Renewed coexistence: learning from steering group stakeholders on a beaver reintroduction project in England

Species reintroductions are growing in popularity, and example motivations include supporting species populations or the restoration of ecosystem function. Interactions between humans and the reintroduced species are likely to occur post-reintroduction. Coexistence between humans and wildlife is adaptive and dynamic, in part requiring management of conflicts between humans and wildlife, or of conflicts between humans over wildlife management. We seek to learn from the experiences of steering group members in a Eurasian beaver (Castor fiber) project in England and identify how governance of coexistence with reintroduced species may differ from the governance of coexistence with species that are already present in the landscape. Using a qualitative thematic analysis of an online survey, we identify a series of lessons in six key areas: (1) project governance, (2) stakeholder engagement, (3) research and monitoring programme, (4) strategy to manage arising conflicts, (5) public engagement, and (6) broad perspectives on reintroduction trials. We advocate for reflective evaluation as an essential component of reintroduction projects to enable knowledge-sharing from experiences, leading to improved practices in the future. Reflecting on our analysis, we identify and define ‘Renewed Coexistence’—a new term that draws on pre-existing coexistence knowledge but identifies the unique elements that relate to governing coexistence with reintroduced species.

Trophic niche overlap and abundance reveal potential impact of interspecific interactions on a reintroduced fish

Conceptually trophic niche overlap and species abundance can describe the strength and number of interspecific trophic interactions to determine the competitive impact on reintroduced species or other ecosystem changes. We use an example with young-of-year (YOY) Atlantic salmon (<i>Salmo salar</i>) reintroductions to determine if trophic niche overlaps and abundances limit restoration success. Using seasonal stable isotopes and abundance estimates for invertivorous fishes in three Lake Ontario tributaries, we assessed community isotopic structure, trophic niche overlap, and the impact of the niche overlap by incorporating relative abundance. Brown trout (<i>Salmo trutta</i>) YOY could be a strong competitor with a high trophic niche overlap with Atlantic salmon YOY but at lower abundances relative to Atlantic salmon minimizes impact. Stream resident fish communities appeared to partition resources across seasons such that abundant species had low trophic niche overlap to minimize overall competition with Atlantic salmon YOY given available resources, indicating niche complementarity. Through joint consideration of trophic overlap and abundance using our conceptual model, the competitive impact of community composition on a reintroduced species could be assessed.

Where to rewild? A conceptual framework to spatially optimize ecological function

Rewilding is an approach aiming at restoring ecosystems to a self-sustaining state by restoring ecological function through active reintroductions or passive management. Locations for most rewilding-through-reintroduction efforts today are selected based on the suitability of the habitat for the reintroduced species, often with little consideration of where the ecological function is most needed. We developed the Spatial Planning of Rewilding Effort (Spore) framework to identify priority locations for rewilding projects through simultaneous consideration of habitat suitability and provisioning of ecological function. We use the island of Guam as a case study for a potential rewilding project, as the island has functionally lost all native seed dispersers as a result of the invasive brown treesnake ( Boiga irregularis ). The Såli (Micronesian starling, Aplonis opaca ) is a good candidate for rewilding to restore ecological function, because it is an effective seed disperser with a localized remnant population. Using Spore, we identify three priority areas for the restoration of seed dispersal, each subdivided into management units. By recognizing the influence of landscape structure and the behaviour of the reintroduced species on the spatial pattern of the function provided by that species, this approach should lead to improved ecological outcomes.

Drug efficacy of ivermectin against primary nematodes parasitizing captive Przewalski’s horse (Equus ferus przewalskii) after ten years of annually treatment

SummaryReintroduction of endangered species to natural habitat is considered as an important tool for conservation. The effect of drug management on captive population of reintroduced species is largely neglected. Decreased drug efficacy could pose a substantial threat to health of animals. More importantly, captive population without proper drug administration could act as transmission medium of resistance nematodes to wild population, making it important to delay the occurrence of drug resistance in captive population. Ivermectin have been used in captive Przewalski’s horse (Equus ferus przewalskii) to eradicate intestinal parasitic nematodes annually, while no available studies describing the drug efficacy in the recent ten years. Here, fecal egg counts pre- and post-treatment were performed with ivermectin through individual trace. Both large and small strongyles were identifi ed by larval culture. The fecal egg count reduction was almost 100% based on egg counting data of 448 samples from 13 Przewalski’s horses. Feces of two Przewalski’s horses were sampled for successive 20 days. Eggs per gram feces usually increased dramatically at the period of 1 – 2 post-treatment days and declined persistently to 0.0 within 15 days. A sustained high ivermectin efficacy against neither Parascaris equorum nor strongyles was indicated, which can be partly explained by the low deworm frequency.

Reconciling social justice and ecosystem-based management in the wake of a successful predator reintroduction

The reintroduction of a previously extirpated predator can engender conflict when the reintroduced species depletes customary fisheries to which indigenous communities have constitutionally protected rights. In the case of sea otter (Enhydra lutris) recovery on the west coast of North America, not only is Canada’s Species at Risk Act in conflict with Indigenous rights, but it also illuminates gaps in the principles of ecosystem-based management (EBM), such as equity and social justice. Broadly, we ask in this paper how EBM might be advanced if Indigenous communities were viewed as components of ecosystems having rights to a sustainable future equal to other components. Specifically, we explore evidence of sea otter management among precontact Northwest Coast societies and a contemporary co-managed system proposed by the Nuu-chah-nulth First Nations that would combine research with refinement of traditional hunting practices. We show that barriers persist through lack of knowledge of past controlled hunts, ignorance of recent experiences of successful community-based clam management, distrust of Indigenous capacity to self-manage or co-manage a hunt, and divergent values among actors.

Reintroductions of birds and mammals involve evolutionarily distinct species at the regional scale

Reintroductions offer a powerful tool for reversing the effects of species extirpation and have been increasingly used over recent decades. However, this species-centered conservation approach has been criticized for its strong biases toward charismatic birds and mammals. Here, we investigated whether reintroduced species can be representative of the phylogenetic diversity within these two groups at a continental scale (i.e., Europe, North and Central America). Using null models, we found that reintroduced birds and mammals of the two subcontinents tend to be more evolutionarily distinct than expected by chance, despite strong taxonomic biases leading to low values of phylogenetic diversity. While evolutionary considerations are unlikely to have explicitly driven the allocation of reintroduction efforts, our results illustrate an interest of reintroduction practitioners toward species with fewer close relatives. We discuss how this phylogenetic framework allows us to investigate the contribution of reintroductions to the conservation of biodiversity at multiple geographic scales. We argue that because reintroductions rely on a parochial approach of conservation, it is important to first understand how the motivations and constraints at stake at a local context can induce phylogenetic biases before trying to assess the relevance of the allocation of reintroduction efforts at larger scales.