Temporal Partitioning and Overlapping Use of a Shared Natural Resource by People and Elephants

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

Chilli-briquettes modify the temporal behaviour of elephants, but not their numbers

Crop loss to foraging elephants is one of the most significant causes of conflict between people and elephants in areas where wild elephants share resources with people. Effective solutions to reduce the effects of human–elephant conflict on local livelihoods are thus essential to foster coexistence between elephants and people. We assessed the effectiveness of chilli-briquettes (bricks made of dry chilli, elephant dung and water) in altering elephants use of space in the eastern Okavango Panhandle, Botswana. We burned > 600 briquettes during the night over a 2-month period to test five treatments: frequent burning of (1) chilli and (2) chilli-free briquettes, occasional burning of (3) chilli and (4) chilli-free briquettes, and (5) a control treatment. Using camera traps and footprint surveys we assessed the number of elephants that used experimental sites, and the times at which they did so. We found elephants changed their movement behaviour from predominantly nocturnal to diurnal in areas where chilli-briquettes were burned throughout the night; however, there was no difference in the mean numbers of individuals between treatments with and without chillies. In other words, chilli-briquettes had a repellent but not a deterrent effect on elephants, keeping them away only at times when chilli-briquettes were smouldering. Based on these findings we recommend the use of chilli-briquettes as a method to deter elephants in the short term. In the long term, chilli-briquettes should be applied in combination with other larger-scale mitigation approaches, such as land management and cooperative community-based tools

Elephant space-use is not a good predictor of crop-damage

Elephant crop-damage is a consequence of interactions between people and elephants that impact people's livelihoods and biodiversity conservation efforts. Conflicts between people and elephants usually occur when there is overlap in elephant and human space-use leading to competition for resources. Therefore, understanding space-use patterns by elephants is key to alleviating negative human-elephant interactions. In the eastern Okavango Panhandle (Botswana), >16,000 people share resources with 18,000 elephants. Using data from 20 GPS-collared elephants, we investigated elephant space-use in relation to landscape variables during the day and night throughout the year and during the dry, wet and crop-damage seasons. We compared elephant space-use and crop-damage occurrence during the crop-damage seasons of 2014–2016. We found that elephant space-use was determined primarily by distance to waterholes and areas away from agricultural fields. However, predicting elephant space-use at the large scale was challenging. In particular, during the crop-damage season when the relationship between crop-damage events and elephant distribution was found to be non-linear. This revealed that areas that elephants frequently use might not be good indicators of the likelihood of crop-damage. Based on our findings, we suggest deterring elephants from peoples' crops at the local scale is the most appropriate strategy for reducing elephant impacts on crops, alongside landscape scale interventions. We encourage future studies to use combinations of spatiotemporal methods, as well as practitioners to focus their efforts at the local scale, protecting elephant corridors, and supporting farmers to collaboratively work to decrease elephant crop-loss

Elephant space-use is not a good predictor of crop-damage

Elephant crop-damage is a consequence of interactions between people and elephants that impact people's livelihoods and biodiversity conservation efforts. Conflicts between people and elephants usually occur when there is overlap in elephant and human space-use leading to competition for resources. Therefore, understanding space-use patterns by elephants is key to alleviating negative human-elephant interactions. In the eastern Okavango Panhandle (Botswana), >16,000 people share resources with 18,000 elephants. Using data from 20 GPS-collared elephants, we investigated elephant space-use in relation to landscape variables during the day and night throughout the year and during the dry, wet and crop-damage seasons. We compared elephant space-use and crop-damage occurrence during the crop-damage seasons of 2014–2016. We found that elephant space-use was determined primarily by distance to waterholes and areas away from agricultural fields. However, predicting elephant space-use at the large scale was challenging. In particular, during the crop-damage season when the relationship between crop-damage events and elephant distribution was found to be non-linear. This revealed that areas that elephants frequently use might not be good indicators of the likelihood of crop-damage. Based on our findings, we suggest deterring elephants from peoples' crops at the local scale is the most appropriate strategy for reducing elephant impacts on crops, alongside landscape scale interventions. We encourage future studies to use combinations of spatiotemporal methods, as well as practitioners to focus their efforts at the local scale, protecting elephant corridors, and supporting farmers to collaboratively work to decrease elephant crop-loss

Summary of best historical and contemporary models.

<p>Summary of best historical and contemporary models.</p

Summary of model selection with corrected Akaike’s Information Criterion (AICc).

<p>Summary of model selection with corrected Akaike’s Information Criterion (AICc).</p

Temporal interaction between reported raid incidents and HEC drivers.

<p>(A) corresponds to the predicted number of reported raids incidents (RRI) per person (back) and per elephant (grey), (B) agricultural land allocated (ALA) per person (back) and elephant (grey); and (C) estimated raiding incidents per ha of agricultural land allocated (ALA). Dashed lines correspond to predictions from the historical model (1970s - 2015) and continuous lines to predictions from the contemporary model (2008–2015).</p

Location of villages in the eastern Okavango Delta Panhandle (Botswana).

<p>Circles represent the thirteen villages (i.e. Mohembo East, Kauxwi, Tobera, Xakao, Sekondomboro, Ngarange, Mogotho, Mokgacha, Seronga, Gunotsoga, Eretsha, Beetsha and Gudigwa) along the Okavango River. The small southern Africa inset map shows the location of the study area in northern Botswana in white. This image is not identical to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0178840#pone.0178840.g002" target="_blank">Fig 2</a> in Songhurst and Coulson (2014), and therefore it is for illustrative purposes only.</p