Measuring local depletion of terrestrial game vertebrates by central-place hunters in rural Amazonia

The degree to which terrestrial vertebrate populations are depleted in tropical forests occupied by human communities has been the subject of an intense polarising debate that has important conservation implications. Conservation ecologists and practitioners are divided over the extent to which community-based subsistence offtake is compatible with ecologically functional populations of tropical forest game species. To quantify depletion envelopes of forest vertebrates around human communities, we deployed a total of 383 camera trap stations and 78 quantitative interviews to survey the peri-community areas controlled by 60 semi-subsistence communities over a combined area of over 3.2 million hectares in the Médio Juruá and Uatumã regions of Central-Western Brazilian Amazonia. Our results largely conform with prior evidence that hunting large-bodied vertebrates reduces wildlife populations near settlements, such that they are only found at a distance to settlements where they are hunted less frequently. Camera trap data suggest that a select few harvest-sensitive species, including lowland tapir, are either repelled or depleted by human communities. Nocturnal and cathemeral species were detected relatively more frequently in disturbed areas close to communities, but individual species did not necessarily shift their activity patterns. Group biomass of all species was depressed in the wider neighbourhood of urban areas rather than communities. Interview data suggest that species traits, especially group size and body mass, mediate these relationships. Large-bodied, large-group-living species are detected farther from communities as reported by experienced informants. Long-established communities in our study regions have not “emptied” the surrounding forest. Low human population density and low hunting offtake due to abundant sources of alternative aquatic protein, suggest that these communities represent a best-case scenario for sustainable hunting of wildlife for food, thereby providing a conservative assessment of game depletion. Given this ‘best-case’ camera trap and interview-based evidence for hunting depletion, regions with higher human population densities, external trade in wildlife and limited access to alternative protein will likely exhibit more severe depletion

Trouble in Paradise: Indigenous Populations, Anthropological Policies, and Biodiversity Conservation in Manu National Park, Peru

Manu National Park was founded in 1973 on a profound contradiction: The “untouchable” core area is, in fact, the homeland of a large indigenous population, including the Matsigenka (Machiguenga). Some view the Westernization of native communities living in protected areas as a threat to biodiversity conservation and suggest that such populations should be enticed to resettle outside parks. Here, we present an overview of the indigenous populations of Manu, outline the history of the park and its anthropological policies, and discuss evolving park-Matsigenka conflicts as well as areas of common interest. Analysis reveals that resettlement has no political, legal, or practical viability. Thus, given the options available, we propose that long-term biodiversity conservation can best be achieved through a “tenure for defense” trade: indigenous communities receive explicit benefits (e.g., infrastructure and service investments, employment opportunities, or economic alternatives such as ecotourism) in exchange for helping to defend the park against incursion and managing vulnerable resources such as game animals

Modelling the long-term sustainability of indigenous hunting in Manu National Park, Peru: Landscape-scale management implications for Amazonia

1. Widespread hunting throughout Amazonia threatens the persistence of large primates and other vertebrates. Most studies have used models of limited validity and restricted spatial and temporal scales to assess the sustainability. 2. We use human-demographic, game-harvest and game-census data to parameterize a spatially explicit hunting model. We explore how population growth and spread, hunting technology and effort, and source–sink dynamics impact the density of black spider monkeys Ateles chamek over time and space in the rainforests of south-eastern Peru. 3. In all scenarios, spider monkey populations, which are vulnerable to hunting, persist in high numbers in much of Manu National Park over the next 50 years. Nonetheless, shotguns cause much more depletion than traditional bow hunting by Matsigenka (Machiguenga) indigenous people. 4. Maintenance of the current indigenous lifestyle (dispersed settlements, bow hunting) is unlikely to deplete spider monkeys and, by extension, other fauna, despite rapid human population growth. This helps explain why large, pre-Colombian human populations did not drive large primates to extinction. When guns are used, however, spider monkeys quickly become depleted around even small settlements, with depletion eventually reversing the short-term harvest advantage provided by shotgun hunting. Thus, our models show that when guns are used, limits on settlement numbers can reduce total depletion. 5. Synthesis and applications. Our framework lets us visualize the future effects of hunting, population growth, hunting technology and settlement spread in tropical forests. In Manu Park, the continued prohibition of firearms is important for ensuring long-term hunting sustainability. A complementary policy is to negotiate limits on new settlements in return for development aid in existing settlements. The advantage of the latter approach is that settlement numbers are more easily monitored than is hunting effort or technology. Similar policies could help to reduce landscape-scale depletion of prey species in human-occupied reserves and protected areas throughout the Amazon

Spatial tools for assessing the sustainability of subsistence hunting in tropical forests

Subsistence hunting provides a crucial food source for rural populations in tropical forests but is often practiced unsustainably. We use the empirical observation that subsistence hunters are central-place foragers to develop three 'biodemographic' hunting models of increasing complexity and realism for assessing the sustainability of hunting of an indicator species. In all our models, we calculate the spatial pattern of depletion of an indicator species (here, a large-bodied primate) across a landscape. Specifically, we show how to identify the area surrounding a human settlement that is expected to suffer local extinction. Our approach is an improvement over well-known sustainability indices of hunting, which are error-prone and do not provide clear links to policy prescriptions. Our first approach models the long-term effect of a single settlement and (1) can be parameterized with easily obtainable field data (such as settlement maps and knowledge of the major weapon used), (2) is simple enough to be used without requiring technical skill, and (3) reveals the asymptotic relationship between local human density and the level of game depletion. Our second model allows multiple settlements with overlapping hunting zones over large spatial scales. Our third model additionally allows temporal changes in human population size and distribution and source-sink dynamics in game populations. Using transect and hunting data from two Amazonian sites, we show that the models accurately predict the spatial distribution of primate depletion. To make these methods accessible, we provide software-based tools, including a toolbox for ArcGIS, to assist in managing and mapping the spatial extent of hunting. The proposed application of our models is to allow the quantitative assessment of settlement-stabilization approaches to managing hunting in Amazonia

Supplement 1. Model implementation with Excel spreadsheet, Matlab, and Python script for ArcGIS.

<h2>File List</h2><blockquote> <a href="analytical_spreadsheet_solver.xls">analytical_spreadsheet_solver.xls</a>*<br> <a href="multisettlement_model_solver.m">multisettlement_model_solver.m</a><br> <a href="Hunting_Mapper.zip">Hunting_Mapper.zip</a> - contains: <blockquote> - <a href="Hunting Mapper.tbx">Hunting Mapper.tbx</a><br> - <a href="monkeyscriptSteadyState.py">monkeyscriptSteadyState.py</a><br> - <a href="monkeyscript.py">monkeyscript.py</a> </blockquote> </blockquote><h2>Description</h2><blockquote> <p>analytical_spreadsheet_solver.xls* implements the simplest single settlement model in Microsoft Excel. It is designed to be easy to use on a platform familiar to non-technical users.</p> <p>multisettlement_model_solver.m is commented Matlab Code to produce multisettlement maps, cumulative distribution functions, and calculate the global and local catch per unit effort.</p> <p>Hunting_Mapper.zip is a zip file containing ArcGIS toolbox extension and the required python scriptsWindows executable. The toolbox is called, Hunting Mapper.tbx, and it can call two scripts. One script, monkeyscriptSteadyState.py, implements the multisettlement steady state model, which makes it suitable for large spatial and temporal scales. The other script, monkeyscript.py, implements the numerical multisettlement model with diffusive source-sink dynamics. This model is computationally expensive, and it requires the user to input the annual population data for evey settlement. See <a href="appendix-E.htm">Appendix E</a> for further instructions.</p> <p>* <i>Please note</i>: ESA cannot guarantee the accessibility of Excel files into the future due to the proprietary nature of the Excel format.</p> </blockquote

Appendix A. Calculating the game encounter rate e from line-transect data.

Calculating the game encounter rate e from line-transect data

Appendix F. How sustainability indices work and why we need better methods.

How sustainability indices work and why we need better methods

Appendix B. Equations for rmax(θ), rmin(θ), θmax, and θmin.

Equations for rmax(θ), rmin(θ), θmax, and θmin