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.

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.

Concerns regarding the sustainability of the seahorse Hippocampus spp. trade led to their listing on CITES Appendix II in 2002, with implementation in 2004. In 2007 we interviewed wholesale traders of seahorses in Hong Kong, China, seeking indications of the effects of the CITES listing on the seahorse trade. We cross-validated traders’ perspectives with government trade statistics (1998–2007) from Hong Kong and Taiwan. We also compared these data with trade statistics for pipefish, which are related species with similar medicinal uses but are not CITES-listed. Both the interviews and government statistics indicated reduced volumes of seahorses traded through Hong Kong, changes in source countries, and price increases post-implementation. Traders suggested that these changes were largely a result of the CITES listing. However, data indicate that other factors such as shifts in domestic policies and local demand may also have affected the trade. By cross-validating the perspectives of local stakeholders with trade statistics in a wildlife trading hub we were able to explore hypotheses on the local and global impacts of CITES. Such approaches are especially important for CITES-listed species because often there is no single data source that is complete and wholly reliable.

Research has shown that consumers of wildlife are price sensitive and that the quantity of meat purchased is influenced by the cost of bushmeat and its substitutes. Although there is evidence that hunter-gatherers are optimal foragers whose behaviour is influenced by costs associated with foraging, there is a paucity of studies on whether the behaviour of bushmeat hunters, like that of consumers, is cost sensitive. This paper reports data on the practices of indigenous bushmeat hunters in the lowland forests of Ecuador before and after a national tax on firearms and ammunition was increased by 300%. Results show that hunters' behaviour is, as predicted by optimal foraging theory, responsive to price signals. After a substantial increase in the national tax on shotgun cartridges, hunters modified the set of species considered worth hunting, dropping smaller-bodied species from the set of species they target during a hunt and switching the technology used for hunting, increasingly using muzzle loader shotguns and thus avoiding the cost of expensive cartridges.

Subsistence hunting can change the demographic structure of wild mammal populations, increasing the proportion of young animals, inducing females to reproduce early and increasing litter sizes. We examined the relationship between hunting pressure and age structure in the Vulnerable white-lipped peccary Tayassu pecari, analysing the distribution of age classes at seven sites in the region Terra do Meio in the Brazilian Amazon. These sites differ in the number of human inhabitants and hence were subject to differing hunting pressures. We completed semi-structured interviews with local people to assess the importance of hunting and of the white-lipped peccary as food. We also estimated the age of hunted white-lipped peccaries by assessing tooth eruption and tooth wear in skulls of hunted individuals. Our results indicated that the white-lipped peccary was the most frequently hunted terrestrial animal in the region. Fishing, followed by hunting, provided the main sources of animal protein. Our data suggest there is no relationship between age structure and hunting at the study sites. The social structure and mobility of white-lipped peccaries seem to minimize the effects of hunting on age structure. Our results, similar to previous studies, show that the age structure of the white-lipped peccary is robust to hunting impacts. Other factors may have stronger effects on age structure than subsistence hunting. We suggest that deforestation may explain the prevalence of older individuals in peccary populations to the north of our study sites.

Millions of people throughout the tropics consume wild meat. Overhunting reduces food security for people and large predators, yet little is known of the impact of hunting in systems where people and predators target the same prey species. We collate published data on predator diet in Belize with interview data about the consumption of wild and domestic meat by Belizeans, to compare the wild-meat diets of humans, jaguars Panthera onca and pumas Puma concolor and assess the sustainability of the combined offtake by humans and jaguars. Six wild mammal species (nine-banded armadillo Dasypus novemcinctus, paca Cuniculus paca, collared peccary Pecari tajacu, white-lipped peccary Tayassu pecari, red brocket deer Mazama americana and white-tailed deer Odocoileus virginianus) comprised 7% of the animal-protein meals eaten by Belizeans. Overall, 80% of these meals were eaten by 20% of interviewees, suggesting a necessary role of wild meat for the minority. The same species were found in 69 and 86% of jaguar and puma scats, respectively. We estimate a national annual harvest of c. 4,000 tonnes of these six wild mammals by humans and jaguars, of which 78% is hunted by people. Sustainability is difficult to evaluate because prey population data are lacking in Belize. However, simple models suggest that a sustainable harvest at this rate would require higher prey population densities than averages recorded in hunted Neotropical forests. We emphasize the need for robust regional estimates of game species densities, to improve assessments of sustainability and inform hunting regulations. We recommend that the requirements of predators as well as those of people be considered when assessing wild meat harvests.

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.

Bushmeat trade is a threat to biodiversity in Africa. Information about the bushmeat value chain can inform conservation policies, yet such knowledge is lacking for most of East Africa. We examine the structure and organization of bushmeat markets in three villages in the Kilombero Valley of Tanzania, where illegal hunting is widespread. We base our analysis on 1,855 observations of trade during 1 year (2008–2009) and questionnaire interviews with 325 individuals involved in the trade in 2011. Our results reveal that the trade is large-scale both in volume (1,100 animals, equivalent to 370,000 kg meat per year) and local turnover (USD 210,000 per year) and that several threatened species are hunted. There are no patron–client relationships and hunters, traders and retailers, which are the main actors involved, conduct only basic product upgrading (drying and making packages). The value chain is characterized by governance problems, including widespread rent-seeking and violent enforcement. Although hunting is open-access, lack of access to firearms constitutes an entry barrier, curbing supply and enabling actors to realize supernormal profits. Decentralization of management rights and responsibilities to communities, supplemented by improved firearms control, appears the most realistic option for regulating the trade and preventing further declines of wildlife.

Trends in the populations of large herbivores in Niassa Reserve, Mozambique, have been monitored through biennial aerial surveys since 1998. The elephant Loxodonta africana population has been subjected to intensive illegal hunting since 2006. We used a simple population model to mimic the observed trends in the numbers of live and dead elephants to demonstrate the impact of poaching. The number of fresh or recent carcasses recorded was used in the model as an index of the annual mortality rate. A maximum likelihood analysis to compare population models revealed that the best fit to the survey estimates of both live elephants and old or very old carcasses was a model that started with 6,635 elephants in 1987. This number increased through births by 4.6% annually and decreased through deaths from natural and anthropogenic causes. In the best-fit model, the mean mortality rate in any year was 3.2 times the observed 1 + 2 carcass ratio (ratio for carcasses in age categories 1 and 2), and carcasses remained visible for a mean of 6 years. The model suggested that c. 900 elephants were poached during 2007–2010 and another c. 1,000 during 2011. Population estimates for live elephants and carcasses are now routine outcomes of aerial surveys conducted as part of the CITES programme for Monitoring the Illegal Killing of Elephants, and our method can be applied to any population with a time series of estimates for live and dead elephants.

The collapse of South Asia's Gyps vulture populations is attributable to the veterinary use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac. Vultures died after feeding on carcasses of recently-medicated animals. The governments of India, Nepal and Pakistan banned the veterinary use of diclofenac in 2006. We analysed results of 62 necropsies and 48 NSAID assays of liver and/or kidney for vultures of five species found dead in India between 2000 and 2012. Visceral gout and diclofenac were detected in vultures from nine states and three species: Gyps bengalensis, Gyps indicus and Gyps himalayensis. Visceral gout was found in every vulture carcass in which a measurable level of diclofenac was detected. Meloxicam, an NSAID of low toxicity to vultures, was found in two vultures and nimesulide in five vultures. Nimesulide at elevated tissue concentrations was associated with visceral gout in four of these cases, always without diclofenac, suggesting that nimesulide may have similar toxic effects to those of diclofenac. Residues of meloxicam on its own were never associated with visceral gout. The proportion of Gyps vultures found dead in the wild in India with measurable levels of diclofenac in their tissues showed a modest and non-significant decline since the ban on the veterinary use of diclofenac. The prevalence of visceral gout declined less, probably because some cases of visceral gout from 2008 onwards were associated with nimesulide rather than diclofenac. Veterinary use of nimesulide is a potential threat to the recovery of vulture populations.

Monitoring of wild populations is central to species conservation and can pose a number of challenges. To identify trends in populations of parrots, monitoring programmes that explicitly take detectability into account are needed. We assessed an occupancy model that explicitly accounted for detectability as a tool for monitoring the large macaws of Bolivia's Beni savannahs: the blue-throated Ara glaucogularis, blue-and-yellow Ara ararauna and red-and-green macaws Ara chloropterus. We also evaluated the joint presence of the three macaw species and estimated their abundance in occupied areas. We modelled occupancy and detection for the three macaw species by combining several site and visit covariates and we described their conditional occupancy. Macaws occupied two thirds of the surveyed area and at least two species occurred together in one third of this area. Probability of detection was 0.48–0.86. For each macaw species, occupancy was affected by the abundance of the other two species, the richness of cavity-nesting species, and the distance to the nearest village. We identified key priority areas for the conservation of these macaws. The flexibility of occupancy methods provides an efficient tool for monitoring macaw occupancy at the landscape level, facilitating prediction of the range of macaw species at a large number of sites, with relatively little effort. This technique could be used in other regions in which the monitoring of threatened parrot populations requires innovative approaches.