Who Let the Frogs out? Illicit and Unregulated Species Translocations

Abstract

The IUCN definition encompasses population reinforcement (boosting existing populations with new individuals), reintroductions (movement of locally extinct species into their former range), assisted colonisation (movement of species to new, non-native areas to aid their conservation) and ecological replacement (movement of species to places to perform the ecological role of an extinct species). The IUCN best practice guidelines stipulate engagement with other actors, such as local communities, but I focus on the regulatory engagement as regulators’ work cover multiple interests, rather than the narrower focus of other actors. With the rise of rewilding type ideas and the focus on species’ ecological role, it is also a statement that their activities and ecosystem functions, such as beaver herbivory and dam building, should be present. Beavers illicitly released in the UK, Italy, Belgium and other locations have been genetically linked to populations in Bavaria, southern Germany, rather than more geographically proximate populations, indicating a continent-wide illicit trade in beavers for translocation (Bertolino et al. 2023; Campbell-Palmer et al. 2021; Pucci et al. 2021).

An odd conservation phenomenon is the emergence of new populations of species, distant from all known wild populations, without the knowledge of government agencies or conservation organizations. Whether it is beavers appearing in Great Britain, Belgium, central or Southern Italy north-eastern or southern Spain, or Tasmanian devils appearing on islands in the Bass Strait, it appears that humans are assisting species in moving around, apparently for conservation reasons, a ‘covert’ or ‘guerrilla’ corollary to officially sanctioned conservation translocations (Vaccaro and Beltran 2009; Bode 2021; Bertolino et al. 2023; Thomas 2022; Gaywood 2024). This is not a new thing—in the early 20^th century, the Swiss Alps were repopulated with Ibex illicitly taken from the remnant Italian population (Maudet et al. 2002)—but such translocations may be increasing. These species movements are likely—underreported and are certainly an under-examined conservation phenomenon. This may reflect the general lack of attention given to unofficial and informal social phenomena and civil disobedience in conservation (Holmes 2022), but also the methodological challenges in studying rule-breakers and guidance-benders who would largely rather stay hidden (Nuno and St John 2015). Such incidents are worth considering as part of the wider translocation system, alongside conservation organisations, regulators, and land managers, as they are social and ecological experiments which are reshaping ecosystems and conservation politics, including on ‘licit’ translocations. Whilst illicit translocations have many similarities to their licit counterparts, there are important differences, not least because they are located beyond the boundaries of currently accepted processes and candidate species for translocation, and lack consent and oversight. More than this, they prompt tricky ecological and political dilemmas for conservationists in deciding what life should be present where, and how this decision is made, revealing important ethical differences amongst conservationists on issues such as risk, native-ness and how conservation should relate to wider society.

Humans have released species into the wild for millennia for various purposes, including conservation translocations, defined as “the intentional movement and release of a living organism where the primary objective is a conservation benefit” (IUCN/SSN, 2013, p2). The IUCN definition encompasses population reinforcement (boosting existing populations with new individuals), reintroductions (movement of locally extinct species into their former range), assisted colonisation (movement of species to new, non-native areas to aid their conservation) and ecological replacement (movement of species to places to perform the ecological role of an extinct species). For unofficial translocations, a number of problematic labels have been used. Bode (2021) refers to ‘covert’ translocations, which is misleading as many happen in open sight. Interviewees in Thomas (2022) mention ‘guerrilla’ translocations, which is an unhelpful metaphor for a conflict against a more powerful opponent, as well as risking homophone-related confusion. Here I focus on how such translocations are defined by lack of engagement with regulations and regulators, and I refer to illicit and unregulated translocations. Illicit refers to conservation releases of species in contravention of relevant laws, unregulated refers to releases which, although not breaking laws, fail to engage with relevant conservation authorities, in contravention of IUCN best practice guidelines on conservation translocation (IUCN/SSN, 2013). The IUCN best practice guidelines stipulate engagement with other actors, such as local communities, but I focus on the regulatory engagement as regulators’ work cover multiple interests, rather than the narrower focus of other actors. Data on ‘official’ translocations is imperfect and incomplete, and, by their frequent covert nature, data on illicit and unregulated translocations is even more scarce and limited. What we do know is that—like their official counterparts—they have a long history, are receiving increasing attention, and they involve a wide range of taxa, even if public and political attention focuses on a few high-profile charismatic fauna.

At its most basic, a conservation translocation of a species is a political statement that this species should be present in that place. Conservationists seek to translocate species for various reasons; to conserve that species, to restore or enhance ecosystem function, and to atone for past extirpations (IUCN/SSC 2013; Jorgensen 2019). The little we know about the motivations for illicit and unregulated translocations aligns with these reasons. Illicit and unregulated translocations are informal political actions to make this statement a reality, in the face of official inability or unwillingness to do so. With the rise of rewilding type ideas and the focus on species’ ecological role, it is also a statement that their activities and ecosystem functions, such as beaver herbivory and dam building, should be present. It implicitly states that the moral case for bringing back these species and their functions overrides the need to follow laws and rules. They become acts of civil disobedience. This is the inverse of a much better understood part of the informal politics of conservation, where species are killed as part of resistance against conservation, such as retaliatory or anticipatory killing of predators by herders, where such actions are political statements that these species should not be present (Holmes 2007). There are also rumours of ‘sabotage’ type translocations, where populations of protected species such as newts are deliberately moved to sites earmarked for building or infrastructure development, to hamper attempts to build on them. In these cases, the implied statement that the species should be present is mixed with a presumed intent that the development should not happen.

As with other instances of informal politics in conservation (Holmes 2007), understanding who did what, and why, is challenging, and data is generally poor. It is often difficult to distinguish between illicit and unregulated conservation translocations, and releases for other purposes such as animal rights and game management, or accidental escapes from enclosures, or indeed natural phenomena such as recolonization or range expansion. The ambiguity, and presence of such plausible and innocent explanations, can allow illicit and unregulated translocations to remain covert, and keep scrutiny from perpetrators. In some instances, we can be reasonably confident that there were illicit or unregulated translocations, as there is a frequent and consistent story about who undertook the release, and why, and open praise for those who did so (Gow, 2020; Matthews and Kendal 2023). Many of the instances I discuss here are based on such inference, or because of off-the-record information. On occasion, perpetrators may admit to their actions (Barkham, 2023), though there is only one case of a conviction for illicit reintroductions—of beavers in Belgium (Gow, 2020). As part of this informal politics of conservation, illicit translocation broadens the idea of who is a conservation translocator, going beyond those working for conservation organisations to individual actors acting outside of conservation regulations, and the conservation ‘mainstream’, willing to break or bend rules for their environmental beliefs. This is not to dismiss them as ignorant or amateurish. The act of obtaining, transporting—sometimes across national borders and oceans—and releasing larger mammals such as beavers, Tasmanian devils and Eurasian lynx, all whilst remaining undetected, reflects considerable expertise and investment of time, money and effort. Beavers illicitly released in the UK, Italy, Belgium and other locations have been genetically linked to populations in Bavaria, southern Germany, rather than more geographically proximate populations, indicating a continent-wide illicit trade in beavers for translocation (Bertolino et al. 2023; Campbell-Palmer et al. 2021; Pucci et al. 2021). Other species are much simpler, easier and cheaper—butterfly pupae and eggs and wildflower seeds can be cheaply and easily bought on the internet, and delivered by mail. As with licit reintroductions, illicit and unregulated reintroductions can fail to establish populations (Barkham 2023), though there are notable successes—for example, there are more than 1000 wild beavers in Scotland, the vast majority of which descend from illicit releases rather than the subsequent licensed ‘trial’ release (NatureScot 2023).

We can also infer that illicit and unregulated translocators see significant problems with existing regulations and best practice, as they do not engage with them, and that the moral imperative for translocations over-rides the need to follow guidelines. Existing regulations are criticised by some conservationists as being too cautious, slow, and bureaucratic in the face of a perceived urgent need for translocation, and the wealth of knowledge in how to do it (Gow 2020; Thomas 2022). Following the illegal release of four lynx (Lynx lynx) in Scotland, in what is widely but not universally assumed to be an illicit translocation, one national conservation organisation condemned the release yet stated that “We understand the frustration that incentivises those responsible for illegal releases, who are concerned about the biodiversity crisis and feel there is a lack of support from government to support and enable reintroductions” (Mammal Society 2025).

Illicit and unregulated translocations are a divisive topic amongst conservationists. Following the illicit release of beavers in Italy, which Bertolino et al. (2023) considered to be a dangerous and reckless act, they urged “competent authorities to remove these animals”. Pucci et al. (2021) had the opposite view, arguing that “Immediate actions should be promoted to monitor potential expansion, preserve this population”. Underpinning such divisions are different views amongst conservationists towards uncertainty, caution and the correct levels of risk in conservation. For example, there are concerns that illicit and unregulated translocations are a significant biosecurity risk, as it is assumed that these species will not have been checked for disease or parasites prior to release, although beavers illicitly introduced to the UK were subsequently trapped and tested negative for parasites (Campbell-Palmer et al. 2021). There are also controversies over whether the illicitly released species are from an appropriate genetic source, similar to the original population and adapted to local conditions, as per the IUCN guidelines on translocations (Barkham 2023). However, given that the genetics of the extinct populations are not always clear, and given differences in opinion amongst conservationists about the extent to which issues of genetic provenance are vital concerns or unnecessary pedantry, this same controversy can apply to licensed and licit reintroductions, although in these instances it is possible to have a discussion prior to any release. Similarly, there is controversy over whether some illicit and unregulated translocations should be considered as ‘native’ or not, particularly where the historical and palaeontological record is uncertain or when baselines for being ‘native’ are contested, yet illicit reintroductions may establish a population of these species without a more open discussion (Dubey et al. 2019). Controversies may be exacerbated when there is disagreement between understandings of whether a species is native or not between legislation, different disciplines within science, and lay understandings—for example, over whether illicitly translocated beavers should be considered “native1” to Britain (Holmes et al. 2022). There are also concerns over animals’ welfare. Given their covert nature, species released illicitly and without licence may not go through appropriate habituation, and may not survive—for example, the four lynx released in mid-winter in Scotland were poorly habituated, and one died shortly after capture.

Beyond these direct impacts on ecosystems and individuals, illicit and unregulated translocations can reshape conservation politics and society's relationships with the wild. It can feed into narratives that conservationists are out-of-touch, urbanite elites, contemptuous of rural residents, and who recklessly and arrogantly decide what species rural people should live with, without consultation and in defiance of regulations (von Essen 2017). Such acts fuel rumours, common in conservation, about species translocations and the ‘true’ origins of translocated species, and the intentions of conservationists towards local people, further strengthening narratives about arrogant conservationists (Holmes 2022). Hostility towards illicit translocations can generate hostility locally to the translocated species, which can be directly harmed, and to opposition to further conservation actions (Holmes et al. 2024). Whilst licit translocations can generate hostility, illicit reintroductions may generate more, because of a lack of accountability for the release, and in some cases post-release management, that might mitigate their impact (Holmes et al. 2024). By implication, releasers do not consider it sufficiently important to foster consent, or take steps to generate human-wildlife coexistence. As such, they have lower legitimacy than licit translocations and natural recolonizations. Hostility to illicit translocations can undermine wider translocation agendas—for example, following the illicit release of lynx in Scotland, the government announced that there would be no reintroductions of any large predator to Scotland (BBC, 2025). This is a major set-back to a well-organised and funded project operating in Scotland in recent years to secure public consent and government approval for a licit lynx reintroduction to Scotland. Yet illicit and unlicensed reintroductions may also generate public support for translocations, by prompting debates about what species belong, challenge shifted baselines about what is assumed to be native. Thomas’ (2022) study of beaver reintroductions in England indicates that illicit translocations can lead to political support for further, licit translocations. The initial illicit introductions served as an experiment proving that these species can thrive in that place, and forced a decision on whether their presence should be permitted. Tolerance, as a pragmatic response, made their presence de facto legal (Thomas 2022). Indeed, as a result of illicit releases leading to well-established populations, beavers have been re-classified as ‘ordinarily resident’, that is, not non-native, in England (Natural England 2024). Yet, as the lynx case shows, an ecologically and socially unsuccessful illicit translocation can in some instances harm wider translocation efforts. Indeed, part of Bertolino et al. (2023) argument for capturing illicitly introduced beavers in Italy was a fear of the consequences for broader translocation agendas, not just from potential ecological impacts but also the wider political and social impacts.

More broadly, conservation authorities face dilemmas in how to react to illicit and unlicensed translocations. Given the covertness of such translocations, the cryptic nature of many species, and the fact that illicit and unregulated population reinforcements may be extremely difficult to distinguish from the original populations, authorities may only notice the presence of translocated specimens long after they were moved and become established. Illicitly translocated specimens may fall into legal grey areas—there may be doubt over whether a species reintroduced without proper process after an absence of centuries would be classed as native or not, or whether a translocated specimen is in breach of biosecurity or other regulations. Authorities may be therefore influenced by what is pragmatic and possible, rather than necessarily desirable according to prescribed criteria. Yet, as the case of illicit reintroductions of beavers to England and Scotland shows, a decision not to act ends up being a choice that has consequences, affecting the animals themselves, the wider ecology, and the broader politics of species reintroduction (Thomas 2022a, b). The situation becomes an ecological and social experiment in translocation ecology and politics, with humans and non-humans as non-consenting participants. It is therefore vital to understand the intentions of those who undertake illicit and unregulated translocations, and what they saw as the potential and desirable outcomes of these experiments.

Illicit and unregulated species translocations are rarely considered in conservation. They are both acts of civil disobedience and social and ecological experiments, conducted with less consent and preparation than most translocations. They are an ecologically and socio-politically important part of the translocation system, because they can reshape it. Whilst many concerns over illicit and unregulated translocations—on ecological consequences, animal welfare, biosecurity, risk, human-wildlife coexistence, consent of local populations—also apply to licit translocations, they are more pressing with illicit and unregulated translocations because the lack regulatory oversight, democratic discussion and accountability.

As researchers, we should seek to understand not just their ecological impacts, but also their social, political and cultural aspects. We need to engage with illicit and unregulated translocators, to understand their work and methods, and to do so effectively and ethically. We can do so by adopting approaches from criminological and anthropological studies of rule-breakers, such as methods for sensitively measuring rule-breaking, or theories of how rule-breakers justify their behaviour, as has been applied in other areas in conservation (Nuno and St John 2015; Moreto and Elligson 2025). Regulators, researchers and politicians must consider these translocations as acts of disobedience and as experiments. As political acts, implementing strong enforcement appears unproductive, given that illicit translocations are largely undetectable and rules unenforceable. Laissez faire approaches of ignoring them risks unintended legitimization, and encouraging more illicit translocations. A more productive approach might be to understand the motives, and consider what might incentivise illicit and unregulated translocators to engage with regulations and best practice. To be better prepared to deal with future illicit or unregulated translocations, the most important step that regulators could take is to pre-empt these released and develop appropriate taxa-specific strategies for when they occur, making timely decisions, and communicate these clearly. These should take into account the potential political, ecological and social impacts of choosing to remove the translocated species or not, considering the feasibilities of doing so, and recognise that taking no action is a decision in itself. These translocations are not going away, and must be taken seriously.

Acknowledgements

I thank members of the England Species Translocation Taskforce, particularly Delphine Pouget, Karim Vahed, and Jenny McPherson, as well as Filippo Marino, Hanna Pettersson, Darragh Hare and David Bavin, for their helpful suggestions. I also thank the individuals who have provided me with off-the-record information and insight, and I will respect their privacy and confidentiality.

Data Availability Statement

This paper does not use primary data.

Ethics statement

This paper does not contain any original data. Whilst informal conversations have shaped my thinking, all cases and instances explicitly mentioned and identified are from the published literature.

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