Conservation management is deploying increasingly intensive strategies to maintain biodiversity and ecosystem function in response to global anthropogenic threats.These strategies include intentionally introducing and eradicating species around the world via assisted migration, rewilding, biological control, invasive species eradications, and gene drives -management actions which have become highly contentious because of their 2 This article is protected by copyright. All rights reserved. potential for unintended consequences. We conducted a global literature review of these conservation actions to quantify how often unintended outcomes occur and to elucidate their underlying causes. We found that studies reported intended outcomes in 51% of cases, a combination of intended outcomes and unintended outcomes in 26% of cases, and strictly unintended outcomes in 10% of cases. Hence, unintended outcomes were reported in 36% of all cases evaluated. In evaluating overall conservations outcomes (weighing intended vs unintended effects), some unintended effects are fairly innocuous relative to successful conservation objectives whereas others result in serious unintended consequences in recipient communities. Importantly, we also found that studies that assessed a greater number of community interactions with the target species were more likely to report unintended outcomes, suggesting that unintended consequences may be under-reported due to insufficient vetting. Most reported unintended outcomes arose from direct effects (68%) or simple density-mediated, indirect effects (25%) linked to the target species, with only a few documented cases arising from more complex interaction pathways (7%). Therefore, most unintended outcomes involved simple interactions that could potentially be predicted and mitigated through more formal vetting. To address this shortfall, we applied foundational concepts from community ecology to develop a community assessment framework which can be used to systematically screen for potential impacts on nontarget species prior to implementing conservation actions. We propose that incorporating this approach to screen proposed conservation actions could help reduce unintended consequences from intentional species introductions and eradications for conservation.
Human‐dominated landscapes are being recolonized by large carnivores, thereby increasing conflicts worldwide via predation of livestock and harvested wildlife such as ungulates. Recent meta‐analyses have shown that predator control (hereafter, predator removal) has mixed success in reducing livestock predation. Yet, it is unknown how effective predator removal is in decreasing predation on ungulates due to a lack of quantitative synthesis, despite the long history of implementation in North America. We quantified the demographic responses of ungulate survival and recruitment rates, abundance, and population growth to experimental predator removal and identified the ecological and experimental design factors affecting ungulate responses to predator removal. We conducted a literature review of management and natural experiments to increase ungulate demography finding 52 predator removal experiments and 10 natural experiments from 47 publications. We then conducted a meta‐analysis to determine the overall effect size and factors which increased ungulate demography during predator removal. Lastly, we tested for evidence of publication bias and experimental rigour for these experiments. We found that predator removal in both management and natural experiments increased ungulate demographic responses by 13% (95% CI = 4.1%–23%), yet prediction intervals overlapped with 0 (95% PI = −34% to 93%). Focusing just on management removals, ungulate demographic responses increased only by 7.8% (95% PI = −32% to 72%), indicating that future experiments could have negligible effects. Predator removal in both management and natural experiments was more successful in improving the demography of young (e.g. recruitment ES = 44%, 95% CI = 13%–83%) but equivocal in improving adult survival (ES = 5.4%, 95% CI = −18% to 36%) and ungulate abundance (ES = 13%, 95% CI = −17% to 31%). The low and variable effectiveness of predator removal for ungulate populations might be linked to ungulates' slow life history and the compensatory mortality of carnivores on ungulates, though effects were stronger on endangered prey. We identified the experimental design factors that led to greater uncertainty in ungulate responses to predator removal, including lack of randomization, low replication and short temporal length. Lastly, we found evidence of publication bias, where experiments with poor rigour and negative effects (i.e. reduced ungulate demography following predator removal) were under‐reported. Synthesis and Applications. We recommend future predator removal experiments be conducted with a more rigorous experimental design to overcome these weaknesses, especially for endangered species where predator removal may work more effectively. We suggest that managers attempting to evaluate experimental practices to increase ungulate populations through predator removal could employ an open standards framework akin to the ‘Open Standards for the Practice of Conservation’ framework.
1. Biological organisms are increasingly being introduced and eradicated in an effort to maintain biodiversity and ecosystem function in the face of anthropogenic threats. However, these conservation actions can have unintended consequences to non-target species. Careful vetting of these actions using ecological modelling tools could help predict and avoid unintended consequences.2. Qualitative modelling tools, such as fuzzy interaction webs (FIWs), allow for qualitative rankings of community properties (e.g. interaction strength = high, medium, low) in combination with quantitative information to predict management outcomes. These tools have lower data requirements than strictly quantitative models, facilitating their use for communities lacking comprehensive parameterization. However, no studies have evaluated the efficacy of FIWs for predicting unintended consequences against empirically documented outcomes.Moreover, there is no process for systematically identifying which species to incorporate in community-level conservation assessments to overcome model structure uncertainty. Finally, there is a need to make qualitative modelling tools more accessible for conservation practitioners.3. We applied FIWs to the case study of lake trout introduction into Yellowstone Lake, Yellowstone National Park, to assess its ability to predict documented community-level outcomes from an intentional species introduction. Next, we used the case study of the intentional red squirrel introduction to Newfoundland to show how a community assessment framework can help define the community interaction web needed for applying a FIW. Lastly, we introduced a userfriendly web interface (https://matrix.mpgra nch.com/#/) for applying FIWs to conservation questions. 4. We found that the FIW predicted previously documented directional changes in the abundance of community components relatively well in the Yellowstone Lake case study, even with minimal knowledge of the system. The community | 2323
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