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He, H., Buchholtz, E., Chen, F., Vogel, S. and Yu, C.A.A., 2022. An agent-based model of elephant crop consumption walks using combinatorial optimization. Ecological Modelling, 464, p.109852. doi.org/10.1016/j.ecolmodel.2021.109852
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Abstract
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Publisher Website
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February 2022
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<b>Conceptual context: </b>Wildlife crop consumption is a worldwide problem. This paper builds on the theoretical framework of profit and utility maximization from economics as established in the theory of optimal foraging, bringing this perspective to the issue of wildlife crop consumption by testing whether elephants forage for crops in an optimal way.<br><br><b>Methodological approach: </b>Using combinatorial optimization in an agent-based model, in which elephants’ objective is to find a valid walk that maximizes their energy balance. We used empirical data from GPS collars on African savanna elephants to train and test the model.<br><br><b>Main results and conclusions: </b>When we focused solely on which terrain blocks the elephants of GNP visit and spend time in, our ABM got 56 percent of these blocks correct. Our ABM performed roughly 25 percent better than two alternative models, including the random walk model. In both subsamples of data that we looked at, the ABM performed better in terms of fitting the data on real walks than the alternative models. The ABM's performance improved, and the alternative models’ performance worsened, when we only looked at data on real walks that involve crop consumption. This suggests that there is more randomness involved when elephants are engaged in foraging activity that do not include crop consumption. At the same time, elephant walks involving crop consumption seem to more closely follow optimizing principles.<br><br>Findings from this ABM approach support ecological understanding of elephant crop foraging, highlighting the optimal movements involved in crop foraging events as well as the importance of trespassing costs and landscape configuration. It may give conservationists and policy-makers a starting point to use in formulating policies to minimize the harms and costs that result from elephant crop consumption.
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Buchholtz, E.K., Stronza, A., Songhurst, A., McCulloch, G. and Fitzgerald, L.A., 2020. Using landscape connectivity to predict human-wildlife conflict. Biological Conservation, 248, p.108677. doi.org/10.1016/j.biocon.2020.108677
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Abstract
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August 2020
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Human-wildlife conflict has serious conservation consequences, both for populations of wildlife and for the people who live alongside them. Connectivity analyses can incorporate species-specific landscape resistance, and therefore have the potential to be used to understand where wildlife moves and causes conflict with people. We used circuit theory to develop connectivity models for the African savanna elephant in northwestern Botswana based on step-selection functions of movement data for 15 elephants and tested whether areas of high connectivity were correlated with occurrences of crop raiding. We used government records and field assessments of crop-raiding incidents between 2010 and 2016 to quantify conflict, which we predicted would correlate with landscape connectivity. The step-selection model revealed that linear boundaries such as rivers, fences, and dune crests were barriers to movement that impacted connectivity, while high vegetation index values and distance from villages were strong positive predictors of movement. Connectivity values were positively and significantly correlated with frequency of conflict incidents (<i>p</i> < 1.5e−06) over a six-year time span. However, connectivity had no predictive value for whether fields were raided (<i>p</i> < .54) or how frequently a field was raided (<i>p</i> < .77) during a single growing season. This study shows that connectivity may be a useful metric for predicting patterns of conflict occurrence over broad temporal scales, but may have limited predictive power at shorter time scales. It is crucial that conservation and conflict mitigation efforts recognize that methods may be appropriate for different purposes at different scales.
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Buchholtz, E.K., Spragg, S., Songhurst, A., Stronza, A., McCulloch, G. and Fitzgerald, L.A., 2021. Anthropogenic impact on wildlife resource use: Spatial and temporal shifts in elephants’ access to water. African Journal of Ecology, 59(3), pp.614-623. https://doi.org/10.1111/aje.12860
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Abstract
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Publisher Website
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March 2021
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Expansion of human settlements and development have undeniable impacts on wildlife and habitats. Yet wildlife continues to persist in human-modified environments. While shifting patterns of wildlife landscape use in response to development is well established, less is known about how risk avoidance by animals impacts their resource access. Our research addresses this question by assessing spatial and temporal patterns in access to water resources for savannah elephants (<i>Loxodonta africana</i>) relative to anthropogenic features in the Okavango Panhandle of Botswana. We combined GPS collar data from 39 elephants (2014–2018) with spatial data on permanent water sources and human development to quantify patterns of water access. We modelled a multi-scale resource selection function that showed elephants selected water access points in areas with less human development (<i>p</i> < 0.0151). Elephants visited water more evenly across day and night in areas with no buildings nearby, but shifted to a significantly more nocturnal pattern in areas of higher building density (ANOVA, <i>p</i> < 0.001). Analysing spatial and temporal patterns of elephant resource access in the context of anthropogenic features provides compelling insight into the potential consequences of human-modified landscapes on the behaviour, fitness, and persistence of threatened species and our coexistence with them.
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Buchholtz, E.K., Redmore, L., Fitzgerald, L.A., Stronza, A., Songhurst, A. and McCulloch, G., 2019. Temporal partitioning and overlapping use of a shared natural resource by people and elephants. Frontiers in Ecology and Evolution, 7, p.117. doi.org/10.3389/fevo.2019.00117
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Abstract
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April 2019
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In social-ecological systems around the world, human-wildlife interactions are on the rise, often with negative consequences. This problem is particularly salient in areas where populations of humans and wildlife are increasing and share limited space and resources. However, few studies look at how both people and wildlife navigate shared spaces. To better examine people and wildlife within the same environment, we used methods from social science and spatial ecology to investigate how humans and elephants in Botswana utilize trees, a shared natural resource. Trees provide an opportunity to study shared resource use because they are important for people as firewood and for elephants as food and habitat. We compared tree species gathered on 49 firewood collections with the species damaged by elephants in 83 vegetation plots. We found that many tree species were damaged by elephants in ways that would generate firewood. There was also a strong overlap in the tree species that people collected and the species that elephants browsed and/or damaged. We compared spatially-explicit firewood collection locations and movement data from elephant GPS collars to model resource selection by people and elephants. Proximity to settlements was a strong driving factor for people in firewood collection, while various factors including vegetation characteristics played a role in predicting elephant movement. We found that areas where people collect firewood were negatively correlated with daytime elephant movement and positively correlated with nighttime elephant movement. We further compared the times that people collected firewood with the times when elephants were near the villages and found that people collected firewood during daylight hours when elephants were not nearby, providing further evidence of temporal partitioning. People and elephants utilized the same species of trees, and also had correlated spatial patterns of resource selection. Therefore, elephant foraging of trees provides a previously unrecognized utility to people in the form of firewood creation, and temporal partitioning allows this to occur without direct human-elephant interaction.
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Buchholtz, E.K., M. McDaniels, G. McCulloch, A. Songhurst, and A. Stronza (2023). A mixed-methods assessment of human-elephant conflict in the Western Okavango Panhandle, Botswana. People and Nature. https://doi.org/10.1002/pan3.10443
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Abstract
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February 2023
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Human-wildlife conflict, where interactions have negative impacts on both people and animals, is complex with underlying drivers and broad ecological and social impacts. From individual incidents and perceptions, to contemporary patterns and long-term trends, a range of information about human-wildlife conflict can help understand and manage challenges. However, many studies focus on a single data type or spatiotemporal scale. In the Western Okavango Panhandle in Botswana, people in rural farming communities share and compete for resources with a growing African savanna elephant population. Few previous studies have focused on human-wildlife interactions in this region. We assessed spatiotemporal trends in human-elephant conflict using reported conflict incidents (2008–2016), surveys of individual perceptions of conflict encompassing the late 1990s–2016, and detailed field raid assessments from 2016. We found complementary patterns among the data types at different geographic and spatial scales. We found that the number of annual HEC incidents have increased over time, although not evenly across space, with increases primarily in the northern region of the Panhandle. Crop raiding presents both chronic and acute challenges for farmers, with the amount of damage incurred per incident largely dependent on the size of elephant group involved rather than factors within the farmers' control such as guarding or types of crops grown. Our results provide a characterization of contemporary conflict incidents and long-term trends, despite scarce historical data. Combining the reporting and assessment data with surveyed local ecological knowledge offered a multidimensional understanding of human-wildlife conflict for a region where this information was lacking. It is an important precursor to effective and collaborative conflict management and mitigation. When possible, this mixed-methods approach may facilitate understanding for complex human-wildlife interactions and support the diverse communities and stakeholders involved with conflict-related challenges.
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Buchholtz, E., Fitzgerald, L., Songhurst, A., McCulloch, G. and Stronza, A., 2020. Experts and elephants: local ecological knowledge predicts landscape use for a species involved in human-wildlife conflict. Ecology and Society, 25(4). doi.org/10.5751/ES-11979-250426
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Abstract
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Publisher Website
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December 2020
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Local ecological knowledge (LEK) has been increasingly invoked in biodiversity monitoring and conservation efforts. Although methods involving LEK have become more widespread in ecology, it remains an undervalued source of information in understanding the ecology of wildlife in the context of human-wildlife conflict. People who regularly interact with wildlife, and often with notable consequences, as is the case with human-wildlife conflict, will likely build up ecological knowledge of that species. We gathered LEK on the landscape use of the African elephant (<i>Loxodonta Africana</i>) in a region where its range overlaps with human land use and results in conflict, the western Okavango Panhandle of Botswana. We interviewed community-defined local experts and used participatory ranking activities to gather information on landscape use of elephants. The scores from the rankings were then incorporated with environmental data following resource selection function methods common in ecology. The resulting LEK-based model had high predictive ability for elephant locations when modeled at a local scale (25 km, Spearman's rho = 0.98, <i>P</i> < 0.0001). We also calculated resource selection models using elephant telemetry data combined with the same environmental data as the LEK models. These models showed a complementary pattern, with better predictive ability at the regional scale (Spearman's rho = 0.98, <i>P</i> < 0.0001) than at the local scale (rho = 0.92, <i>P</i> < 0.0031). In addition to being used for the resource selection functions, each method provided different kinds of information on elephant landscape use. Our results support the use of LEK as a tool for understanding local patterns of wildlife landscape use in the context of human-wildlife conflict, where the knowledge can be used to complement other data across scales and the use of which can itself contribute to better conservation outcomes.
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Buchholtz, E., Fitzgerald, L., Songhurst, A., McCulloch, G. and Stronza, A., 2019. Overlapping landscape utilization by elephants and people in the Western Okavango Panhandle: implications for conflict and conservation. Landscape Ecology, 34(6), pp.1411-1423. doi.org/10.1007/s10980-019-00856-1
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Abstract
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June 2019
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Context: Many wildlife populations exist outside of protected areas, and it is necessary to understand how these animals use a landscape mosaic that includes humans. Patterns of landscape use in space and time can help inform strategies to mitigate negative interactions between people and wildlife.<br><br>Objectives: We aimed to estimate the landscape utilization of elephants where they ranged through a mosaic of human-modified land-use and undisturbed habitat to better understand spatial implications for human-wildlife interactions.<br><br>Methods: We studied locations and utilization distributions of ten bull elephants in the Western Okavango Panhandle region of Botswana. We calculated utilization distributions, patterns of landscape use, and daily movement relative to permanent water and human land-use.<br><br>Results: The annual distributions of the monitored elephants ranged from 1220 to 3446 km<sup>2</sup> and showed seasonal variation, with wet season distributions being significantly larger than dry season distributions. On average 49.4% of elephants’ core distributions in the dry season and 12.3% in the wet season fell within 5 km of human land-use. Elephants ranged increasingly farther from permanent water sources as the wet season progressed, while in the same time frame elephants moved closer on average to human land-use. Elephants were more likely to be near human land-use during the night than they were during the day. Diel patterns of elephant proximity to human land-use did not match patterns of proximity to water.<br><br>Conclusions: Conservation and management efforts must consider the diel and seasonal patterns of elephant movement in order to fully address the issue of human-elephant interactions.
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Buchholtz E. People in a biodiverse region experienced varying types and timing of conflict with multiple wildlife species. Tropical Conservation Science. 2024;17. doi:10.1177/19400829241233479
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April 2024
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