E. J. Milner-Gulland

Quantification of Extinction Risk: IUCN's System for Classifying Threatened Species

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species was increasingly used during the 1980s to assess the conservation status of species for policy and planning purposes. This use stimulated the development of a new set of quantitative criteria for listing species in the categories of threat: critically endangered, endangered, and vulnerable. These criteria, which were intended to be applicable to all species except microorganisms, were part of a broader system for classifying threatened species and were fully implemented by IUCN in 2000. The system and the criteria have been widely used by conservation practitioners and scientists and now underpin one indicator being used to assess the Convention on Biological Diversity 2010 biodiversity target. We describe the process and the technical background to the IUCN Red List system. The criteria refer to fundamental biological processes underlying population decline and extinction. But given major differences between species, the threatening processes affecting them, and the paucity of knowledge relating to most species, the IUCN system had to be both broad and flexible to be applicable to the majority of described species. The system was designed to measure the symptoms of extinction risk, and uses 5 independent criteria relating to aspects of population loss and decline of range size. A species is assigned to a threat category if it meets the quantitative threshold for at least one criterion. The criteria and the accompanying rules and guidelines used by IUCN are intended to increase the consistency, transparency, and validity of its categorization system, but it necessitates some compromises that affect the applicability of the system and the species lists that result. In particular, choices were made over the assessment of uncertainty, poorly known species, depleted species, population decline, restricted ranges, and rarity; all of these affect the way red lists should be viewed and used. Processes related to priority setting and the development of national red lists need to take account of some assumptions in the formulation of the criteria.

Wild meat: the bigger picture

Massive overhunting of wildlife for meat across the humid tropics is now causing local extinctions of numerous species. Rural people often rely heavily on wild meat, but, in many areas, this important source of food and income is either already lost or is being rapidly depleted. The problem can only be tackled by looking at the wider economic and institutional context within which such hunting occurs, from household economics to global terms of trade. Conservation efforts must be placed within a landscape context; a mosaic of hunted and no-take areas might balance conservation with continued subsistence use. Successful conservation of hunted wildlife requires collaboration at all scales, involving local people, resource extraction companies, governments and scientists.

One Hundred Questions of Importance to the Conservation of Global Biological Diversity

We identified 100 scientific questions that, if answered, would have the greatest impact on conservation practice and policy. Representatives from 21 international organizations, regional sections and working groups of the Society for Conservation Biology, and 12 academics, from all continents except Antarctica, compiled 2291 questions of relevance to conservation of biological diversity worldwide. The questions were gathered from 761 individuals through workshops, email requests, and discussions. Voting by email to short-list questions, followed by a 2-day workshop, was used to derive the final list of 100 questions. Most of the final questions were derived through a process of modification and combination as the workshop progressed. The questions are divided into 12 sections: ecosystem functions and services, climate change, technological change, protected areas, ecosystem management and restoration, terrestrial ecosystems, marine ecosystems, freshwater ecosystems, species management, organizational systems and processes, societal context and change, and impacts of conservation interventions. We anticipate that these questions will help identify new directions for researchers and assist funders in directing funds.

Identification of 100 fundamental ecological questions

Summary 1. Fundamental ecological research is both intrinsically interesting and provides the basic knowledge required to answer applied questions of importance to the management of the natural world. The 100th anniversary of the British Ecological Society in 2013 is an opportune moment to reflect on the current status of ecology as a science and look forward to high-light priorities for future work.

Conservation: Reproductive collapse in saiga antelope harems

A common assumption is that breeding in polygnous systems is not limited by the number of males because one male can inseminate many females. But here we show that reproductive collapse in the critically endangered saiga antelope (Saiga tatarica tatarica) is likely to have been caused by a catastrophic drop in the number of adult males in this harem-breeding ungulate, probably due to selective poaching for their horns. Fecundity and calf survival are known to be affected by markedly skewed sex ratios, but in the saiga antelope the sex ratio has become so distorted as to lead to a drastic decline in the number of pregnancies — a finding that has implications both for the conservation of the species and for understanding the reproductive ecology of polygynous ungulates.

The relative roles of density and climatic variation on population dynamics and fecundity rates in three contrasting ungulate species

The relative influences of density–dependent and–independent processes on vital rates and population dynamics have been debated in ecology for over half a century, yet it is only recently that both processes have been shown to operate within the same population. However, generalizations on the role of each process across species are rare. Using a process–orientated generalized linear modelling approach we show that variations in fecundity rates in populations of three species of ungulates with contrasting life histories are associated with density and winter weather in a remarkably similar manner. However, there are differences and we speculate that they are a result of differences in size between the species. Much previous research exploring the association between vital rates, population dynamics and densitydependent and–independent processes has used pattern–orientated approaches to decompose time–series into contributions from density–dependent and–independent processes. Results from these analyses are sometimes used to infer associations between vital rates, density and climatic variables. We compare results from pattern–orientated analyses of time–series with process–orientated analyses and report that the two approaches give different results. The approach of analysing relationships between vital rates, density and climatic variables may detect important processes influencing population dynamics that timeseries methodologies may overlook.

Biodiversity offsets in theory and practice

Biodiversity offsets are an increasingly popular yet controversial tool in conservation. Their popularity lies in their potential to meet the objectives of biodiversity conservation and of economic development in tandem; the controversy lies in the need to accept ecological losses in return for uncertain gains. The offsetting approach is being widely adopted, even though its methodologies and the overriding conceptual framework are still under development. This review of biodiversity offsetting evaluates implementation to date and synthesizes outstanding theoretical and practical problems. We begin by outlining the criteria that make biodiversity offsets unique and then explore the suite of conceptual challenges arising from these criteria and indicate potential design solutions. We find that biodiversity offset schemes have been inconsistent in meeting conservation objectives because of the challenge of ensuring full compliance and effective monitoring and because of conceptual flaws in the approach itself. Evidence to support this conclusion comes primarily from developed countries, although offsets are increasingly being implemented in the developing world. We are at a critical stage: biodiversity offsets risk becoming responses to immediate development and conservation needs without an overriding conceptual framework to provide guidance and evaluation criteria. We clarify the meaning of the term biodiversity offset and propose a framework that integrates the consideration of theoretical and practical challenges in the offset process. We also propose a research agenda for specific topics around metrics, baselines and uncertainty.

Management strategy evaluation: a powerful tool for conservation?

The poor management of natural resources has led in many cases to the decline and extirpation of populations. Recent advances in fisheries science could revolutionize management of harvested stocks by evaluating management scenarios in a virtual world by including stakeholders and by assessing its robustness to uncertainty. These advances have been synthesized into a framework, management strategy evaluation (MSE), which has hitherto not been used in terrestrial conservation. We review the potential of MSE to transform terrestrial conservation, emphasizing that the behavior of individual harvesters must be included because harvester compliance with management rules has been a major challenge in conservation. Incorporating resource user decision-making required to make MSEs relevant to terrestrial conservation will also advance fisheries science.

A model of incentives for the illegal exploitation of black rhinos and elephants : poaching pays in Luangwa Valley, Zambia

1. The decline of Africas rhinos and elephants over the past decade has alarmed conservationists, yet little is known about the interaction between law enforcement and the economic incentives for illegal exploitation. This study models the relationships between financial gains, detection and penalties for poaching rhinos and elephants in Luangwa Valley, Zambia during 1979-85. 2. We explore how sentencing strategies affect the decisions of poachers in relation to changes in detection rate, penalty and economic variables. We show that a penalty which varies with the output of a poacher is, in theory, a more effective tool against poaching than a fixed penalty. However, the probability of capture is a highly significant factor in the poachers decision to hunt. 3. The incentives to poach are modelled for an open access situation, the industry structure for a local poacher, and for a monopolist who employs organized gangs. Organized and local gangs have very different reactions to law enforcement. Local poachers will respond to local investment schemes, but the deterrence of organized gangs can only be achieved with improved law enforcement operations.

Effect of Local Cultural Context on the Success of Community-Based Conservation Interventions

Conservation interventions require evaluation to understand what factors predict success or failure. To date, there has been little systematic investigation of the effect of social and cultural context on conservation success, although a large body of literature argues it is important. We investigated whether local cultural context, particularly local institutions and the efforts of interventions to engage with this culture significantly influence conservation outcomes. We also tested the effects of community participation, conservation education, benefit provision, and market integration. We systematically reviewed the literature on community-based conservation and identified 68 interventions suitable for inclusion. We used a protocol to extract and code information and evaluated a range of measures of outcome success (attitudinal, behavioral, ecological, and economic). We also examined the association of each predictor with each outcome measure and the structure of predictor covariance. Local institutional context influenced intervention outcomes, and interventions that engaged with local institutions were more likely to succeed. Nevertheless, there was limited support for the role of community participation, conservation education, benefit provision, and market integration on intervention success. We recommend that conservation interventions seek to understand the societies they work with and tailor their activities accordingly. Systematic reviews are a valuable approach for assessing conservation evidence, although sensitive to the continuing lack of high-quality reporting on conservation interventions.