – the blink of an eye in geological and evolutionary terms – many of these large mammals, including all the very largest, disappeared from the continent. Others were decimated. The causeHomo sapiens. Given the crucial ecological roles of large mammals, the collapse of the megafauna has profound implications for the functioning of European ecosystems and for the prospects of biodiversity as a whole. Yet, it is possible to repair the damage to a significant extent. Depending on the species, this can be achieved by promoting natural comebacks, through active reintroductions, and through introductions of surrogates for extinct species.

Legal obligations to restore megafauna

Law and policy at national and international levels tend to influence such rewilding scenarios. The role of law can be positive, when it promotes or even requires restoration efforts, or negative, when it makes such efforts difficult or impossible. At any rate, the need for ecosystem restoration has been rising fast on intergovernmental agendas. For instance, 2021-2030 has been declared the United Nations Decade on Ecosystem Restoration. And the European Union (EU) has set ambitious restoration targets of its own.

Against this background, the question arises to what extent international law currently promotes European megafauna rewilding measures. To address this question, I teamed up with Jens-Christian Svenning, an Aarhus University ecologist and an expert on large mammals and their ecological functions. Combining our disciplines, we interpreted relevant legal instruments in light of the best scientific evidence available and international policy statements.

Our freshly published findings show that various legal instruments at global, pan-European, EU and other levels support or even require megafauna restoration efforts in Europe. Examples include the EU Habitats Directive, the Bern Convention on European Wildlife Conservation, the Biodiversity Protocol of the Carpathian Convention, and the Convention on Biological Diversity (CBD).

Especially important is Article 8(f) of the CBD, which lays down a demanding ecological restoration obligation for European governments and the EU itself. Our analysis shows that meeting this obligation not only requires providing sufficient space, connectivity and room for natural processes, but also restoring the diversity and densities of Europe’s megafauna as far as possible – which is in fact quite far.

Restoration scenarios

We traced the dimensions of the megafauna restoration challenge by listing all 74 terrestrial mammal species with an average weight of more than 10kg that would probably have occurred in Europe today, had it not been for our ancestors. Over half of this entire European megafauna has gone missing, and many surviving species have reduced ranges and numbers. Moreover, the biggest species have been hardest hit. When looking at the 35 species weighing over 100kg, the losses exceed 75%. And the weight class of over 1000kg, which included eight megaherbivores – hippo, rhinos, elephants – has been wiped out completely.

Furthermore, we categorized species in ways that make sense from a law and policy perspective. For instance, some species can make a comeback by themselves, as wolves are doing. Others can be reintroduced from elsewhere in Europe, such as wisent, or from beyond, such as onagers and moon bears from Asia, or hippos and spotted hyenas from Africa. Some species where the original wild forms are extinct, particularly aurochs and wild horses, can be replaced by back-breeding and rewilding domesticated descendants. The ecological roles of other globally extinct species can be restored only by introducing surrogates, such as de-domesticated Asian water buffalo taking the place of the extinct European water buffalo, and Asian elephants stepping into the niche left open by straight-tusked elephants. The role of law regarding such scenarios will vary according to the circumstances.

To comply with their obligations under the CBD and other legal instruments, governments will need to address legal obstacles currently hampering megafauna restoration. Important examples are the incongruous application of all kinds of veterinary, sanitary and animal welfare requirements to rewilded cattle and horses, and even to wisent. This affects issues such as transport, health inspections and medical treatment, supplementary feeding and the (im)possibility of leaving carcasses in the landscape to feed the circle of life.

SpeciesWays of restoringExample
Extant in EuropeNatural (re)colonizationWolf
Reintroduction / reinforcementEuropean bison
Extirpated in Europe but surviving elsewhereReintroductionLion
Globally extinct in the originally wild form(s), but surviving in domesticated (and often feral) formDe-extinction – back-breeding / feralization / ecological replacementAurochs
Globally extinctDe-extinction – genetic engineeringCave Bear
Ecological replacement / assisted colonizationAsian elephant

Moral obligations

It is easy to see how some of the rewilding scenarios mentioned above could be controversial – especially when involving dangerous animals, and species that are long gone from European societies’ collective memories because of the ‘shifting baseline syndrome’. In this connection, it is important to keep an eye on the big picture and on ethical obligations, some of which we discuss in addition to our scientific and legal analyses.

A particularly significant moral argument concerns North-South solidarity. Few people would (dare) argue that Europeans deserve privileges that people in Africa and Asia do not – in this case the privilege of living without unruly large mammals that can pose a threat to human interests, including human safety. Yet, such inequality is entrenched in the present global situation. Given what we know about the (pre)history of megafauna in Europe and across the globe, the current situation reflects a patently unfair situation, wherein the burden of conserving and restoring large mammals is put largely on the shoulders of countries in Africa and Southern Asia, where most megafauna remains. It would be manifestly unjust to expect poor and rapidly growing human populations in the Global South to keep preserving and co-existing with dangerous big animals, without also undertaking ambitious megafauna restoration efforts in Europe. Recently announced plans for dedicated EU legislation on ecological restoration present a golden opportunity to make this happen.

A Trouwborst & J-C Svenning (2022) Megafauna restoration as a legal obligation: International biodiversity law and the rehabilitation of large mammals in Europe. Review of European, Comparative and International Environmental Law.


  • Question to Arie Trouwborst:

    In which text do you find specific reference to legal requirement to restore megafauna in Europe? The international CDB 8(f) only says:

    (f) Rehabilitate and restore degraded ecosystems and promote the recovery of threatened species, inter alia, through the development and implementation of plans or other management strategies;

    Is it the EU adoption of the CBD which is more specific? Where do I find it?


  • Dear Arie Trouwborst,

    I have now read your legal interpretation in the original paper. While I am in favour of your arguments, I also think it is an interpretation that will and can be challenged. The solution, I think, would be to add to the CDB text very specifically that restoration can and must include restoration of extant megafauna as well as suitable surrogate species.

  • Dear Kenneth,
    Thank you for engaging with our blog and the underlying paper. Yes, interpretations can be contested. From an ecological restoration point of view, and for the sake of clarity, I would agree that it would be great to have a more specific provision in the CBD. An amendment does not seem likely, however, but a COP Decision confirming ‘our’ interpretation of Article 8(f) would also be helpful.
    Best wishes,

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