Illegal exploitation of resources is a cause of environmental degradation worldwide. The effectiveness of conservation initiatives such as marine protected areas relies on users' compliance with regulations. Although compliance can be motivated by social norms (e.g. peer pressure and legitimacy), some enforcement is commonly necessary. Enforcement is expensive, particularly in areas far from land, but costs can be reduced by optimizing enforcement. We present a case study of how enforcement could be optimized at Cocos Island National Park, Costa Rica, an offshore protected area and World Heritage Site. By analysing patrol records we determined the spatial and temporal distribution of illegal fishing and its relationship to patrol effort. Illegal fishing was concentrated on a seamount within the Park and peaked during the third year-quarter, probably as a result of oceanographic conditions. The lunar cycle in conjunction with the time of year significantly influenced the occurrence of incursions. The predictability of illegal fishing in space and time facilitates the optimization of patrol effort. Repeat offenders are common in the Park and we suggest that unenforced regulations and weak governance are partly to blame. We provide recommendations for efficient distribution of patrol effort in space and time, establishing adequate governance and policy, and designing marine protected areas to improve compliance. Our methods and recommendations are applicable to other protected areas and managed natural resources.

Biodiversity offsetting involves the balancing of biodiversity loss in one place (and at one time) by an equivalent biodiversity gain elsewhere (an outcome referred to as No Net Loss). The conservation science literature has chiefly addressed the extent to which biodiversity offsets can serve as a conservation tool, focusing on the technical challenges of its implementation. However, offsetting has more profound implications than this technical approach suggests. In this paper we introduce the concept of policy frames, and use it to identify four ways in which non-human nature and its conservation are reframed by offsetting. Firstly, offsetting reframes nature in terms of isolated biodiversity units that can be simply defined, measured and exchanged across time and space to achieve equivalence between ecological losses and gains. Secondly, it reframes biodiversity as lacking locational specificity, ignoring broader dimensions of place and deepening a nature–culture and nature–society divide. Thirdly, it reframes conservation as an exchange of credits implying that the value of non-human nature can be set by price. Fourthly, it ties conservation to land development and economic growth, foreshadowing and bypassing an oppositional position. We conclude that by presenting offsetting as a technical issue, the problem of biodiversity loss due to development is depoliticized. As a result the possibility of opposing and challenging environmental destruction is foreclosed, and a dystopian future of continued biodiversity loss is presented as the only alternative.

Despite the considerable expansion in the number and extent of marine protected areas during the past century, coverage remains limited amid concerns that many marine protected areas are failing to meet their objectives. New estimates of global marine protected area, based on the database maintained by Sea Around Us, revealed a degree of progress towards protecting at least 10% of the global ocean by 2020. It is estimated that > 6,000 marine protected areas, covering c. 3.27% (12 million km2) of the oceans, had been designated by the end of 2013. However, protection is generally weak, with c. one-sixth (1.9 million km2) of the combined area designated as no-take areas (i.e. fishing and other extractive activities are prohibited). Additional large tracts of ocean will need to be protected to reach the 10% target, and we investigate hypothetical scenarios for such expansion. Such scenarios offer a one-dimensional measure of progress as they do not address aspects of other global targets, such as Aichi Target 11, which will help to ensure that marine protected areas meet their objectives and achieve conservation outcomes.

The objectives of No Net Loss and Net Gain have emerged as key principles in conservation policy. Both give rise to mechanisms by which certain unavoidable biodiversity losses associated with development are quantified, and compensated with comparable gains (e.g. habitat restoration). The former seeks a neutral outcome for biodiversity after losses and gains are accounted for, and the latter seeks an improved outcome. Policy-makers often assume that the transition from one to the other is straightforward and essentially a question of the amount of compensation provided. Consequently, companies increasingly favour Net Gain type commitments, and financial institutions make lending conditional on either objective, depending on the habitat involved. We contend, however, that achieving Net Gain is fundamentally different to achieving No Net Loss, and moving from one to the other is less trivial than is widely realized. Our contention is based on four arguments: (1) the two principles represent different underlying conservation philosophies; (2) ecological uncertainties make it difficult to know where the threshold between No Net Loss and Net Gain lies; (3) different frames of reference are more or less appropriate in evaluating the ecological outcomes, depending on the principle chosen; and (4) stakeholder expectations differ considerably under the two principles. In exploring these arguments we hope to support policy-makers in choosing the more appropriate of the two objectives. We suggest that financial institutions should provide greater clarity regarding the explicit requirements for each principle. We conclude by highlighting questions of relevance to this topic that would benefit from focused research.

The commercial bushmeat trade threatens numerous species in the forests of West and Central Africa. Hunters shoot and trap animals, which are transported to rural and urban markets for sale. Village-based surveys of hunter offtake and surveys of bushmeat markets have shown that mammals and reptiles are affected most, followed by birds. However, hunters also consume some animals in forest camps and these may have been overlooked in surveys that have focused on bushmeat extracted from the forest. A number of studies have used indirect methods, such as hunter diaries, to quantify this additional offtake but results can be difficult to verify. We examined discarded animal remains at 13 semi-permanent hunting camps in the Ebo Forest, Cameroon, over 272 days. Twenty-one species were identified from 49 carcasses, of which birds constituted 55%, mammals 43% and other taxa 2%. The mammals identified were typical of those recorded in previous bushmeat studies but we recorded several species of birds rarely recorded elsewhere. Offtake of bird species increased with mean body mass. We extrapolated our results to the 34 known hunting camps in the Ebo Forest and estimated that a minimum of 97 birds are hunted annually in a catchment area of c. 479 km2. We conclude that some bird species may be hunted more frequently than previous research suggests and this has important conservation implications for larger-bodied species such as raptors and hornbills.

The ecology and predator–prey dynamics of large felids in the tropics have largely been studied in natural systems where wild ungulates constitute the majority of the prey base. However, human-dominated landscapes can be rich in potential prey for large carnivores because of the high density of domestic animals, especially in tropical countries where pastoralism is an important livelihood activity. We report the almost complete dependence of leopards Panthera pardus on domestic animals as prey in the crop lands of Ahmednagar district, Maharashtra, India. From analysis of 85 confirmed leopard scats, 87% of the leopard's prey biomass consisted of domestic animals, with 39% consisting of domestic dogs Canis lupus familiaris alone. The only wild species that occurred in the leopard's diet were rodents, small indian civet Viverricula indica, bonnet macaque Macaca radiata and other primates Semnopithecus spp., mongoose Herpestes spp., and birds. Interviews conducted in 77 households distributed randomly in the study area documented a high density of domestic animals: adult cattle Bos taurus, calves, goats Capra aegagrus, dogs and cats Felis catus occurred at densities of 169, 54, 174, 24 and 61 per km2, respectively. Ivlev's electivity index indicated that dogs and cats were over-represented in the leopard's diet, given the higher densities of goats and cattle. The standing biomass of dogs and cats alone was sufficient to sustain the high density of carnivores at the study site. Our results show that the abundance of potential domestic prey biomass present in human-use areas supports a relatively high density of predators, although this interaction could result in conflict with humans.

We question whether the increasingly popular, radical idea of turning half the Earth into a network of protected areas is either feasible or just. We argue that this Half-Earth plan would have widespread negative consequences for human populations and would not meet its conservation objectives. It offers no agenda for managing biodiversity within a human half of Earth. We call instead for alternative radical action that is both more effective and more equitable, focused directly on the main drivers of biodiversity loss by shifting the global economy from its current foundation in growth while simultaneously redressing inequality.

The conservation of species listed in the Bern Convention and European Directive 1992/43/EEC (so-called policy species) is mandatory for European Union (EU) countries. We assessed the conservation status of Italian policy species, based on the IUCN categories and criteria, to evaluate the effectiveness of existing protection measures at the national level. Among the 203 vascular plants, bryophytes and lichens evaluated, 41.9% are categorized as threatened, and one is already extinct, indicating that the protection measures for policy species are inadequate. Our results for the Italian policy species are consistent with those of an assessment at the EU level. Conservation priorities should be established at both the national and regional scales. An effective conservation strategy is needed, and in situ and ex situ actions focused on threatened species should be promoted.

Four species of African vultures have been recategorized as Critically Endangered, and two as Endangered, on the IUCN Red List. Their declining status is attributed partly to the impacts of widespread poisoning. Prior to 2012 poisoning of vultures was mostly associated with illegal predator control by livestock farmers, in which vultures were typically unintended victims. More recently, ivory poachers have been using poisons to kill elephants Loxodonta africana or to contaminate their carcasses specifically to eliminate vultures, whose overhead circling might otherwise reveal the poachers’ presence. Between 2012 and 2014 we recorded 11 poaching-related incidents in seven African countries, in which 155 elephants and 2,044 vultures were killed. In at least two incidents the harvesting of vulture body parts (for fetish) may have provided an additional motive. We show that vulture mortality associated with ivory poaching has increased more rapidly than that associated with other poisoning incidents, and now accounts for one-third of all vulture poisonings recorded since 1970. This recent surge in the illegal use of poisons exposes weaknesses in the regulations, for which we propose measures aimed primarily at retail controls. However, because ivory poachers already operate outside any legal framework, African governments require international support in applying more punitive sentencing against mass wildlife poisoning.

Diurnal raptors have declined significantly in western Africa since the 1960s. To evaluate the impact of traditional medicine and bushmeat trade on raptors, we examined carcasses offered at markets at 67 sites (1–80 stands per site) in 12 countries in western Africa during 1990–2013. Black kite Milvus migrans and hooded vulture Necrosyrtes monachus together accounted for 41% of 2,646 carcasses comprising 52 species. Twenty-seven percent of carcasses were of species categorized as Near Threatened, Vulnerable or Endangered on the IUCN Red List. Common species were traded more frequently than rarer species, as were species with frequent scavenging behaviour (vs non-scavenging), generalist or savannah habitat use (vs forest), and an Afrotropical (vs Palearctic) breeding range. Large Afrotropical vultures were recorded in the highest absolute and relative numbers in Nigeria, whereas in Central Africa, palm-nut vultures Gypohierax angolensis were the most abundant vulture species. Estimates based on data extrapolation indicated that within West Africa 73% of carcasses were traded in Nigeria, 21% in Benin and 5% elsewhere. Offtake per annum in West Africa was estimated to be 975–1,462 hooded vultures, 356–534 palm-nut vultures, 188–282 Rüppell's griffons Gyps rueppellii, 154–231 African white-backed vultures Gyps africanus, 143–214 lappet-faced vultures Torgos tracheliotos, and 40–60 crowned eagles Stephanoaetus coronatus. This represents a sizeable proportion of regional populations, suggesting that trade is likely to be contributing significantly to declines. Stronger commitment is needed, especially by governments in Nigeria and Benin, to halt the trade in threatened raptors and prevent their extirpation.