740 T. S. F. Adams et al.
techniques that farmers can and want to implement (Davies et al., 2011; Gunaryadi et al., 2017). The systematic study of negative human–elephant inter-
actions and possible interventions began in the mid 1990s and a wide range of mitigation methods have since been developed and tested in areas with high levels of such inter- actions in both Africa and Asia (Hoare, 2015; Shaffer et al., 2019). Many methods focus on exclusion, aiming to prevent negative interactions by separating elephants and people (Shaffer et al., 2019). These methods include fencing, olfac- tory and auditory deterrents, explosive devices, beehives, ecological wildlife corridors and zonation (Osborn & Rasmussen, 1995;O’Connell-Rodwell et al., 2000; Sitati et al., 2003; Parker & Osborn, 2006; Sitati & Walpole, 2006; Graham & Ochieng, 2008; King et al., 2009, 2011; Davies et al., 2011; Hoare, 2015; Adams et al., 2017a). Electric fences in particular have been used extensively in southern Africa (O’Connell-Rodwell et al., 2000; Hoare, 2003; Parker et al., 2007; Davies et al., 2011) and although they are often effective in separating elephants and areas used by people, their dependence on electricity makes them costly to install and maintain (Hoare, 2003, 2015). The same applies to Geo-fencing, an alert system working with GPS collars, which is effective when known so-called problemelephants can be monitored and deterred from en- tering a particular area (Hoare, 2015).However, Geo-fencing is time- and cost-intensive, and not effective in areas that are heavily frequented by elephants. As a result lower-cost solu- tions have also been developed. For example, the burning of chili seeds is an effective elephant deterrent for protecting small crop fields or nurseries, although the success of this intervention depends on the method of application (Osborn & Rasmussen, 1995; Parker & Osborn, 2006;Sitati&Walpole, 2006). Beehive fences have also been successfully installed to reduce negative interactions between elephants and people, primarily in East Africa (King et al., 2009, 2011, 2017); they are relatively low-cost and can provide additional economic and nutritional returns to farmers (King et al., 2017). Even when effective in certain situations, no single solu-
tion can be expected to be successful in all circumstances. For example, the demand for chilli peppers in the quantities needed to be effective can surpass the supply in some re- gions (Parker & Osborn, 2006; Hoare, 2015). Beehive fences may not be effective in areas with a low bee population, where elephants do not display strong avoidance behaviours (Adams, 2016b). There remains a need for research and development of additional mitigation tools and strategies, especially given that elephants are intelligent (Mumby & Plotnik, 2018) and can become habituated by repeated use of existing tools (O’Connell-Rodwell et al., 2000). Botswana is home to the largest elephant population in
Africa (c. 125,000; Chase et al., 2019). The Chobe District has an estimated population of 32,712 elephants in the dry season (Chase et al., 2019), which live alongside a human
population of 23,347 (Census Office, 2015). As a result, this district is a hotspot for human–elephant interactions in Botswana (Gupta, 2013; Adams et al., 2017a), and elephants cause the greatest proportion (48%) of problem animal control reports in the area (DWNP, 2018). Incidences of elephants feeding in crop fields and gardens, and causing other property damage, are the most common reports received by the problem animal control officers in the Department of Wildlife and National Parks. Given the size of the elephant population in Botswana and the high rates of problem animal control reports, developing successful miti- gation solutions is of high priority to stakeholders in the country (Adams et al., 2017b). We tested a novel method for reducing human–
elephant interactions in the Chobe District of Botswana. Our objective was to investigate whether night-time incur- sions into fields previously damaged by elephants could be reduced by installing solar-powered strobe light barriers. Although similar techniques have been tested to deter pre- dators and birds from livestock, gardens and properties (Lesilau et al., 2018;Foxlights, 2019;NiteGuard, 2019;Ohrens et al., 2019; Predator Guard, 2019) to our knowledge this is the first trial testing whether solar-powered strobe light barriers can deter elephants from entering fields. Based on results from other species (e.g. lions; Lesilau et al., 2018; Ohrens et al., 2019) and observations of elephants retreat- ing from single torches (Davies et al., 2011) and vehicle lights (Adams, 2016a) we predicted that solar-powered strobe light fences would reduce the frequency of field incursions by elephants.
Study area
We conducted the study near the villages of Muchenje,Mabele, Kavimba and Kachikau (combined human population 4,034; Census Office, 2015)inthe ChobeEnclave,inthe 22,560 km2 semi-arid Chobe District of northern Botswana (Fig. 1). The area is surrounded by unfenced protected wildlife
areas, the 10,740 km2 Chobe National Park and the 1,545 km2 Chobe Forest Reserve on the eastern and southern bound- aries of the Chobe Enclave and the Namibian border and the Kwando-Linyanti-Chobe river system on the northern and western boundaries (Fig. 1). A large proportion of the Chobe Enclave is a seasonal floodplain that is reliant on rainfall in the mountains of Angola. The soil in Chobe District is predominately Kalahari sand, but is nutrient-rich in the floodplain, characterized by alluvial and lacustrine deposits. The district contains the only forest in Botswana with a relatively closed canopy (Lepetu, 2007). The vegeta- tion is dominated by Baikeaea plurijuga and Acacia erioloba and is consistent with the Zambezian biogeographical region (Lepetu, 2007). North Botswana has four seasons, including a hot dry (August–October), wet (November–March), post-
Oryx, 2021, 55(5), 739–746 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319001182
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