Searching for sustainability: are assessments of wildlife harvests behind the times?

Wild meat: a shared resource amongst people and predators

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, jaguarsPanthera oncaand pumasPuma concolorand assess the sustainability of the combined offtake by humans and jaguars. Six wild mammal species (nine-banded armadilloDasypus novemcinctus, pacaCuniculus paca, collared peccaryPecari tajacu, white-lipped peccaryTayassu pecari, red brocket deerMazama americanaand white-tailed deerOdocoileus 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.

Illegal killing for ivory drives global decline in African elephants

Illegal wildlife trade has reached alarming levels globally, extirpating populations of commercially valuable species. As a driver of biodiversity loss, quantifying illegal harvest is essential for conservation and sociopolitical affairs but notoriously difficult. Here we combine field-based carcass monitoring with fine-scale demographic data from an intensively studied wild African elephant population in Samburu, Kenya, to partition mortality into natural and illegal causes. We then expand our analytical framework to model illegal killing rates and population trends of elephants at regional and continental scales using carcass data collected by a Convention on International Trade in Endangered Species program. At the intensively monitored site, illegal killing increased markedly after 2008 and was correlated strongly with the local black market ivory price and increased seizures of ivory destined for China. More broadly, results from application to continental data indicated illegal killing levels were unsustainable for the species between 2010 and 2012, peaking to ∼ 8% in 2011 which extrapolates to ∼ 40,000 elephants illegally killed and a probable species reduction of ∼ 3% that year. Preliminary data from 2013 indicate overharvesting continued. In contrast to the rest of Africa, our analysis corroborates that Central African forest elephants experienced decline throughout the last decade. These results provide the most comprehensive assessment of illegal ivory harvest to date and confirm that current ivory consumption is not sustainable. Further, our approach provides a powerful basis to determine cryptic mortality and gain understanding of the demography of at-risk species.

A review and synthesis of late Pleistocene extinction modeling: progress delayed by mismatches between ecological realism, interpretation, and methodological transparency

Late Pleistocene extinctions occurred globally over a period of about 50,000 years, primarily affecting mammals of > or = 44 kg body mass (i.e., megafauna) first in Australia, continuing in Eurasia and, finally, in the Americas. Polarized debate about the cause(s) of the extinctions centers on the role of climate change and anthropogenic factors (especially hunting). Since the late 1960s, investigators have developed mathematical models to simulate the ecological interactions that might have contributed to the extinctions. Here, we provide an overview of the various methodologies used and conclusions reached in the modeling literature, addressing both the strengths and weaknesses of modeling as an explanatory tool. Although late Pleistocene extinction models now provide a solid foundation for viable future work, we conclude, first, that single models offer less compelling support for their respective explanatory hypotheses than many realize; second, that disparities in methodology (both in terms of model parameterization and design) prevent meaningful comparison between models and, more generally, progress from model to model in increasing our understanding of these extinctions; and third, that recent models have been presented and possibly developed without sufficient regard for the transparency of design that facilitates scientific progress.

Conservation status of chimpanzees Pan troglodytes verus and other large mammals in Liberia: a nationwide survey

Liberia has the largest blocks of continuous forest in West Africa, providing habitat for numerous wildlife species. However, there is a lack of empirical data about the status of Liberia's wildlife populations. During 2010–2012 we conducted the first nationwide survey in Liberia along c. 320 km of systematically located transect lines to estimate the abundance of chimpanzees Pan troglodytes verus, the diversity of large mammals and the nature and degree of anthropogenic threats. With > 7,000 chimpanzees, Liberia is home to the second largest population of West African chimpanzees and is therefore a priority for conservation of the species. Compared to the fragmented populations in other range countries the Liberian population is potentially one of the most viable. Our study revealed that the majority of chimpanzees and some of the most species-diverse mammal communities in Liberia exist outside protected areas. High hunting rates and plans for large-scale exploitation of natural resources necessitate rapid implementation of effective strategies to ensure the protection of one of West Africa's last strongholds for chimpanzees and other rare and threatened mammal species. We provide a country-wide baseline dataset that may serve as a platform for Liberian wildlife authorities, policy-makers and international conservation agencies to make informed decisions about the location and delineation of proposed protected areas, to identify conservation gaps and to devise a conservation action plan to conserve Liberia's wildlife resources.

Synchrony in hunting bags: reaction on climatic and human induced changes?

Human induced land use changes negatively impact the viability of many wildlife species through habitat modifications and mortality, while some species seem to benefit from it. Roe deer (Capreolus capreolus), a wide spread ungulate increased both its abundance and range throughout Europe. This pattern is also reflected in the increasing hunting bags over the last 40 years. Such a development raises questions about the relationship between human hunting and population dynamics and, in particular, about the potential of human hunting to control related populations. We analysed and reconstructed annual hunting bags of roe deer for three federal states of northern Germany, Brandenburg, Lower Saxony and Mecklenburg West Pomerania for the years 1972 to 2011. Since 1992 the hunting bags from these three states are significantly higher than those reported for the years 1972-1991. Our reconstruction takes into consideration effects of climate variability, expressed by inter-annual changes in the North Atlantic Oscillation and impacts from rapeseed and wheat cultivation. We found that severe winters, which are indicated by negative values of the North Atlantic Oscillation during the months December-March, directly, or with a time lag of two years affect the number of deer shot. In contrast, an increase in the area used for rapeseed cultivation coincides with higher numbers of roe deer shot, with respect to the overall mean value. Consequently, we recommend that wildlife management addresses changes in large scale processes including land use pattern and climate variability.

Extent and ecological consequences of hunting in Central African rainforests in the twenty-first century

Humans have hunted wildlife in Central Africa for millennia. Today, however, many species are being rapidly extirpated and sanctuaries for wildlife are dwindling. Almost all Central Africa's forests are now accessible to hunters. Drastic declines of large mammals have been caused in the past 20 years by the commercial trade for meat or ivory. We review a growing body of empirical data which shows that trophic webs are significantly disrupted in the region, with knock-on effects for other ecological functions, including seed dispersal and forest regeneration. Plausible scenarios for land-use change indicate that increasing extraction pressure on Central African forests is likely to usher in new worker populations and to intensify the hunting impacts and trophic cascade disruption already in progress, unless serious efforts are made for hunting regulation. The profound ecological changes initiated by hunting will not mitigate and may even exacerbate the predicted effects of climate change for the region. We hypothesize that, in the near future, the trophic changes brought about by hunting will have a larger and more rapid impact on Central African rainforest structure and function than the direct impacts of climate change on the vegetation. Immediate hunting regulation is vital for the survival of the Central African rainforest ecosystem.