Sustainable hunting could offer valuable lessons in managing the threat of biodiversity loss to hunting pressure across the tropics, according to research from Newcastle University.
A recent study offers evidence that hunting in Manu National Park, Peru – if implemented at low levels of pressure – can be done without substantially impacting local forest biodiversity.
Contents
- What is the Neotropics?
- The ‘empty forest’ effect
- Subsistence vs unsustainable hunting
- Results of the study
- Implications for management and next steps
- About the author
What is the Neotropics?
The Neotropics is one of eight biogeographic regions that make up the earth's land surface. It encompasses South America, Central America, southern North America, and the Caribbean Islands, and contains more tropical rainforest than any other area.
Led by Jennifer McFarlane, a postgraduate researcher from the School of Natural and Environmental Sciences, the study examined the reality of hunting in neotropical forests, and how it can be managed to reduce the threat to biodiversity.
The ‘empty forest’ effect
Subsistence hunting has occurred across the tropics for over 100,000 years and plays an important role for food security, livelihoods, and rights of subsistence hunters who have little alternative access to protein.
However, in recent decades, growing human populations – coupled with increased accessibility to forests and commercialisation of wild meat for urban markets – have rapidly increased the demand for wild meat across the tropics. As a result, perceived ‘healthy’ forests are structurally intact, yet void of wildlife, creating the ‘empty forest’ effect1.
The impact on biodiversity depends on a species' vulnerability to extinction, which is determined by their life history attributes (including body size and diet). Large-sized mammals such as herbivores usually have a higher preference among hunters, and due to their long generation lengths and low reproductive rates, they are typically the first to see their numbers drop. Meanwhile, large carnivores – which have often been ignored by hunting impact surveys – have suffered severe declines both directly from retaliation killings and trade, and indirectly from the loss of prey caused by hunters.
A female jaguar and her cubs, as caught on the team's trail cam. Video: Jennifer McFarlane.
Subsistence vs unsustainable hunting
Unsustainable hunting first appeared in several regions in Asia where more efficient shotguns are used widely, forests are highly accessible due to extensive habitat loss, and hunting activities have strong ties to large-scale wildlife trade.
In the Neotropics, 52% of the Amazon basin is covered by indigenous reserves where human population density remains low. Manu National Park hosts the indigenous Matsigenka community, who live in the very remote core (‘untouchable zone’). By law, they must maintain traditional practices – such as hunting with the bow and arrow – to avoid interfering with the park’s conservation goals. Protected areas managed by Indigenous communities represent a great potential for protecting biodiversity whilst maintaining the rights and stewardship responsibilities of Indigenous people.
Hunting is thought to be mostly sustainable in Manu National Park, but up until now, evidence has been limited.
Results of the study
This study was a collaboration between Newcastle University, Frankfurt Zoological Society Perú, and San Diego Zoo Perú.
Researchers used camera traps along hunting pressure gradients at Matsigenka settlements and at Cocha Cashu Biological Research Station where no hunting takes place. They assessed habitat structure and landscape attributes that can affect mammal habitat use, and subsequently analysed images to study mammal communities and their variations across the survey points.
The results show that subsistence hunting pressure, while of low impact, selectively impacts some mammal species more than others.
Species that are larger and have fewer offspring were less abundant at sites with hunting compared to sites with no hunting, but they were still present at all sites. These are mostly carnivores, like jaguars and ocelots.
Smaller species with shorter generation lengths, and large litters were more abundant at hunted sites (mostly rodents such as agoutis and pacas), similar to findings in the Brazilian Amazon2 and across the tropics3.
‘Our findings suggest that hunting in Manu NP is mostly sustainable with only local depletion of a few sensitive species, complementing previous findings in the area’, says Jennifer. ‘But it also highlights the importance of surveying the whole mammal community when investigating hunting impacts. […] The data indicates that hunting may pose a small threat to carnivore populations within the park and may have altered the way carnivores use the landscape, in particular near settlements of local indigenous Matsigenka. Also, the hunting efficiency of the bow and arrow technique is low, causing little depletion compared to shotguns which have caused unsustainable extraction rates in other areas of the Amazon’.
The study also tested for the effects of changes in forest habitat attributes on the mammal species. Tapirs, collared peccaries, and other herbivores are the second most hunted group after primates for the Matsigenka. However, their abundance in the forests was unaffected by hunting. Collared peccaries had higher abundances in denser vegetation areas close to lakes, and tapirs were at higher abundances at close distances to rivers. Peccaries use lakes and flooded areas for wallowing, and tapir habitat use is strongly associated with rivers where they forage, rest, and move between feeding sites.
Dr Marion Pfeifer, Professor in Forest Landscape Restoration at the School of Natural and Environmental Sciences at Newcastle University, and co-author of the study says: ‘We have discussed the encouraging findings in the team. We believe they support the suggestion of previous work by Ohl-Schacherer et al. 20074 that the low human population density of local communities and their relatively small hunting catchments (< 10 km) leave large areas of forest undisturbed by humans. This allows mammals to migrate from untouched forest to the hunted forest areas, replacing individuals lost to hunting.’
Implications for management and next steps
The work implies that community-managed hunting quotas may be helpful to some extent recognising that observed hunting impacts are low.
If quotas are developed, these should be focussed on maintaining reliable levels of carnivore prey species, mitigating larger - albeit indirect - impacts of hunting on carnivores. However, such quotas would require more research and need to be acceptable not only within the national park’s management framework but also designed with community cultural norms and indigenous rights in mind.
Jennifer emphasises that the rights and needs of local communities will need to be at the forefront of any changes in the management of local resources. ‘The Matsigenka at Manu National Park have shown us that hunting can be sustainable if traditional hunting techniques are maintained and may provide an example of mitigating impacts of hunting to other areas across the tropics.’
About the author
Jennifer is continuing her research and will start her PhD at Newcastle University in autumn 2024, funded by the IAPETUS2 Doctoral Training Partnership. She will be joining the TROPical landScapes lab, which has been studying mammal responses to hunting and habitat quality changes in Brunei Darussalam and Sarawak, Malaysian Borneo.
You might also like
- read the study: McFarlane, J. J., Chacón, O. M., Arauco-Aliaga, R. P., Braunholtz, L., Sanderson, R., & Pfeifer, M. (2024). Selective impacts of subsistence hunting on mammal communities in Manu National Park, Peru. Biotropica, 00, e13367. https://doi.org/10.1111/btp.13367
- explore more research from our School of Natural and Environmental Sciences
- learn more about the researchers involved in this study:
- Jennifer McFarlane, postgraduate researcher
- Dr Marion Pfeifer, Associate Professor, Landscape Ecology and Management
References:
1 Redford, K. H. (1992). The empty Forest. Bioscience, 42(6), 412–422. https://doi.org/10.2307/1311860
2 Peres, C. A. (2000). Effects of subsistence hunting on vertebrate community structure in Amazonian forests. Conservation Biology, 14(1), 240–253. https://doi.org/10.1046/j.1523-1739.2000.98485.x
3 Benítez-López, A., Alkemade, R., Schipper, A. M., Ingram, D. J., Verweij, P. A., Eikelboom, J. A. J., & Huijbregts, M. A. J. (2017). The impact of hunting on tropical mammal and bird populations. Science, 356(6334), 180–183. https://doi.org/10.1126/science.aaj1891
4 OHL-SCHACHERER, J., SHEPARD, G.H., Jr, KAPLAN, H., PERES, C.A., LEVI, T. and YU, D.W. (2007), The Sustainability of Subsistence Hunting by Matsigenka Native Communities in Manu National Park, Peru. Conservation Biology, 21: 1174-1185. https://doi.org/10.1111/j.1523-1739.2007.00759.x