A growing literature argues for evidence-based conservation. This concept reflects a wider approach to policy-making and follows thinking in medicine, in which rigorous, objective analysis of evidence has contributed to widespread improvements in medical outcomes. Clearly, conservation decisions should be informed by the best information available. However, we identify issues relating to the type and sources of evidence commonly used and the way evidence-based conservation studies frame policy debate. In this paper we discuss two issues; firstly, we ask ‘what counts as evidence?’ (what is meant by evidence, and what kind of evidence is given credibility). We conclude that evidence-based conservation should adopt a broad definition of evidence to give meaningful space for qualitative data, and local and indigenous knowledge. Secondly, we ask ‘how does evidence count?’ (the relationship between evidence and the policy-making process). We conclude that there should be greater recognition that policy-making is a complex and messy process, and that the role of evidence in policy making can never be neutral. In the light of these issues we suggest some changes to build on developing practice under the title evidence-informed conservation. The change in terminology is subtle, yet it has profound implications in that it calls for a re-positioning and re-understanding of conservation science as one source of information among many for decision-makers.

The Sumatran rhinoceros Dicerorhinus sumatrensis is on the brink of extinction. Although habitat loss and poaching were the reasons of the decline, today's reproductive isolation is the main threat to the survival of the species. Genetic studies have played an important role in identifying conservation priorities, including for rhinoceroses. However, for a species such as the Sumatran rhinoceros, where time is of the essence in preventing extinction, to what extent should genetic and geographical distances be taken into account in deciding the most urgently needed conservation interventions? We propose that the populations of Sumatra and Borneo be considered as a single management unit.

Until the early 1980s the only surviving population of the greater one-horned rhinoceros Rhinoceros unicornis in Nepal was in Chitwan National Park. Between 1986 and 2003 87 rhinoceroses from Chitwan were translocated into Bardia National Park and Suklaphanta Wildlife Reserve in the western terai region to establish founder populations and reduce the threat of local extinction from natural catastrophic events, disease and/or poaching. The founder populations increased in number through births but a rise in poaching during the period of civil strife in Nepal during 1996–2006 resulted in a dramatic decline in the populations, including in Chitwan. In 2001 the Terai Arc Landscape programme was initiated to connect 11 protected areas in Nepal and north-west India and facilitate dispersal of megafauna and manage them as metapopulations. Corridors that were restored under the programme and that connect Bardia and Suklaphanta with protected areas in India are now used by the greater one-horned rhinoceros. The successes and failures of the last 2 decades indicate that new paradigms for protecting rhinoceroses within and outside protected areas are needed, especially with reference to managing this species at a landscape scale.

We assessed the abundance and distribution of the greater one-horned or Indian rhinoceros Rhinoceros unicornis in all its potential habitats in Nepal, using block counts. In April 2011 5,497 km were searched in 3,548 elephant-hours over 23 days. The validity of the block count was assessed by comparing it with counts obtained from long-term monitoring using photographic identification of individual rhinoceroses (ID-based), and estimates obtained by closed population sighting–mark–resighting in the 214 km2 of Chitwan National Park. A total of 534 rhinoceroses were found during the census, with 503 in Chitwan National Park (density 1 km−2), 24 in Bardia National Park (0.28 km−2) and seven in Suklaphanta Wildlife Reserve (0.1 km−2). In Chitwan 66% were adults, 12% subadults and 22% calves, with a female : male ratio of 1.24. The population estimate from sighting–mark–resighting was 72 (95% CI 71–78). The model with different detection probabilities for males and females had better support than the null model. In the Sauraha area of Chitwan estimates of the population obtained by block count (77) and ID-based monitoring (72) were within the 95% confidence interval of the estimate from sighting–mark–resighting. We recommend a country-wide block count for rhinoceroses every 3 years and annual ID-based monitoring in a sighting–mark–resighting framework within selected subpopulations. The sighting–mark–resighting technique provides the statistical rigour required for population estimates of the rhinoceros in Nepal and elsewhere.

As part of a census of the Indian rhinoceros Rhinoceros unicornis a survey was conducted to measure the extent of invasion by the neotropical plant mikania Mikania micrantha across major habitats of Chitwan National Park important for the conservation of the rhinoceros. Previous work has demonstrated that this fire-adapted plant can smother and kill native flora such as grasses and sapling trees, several of which are important fodder plants of the rhinoceros. Here, additional studies were conducted on the risks of anthropogenic factors (natural resource collection and grassland burning) contributing to the spread and growth of the plant. Mikania is currently found across 44% of habitats sampled and almost 15% of these have a high infestation (> 50% coverage). Highest densities were recorded from riverine forest, tall grass and wetland habitats and this is where the highest numbers of rhinoceroses were recorded in the habitats surveyed during the census. Local community dependence on natural resources in the core area of the Park is high. The range and volume of resources (e.g. fodder) collected and the distances travelled all pose a high risk of the spread of mikania. Of greater significance is the annual burning of the grasslands in the Park by local communities, estimated at 25–50% of the total area. It is imperative, therefore, that core elements of a management plan for mikania incorporate actions to control burning, reduce spread and raise awareness about best practice for local resource management by local communities.

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.

Amid declining shark populations because of overfishing, a burgeoning shark watching industry, already well established in some locations, generates benefits from shark protection. We compile reported economic benefits at shark watching locations and use a meta-analytical approach to estimate benefits at sites without available data. Results suggest that, globally, c. 590,000 shark watchers expend > USD 314 million per year, directly supporting 10,000 jobs. By comparison, the landed value of global shark fisheries is currently c. USD 630 million and has been in decline for most of the past decade. Based on current observed trends, numbers of shark watchers could more than double within the next 20 years, generating > USD 780 million in tourist expenditures around the world. This supports optimistic projections at new sites, including those in an increasing number of shark sanctuaries established primarily for shark conservation and enacted in recognition of the ecological and economic importance of living sharks.

Hunting is a serious threat to Indian wildlife. We used semi-structured interviews to assess hunting practices, cultural contexts and village-level governance within a Buddhist Indo-Tibetan tribe in the biologically rich region of Arunachal Pradesh. A large majority (96%) of the 50 respondents preferred wild meat over domestic meat, and most hunted for recreation. Species such as the Asian elephant Elephas maximus are still considered taboo to hunters but other species that were once taboo (such as gaur Bos gaurus) are now hunted. A month-long ban was previously instituted to prohibit tribal hunting during the wildlife breeding season each year but this has now decreased to 16-days duration. A multi-level governance framework is needed to resolve a mismatch between national policy in India and grass-roots governance for managing wildlife hunting.