Social-ecological modelling for improved sustainability of hunting
Nils Bunnefeld & E.J. Milner-Gulland
Making conservation decisions to benefit species, habitats and people is challenging due to the complexity and the limited knowledge that characterises interlinked social-ecological systems. We developed a new approach for modelling the sustainability of interventions in social-ecological systems that extends an existing framework from fisheries science and makes it more appropriate for situations with multiple interventions, multiple users and compliance challenges. This makes the framework more appropriate for many small-scale terrestrial systems in developing countries. This framework is easily integrated into adaptive management and very flexible.
Our approach can use qualitative and quantitative information by combining different data types (e.g. social data, economic data, ecological monitoring data, harvest data) and using the full extent of time series data effectively. We show the quality and quantity of monitoring data that is needed to make informed decisions and the robustness of the decision-making process to different types and degrees of uncertainty.
Incorporating human decision making in models of the dynamics of harvested systems allows us to consider transparently the tradeoffs of different conservation actions for different stakeholders and based on different performance metrics. More transparency has been shown to contribute to conflict resolution and builds trust between stakeholders who may have very different objectives.
Messages from the case studies
Theoretical modelling framework
A simulation model combining fisheries management approaches with household utility theory and two literature reviews identified that individual decision making affects the dynamics of natural resource use systems and its sustainability. It is thus crucial for the success of conservation to understand and take into account incentives of resource users to make recommendations for conservation 9-11.
Bears in Croatia/Slovenia
People respond to changes in the management of wildlife with changes in their attitudes towards these species, especially if they are hunted and cause conflicts; a more centralised bear management led to more support for limiting bear numbers but overall attitudes remained positive due to the bear's cultural importance, and associated use and bequest values8. Economic analysis of stakeholders for the same case study shows that joining the EU in 2013, which will stop trophy hunting, will result in economic losses for bear managers3. This suggests that hunting will not be economically viable and this might lead to lower compliance and thus higher poaching rates. The change from a hunted to a protected bear population might threaten a so far socially and ecologically sustainable hunting system.
In an MSc thesis, we revisited the habitat selection of brown bears in Slovenia and Croatia in relation to natural and human dominated features in the landscape. Proximity to supplemental feeding stations and availability of large forest patches (> 5000 hectares) were the best predictors of brown bear habitat selection13. Feeding stations are shared with red deer, another important species for hunting, but the future of these feeding stations is uncertain without income from brown bear trophy hunting. Without feeding stations, brown bear might roam more widely which might increase levels of conflicts with local people.
Mountain nyala in Ethiopia
The quality and quantity of information (e.g. monitoring) determines the ability to make informed decisions. Our case study on mountain nyala, an ungulate endemic to Ethiopia, showed that the 10 years of monitoring data currently available is sufficient to make informed decisions, but that the system is currently hampered by large uncertainties in the precision of monitoring and the unknown rate of population loss (e.g. poaching or habitat loss)1,5.
Bushmeat in Tanzania
In the case study on monitoring impala and wildebeest in the Serengeti, the spatial distribution (clumped vs even) and the monitoring effort have been show to interact to determine the bias and precision of the monitoring data. This approach is crucial when developing long term monitoring plans to manage wildlife4.
The extent of bushmeat hunting in Tanzania is largely uncertain. We used indirect questioning techniques to allow anonymity of the respondent. Among a range of techniques, the unmatched count technique was selected for clarity and ease of use above the 2-card, the randomized response and the ballot box technique after a pilot study. The estimated percentage of households engaged in bushmeat hunting was around 19% in the dry season and 13% in the wet season4.
Additional work - lion hunting
African lions have decreased over the last decade across Africa despite theory predicting that age limited trophy hunting could be sustainable. We developed a new model for sustainable trophy hunting that includes harvest rule that sets the maximum searching time until a kill and that is robust to a large range of uncertainties. This model that uses data that would be readily available for a range of trophy hunted species (time spent before an animal is killed) to develop simple yet robust rules for sustainable harvesting. Thus, this approach should be widely applicable.
To be submitted in next 2 months (manuscripts in final or near-final draft)
1. Bunnefeld N, Edwards CTT, Atickem A, Hailu F, Milner-Gulland EJ. Incentivising monitoring and compliance in mountain nyala trophy hunting: a Management Strategy Evaluation approach. Ecological Applications
2. Edwards CTT, Bunnefeld N, Balme G, Milner-Gulland EJ. Data-poor management of African lion hunting: how to set quotas when the population size is unknown. Science?
3. Knott E, Bunnefeld N, Huber D, Reljic S, Keresi V, Milner-Gulland EJ. Changes in hunting policy: who bears the cost? Environmental Conservation
4. Nuno A, Bunnefeld N, Milner-Gulland EJ. Monitoring uncertainty is affected by effort and spatial distribution: a case study of impala and wildebeest in the Serengeti. Journal of Applied Ecology.
Trophy hunting is a controversial conservation tool but one which has been successfully implemented in some situations where human-wildlife conflict has jeopardised the survival of the conflict species. The brown bear (Ursus arctos) in Croatia is currently being managed through quota-based trophy hunting. Human-bear conflict is present, but any losses are compensated by the hunting organisations who benefit from the bear hunting. Attitudes towards bears are generally positive and the bear population appears stable, or even increasing. Croatia's imminent accession to the EU will require changes in their bear management system. We quantified the costs and benefits of bear hunting to hunting organisations currently, and in the case of bear trophy hunting no longer being allowed. The costs and incomes from bear hunting were assessed through a questionnaire survey to hunting managers. We used a two-sex matrix model of the bear population to investigate the sustainability of current hunting levels. The model will show current population estimates for the bear population size given that the population appears to be stable with the current hunting quota. This study demonstrates that a loss of bear trophy hunting would result in a substantial loss of income to the hunting organisations, and that changes in management are required while trends in bear populations are to be robustly assessed.
5. Kinahan A, Bunnefeld N. Effectiveness and cost efficiency of monitoring mountain nyala in the Bale Mountains National Park, Ethiopia. Endangered Species Research (provisionally accepted)
6. Milner-Gulland, E.J. (2012) Interactions between human behaviour and ecological systems. Phil. Trans. Roy. Soc. B. 367: 270-278, http://rstb.royalsocietypublishing.org/content/367/1586/270.short
Research on the interactions between human behaviour and ecological systems tends to focus on the direct effects of human activities on ecosystems, such as biodiversity loss. There is also increasing research effort directed towards ecosystem services. However, interventions to control people's use of the environment alter the incentives that natural resource users face, and therefore their decisions about resource use. The indirect effects of conservation interventions on biodiversity, modulated through human decision-making, are poorly studied but are likely to be significant and potentially counterintuitive. This is particularly so where people are dependent on multiple natural resources for their livelihoods, when both poverty and biodiversity loss are acute. An inter-disciplinary approach is required to quantify these interactions, with an understanding of human decision-making at its core; otherwise, predictions about the impacts of conservation policies may be highly misleading.
7. Schlüter M, McAllister RRJ, Hölker F, Quaas M, Arlinghaus R, Bunnefeld N, Eisenack K, Milner-Gulland EJ, Müller B, Nicholson E, Stöven M (2012) New horizons for managing the environment: A review of coupled social-ecological systems modeling. Natural Resource Modelling 25: 219-272
Conventional approaches to natural resource management are increasingly challenged by environmental problems that are embedded in highly complex systems with profound uncertainties. These so-called social-ecological systems (SESs) are characterized by strong links between the social and the ecological system and multiple interactions across spatial and temporal scales. New approaches are needed to manage those tightly coupled systems; however, basic understanding of their nonlinear behavior is still missing. Modeling is a traditional tool in natural resource management to study complex, dynamic systems. There is a long tradition of SES modeling, but the approach is now being more widely recognized in other fields, such as ecological and economic modeling, where issues such as nonlinear ecological dynamics and complex human decision making are receiving more attention. SES modeling is maturing as a discipline in its own right, incorporating ideas from other interdisciplinary fields such as resilience or complex systems research. In this paper, we provide an overview of the emergence and state of the art of this cross-cutting field. Our analysis reveals the substantial potential of SES models to address issues that are of utmost importance for managing complex human-environment relationships, such as: (i) the implications of ecological and social structure for resource management, (ii) uncertainty in natural and social systems and ways to address it, (iii) the role of coevolutionary processes in the dynamics of SESs, and (iv) the implications of microscale human decision making for sustainable resource management and conservation. The complexity of SESs and the lack of a common analytical framework, however, also pose significant challenges for this emerging field. There are clear research needs with respect to: (i) approaches that go beyond rather simple specifications of human decision making, (ii) development of coping strategies to deal with (irreducible) uncertainties, (iii) more explicit modeling of feedbacks between the social and ecological systems, and (iv) a conceptual and methodological framework for analyzing and modeling SESs. We provide ideas for tackling some of these challenges and indicate potential key focal areas for SES modeling in the future.
8. Majic A, Marino A, Huber D, Bunnefeld N (2011) Dynamics of public attitudes toward bears and the role of bear hunting in Croatia. Biological Conservation 144: 3018-3027, http://www.sciencedirect.com/science/article/pii/S0006320711003508
Successful carnivore conservation depends on public attitudes and acceptance levels of carnivores, and these are likely to change as circumstances change. Attitude studies repeated in time that can demonstrate such change are rare. Our study surveyed Croatian rural inhabitants in 2002 and in 2008 and analyzed their responses to detect a change in attitudes toward brown bears (Ursus arctos) over time. Important developments occurring in Croatia at the time of our research included a more centralized and more clearly defined bear management strategy, and an increase in the bear population. We constructed models to explain respondent’s value orientations, their level of perceived threat and their acceptance capacity for bears. Findings show that while value orientations and the overall level of perceived threat did not change over time, bear acceptance capacity was reduced. This suggests that the increase in the bear population and perhaps the more centralized bear management reduced respondents’ willingness to accept a larger bear population. We conclude that continuous public involvement in bear management is essential in order to maintain a feeling of control over the bear among the local population. Furthermore we argue that hunting is an important form of public involvement in the region, serving to reinforce existence and bequest values of the bear and increase its public acceptance.
9. Bunnefeld N, Hoshino E, Milner-Gulland E.J. (2011) Management Strategy Evaluation: A powerful tool for conservation? Trends in Ecology and Evolution 26: 441-447, http://www.cell.com/trends/ecology-evolution/abstract/S0169-5347%2811%2900133-9
Game management is widely implemented in Spain, affecting more than 70 % of land cover. Management intensity may be linked to the financial aims of hunting estates, but no study of these aspects has been developed in Spain, where commercial hunting is common. Through interviews with game managers and field surveys, we quantified physical and economic traits, management techniques, and hunting methods in a sample of 59 small-game hunting estates located in south-central Spain (where red-legged partridge hunting has the highest socioeconomic importance in the country). We compared non-commercial estates (aimed for leisure, managed mainly by local hunting societies) and commercial estates (aimed at financial benefit); among the latter, we also assessed “intensive” estates (a special category of commercial estates licensed to release farm-reared partridges without temporal or numerical limits throughout the hunting season). Commercial estates had more intensive management, including more and larger partridge releases, higher density of supplementary feeders and more intensive predator control. Thus, any positive or negative effects on biodiversity of these management techniques would be higher in commercial than in noncommercial estates. Commercial estates also retained more natural vegetation, which may help to enhance the landscape and biodiversity value of farmland in central Spain. On the other hand, differences in management and hunting styles were most marked between intensive and other type of estates (both commercial and non-commercial); this indicates that intensive estates are qualitatively different from other small-game estates, both ecologically (hunting based on releases and driven shooting) and economically (higher inputs and outputs). It would be desirable to find ways to quantify the environmental or social costs and benefits of different management techniques, and integrate them in the economics of hunting estates.
10. Milner-Gulland EJ (2011) Integrating fisheries approaches and household utility models for improved resource management. PNAS 108: 1741-1746, http://www.pnas.org/content/early/2011/01/04/1010533108
Natural resource management is littered with cases of overexploitation and ineffectual management, leading to loss of both biodiversity and human welfare. Disciplinary boundaries stifle the search for solutions to these issues. Here, I combine the approach of management strategy evaluation, widely applied in fisheries, with household utility models from the conservation and development literature, to produce an integrated framework for evaluating the effectiveness of competing management strategies for harvested resources against a range of performance metrics. I demonstrate the strengths of this approach with a simple model, and use it to examine the effect of manager ignorance of household decisions on resource management effectiveness, and an allocation tradeoff between monitoring resource stocks to reduce observation uncertainty and monitoring users to improve compliance. I show that this integrated framework enables management assessments to consider household utility as a direct metric for system performance, and that although utility and resource stock conservation metrics are well aligned, harvest yield is a poor proxy for both, because it is a product of household allocation decisions between alternate livelihood options, rather than an end in itself. This approach has potential far beyond single-species harvesting in situations where managers are in full control; I show that the integrated approach enables a range of management intervention options to be evaluated within the same framework.
11. Milner-Gulland EJ, Arroyo B, Bellard C, Blanchard J, Bunnefeld N, Delibes-Mateos M, Edwards C, Nuno A, Palazy L, Reljic S, Riera P, Skrbinsek T. (2010) New directions in Management Strategy Evaluation through cross-fertilisation between fisheries science and terrestrial conservation. Biology Letters 6: 719-722
On 1 and 2 June 2010, an international meeting was held at the University of Paris Sud XI, France, organized within the framework of the EU FP7 consortium project HUNT, to bring together fisheries and conservation scientists to discuss a unified framework for the future of management strategies for harvested species.
Unpublished MSc theses available online at www.iccs.org.uk
12. Emma Knott (2011), A bioeconomic model for hunting brown bears in Croatia (with Prof D. Huber, University of Zagreb), http://www.iccs.org.uk/wp-content/thesis/consci/2011/Knott.pdf
13. Arash Ghoddousi (2010) Movement ecology of GPS-collared Brown bears in Croatia and Slovenia (with Dr K. Jerina, University of Ljubljana & Prof D. Huber, University of Zagreb), http://www.iccs.org.uk/wp-content/thesis/consci/2010/Ghoddousi.pdf
14. Agnese Marino (2010) Public attitudes toward the brown bear in Croatia: a change over time. (with A. Majic, University of Ljubljana), http://www.iccs.org.uk/wp-content/thesis/consci/2010/Marino.pdf
15. George Swan (2011), Spatial variation in Common Buzzard (Buteo buteo) abundance and diet in relation to habitat type and prey abundance (with Prof Steve Redpath, University of Aberdeen), http://www.iccs.org.uk/wp-content/thesis/consci/2011/Swan.pdf
16. Bronwen Daniel (2010) Effects of sporting estate management practices on biodiversity in Scotland (with Dr R. Bryce & Prof S. Redpath, University of Aberdeen), http://www.iccs.org.uk/wp-content/thesis/consci/2010/Bronwen.pdf
Additional papers in the pipeline
We envisage another 2-3 papers from the Tanzania case study (including an estimate of bushmeat hunting and consumption rates in the Western Serengeti; and an analysis of the effects of management interventions on population dynamics of Serengeti ungulates).
We will be working this summer on a paper on the Spanish partridge case study, with B. Arroyo and M. Delibes.
There is the potential for a lynx case study paper as well, depending on contact from the Norwegian team (E. Nilsen, J. Linnell).