Panic at the disco: solar-powered strobe light barriers reduce field incursion by African elephants Loxodonta africana in Chobe District, Botswana

Animal migration in the Anthropocene: threats and mitigation options

Animal migration has fascinated scientists and the public alike for centuries, yet migratory animals are facing diverse threats that could lead to their demise. The Anthropocene is characterised by the reality that humans are the dominant force on Earth, having manifold negative effects on biodiversity and ecosystem function. Considerable research focus has been given to assessing anthropogenic impacts on the numerical abundance of species/populations, whereas relatively less attention has been devoted to animal migration. However, there are clear linkages, for example, where human-driven impacts on migration behaviour can lead to population/species declines or even extinction. Here, we explore anthropogenic threats to migratory animals (in all domains - aquatic, terrestrial, and aerial) using International Union for the Conservation of Nature (IUCN) Threat Taxonomy classifications. We reveal the diverse threats (e.g. human development, disease, invasive species, climate change, exploitation, pollution) that impact migratory wildlife in varied ways spanning taxa, life stages and type of impact (e.g. from direct mortality to changes in behaviour, health, and physiology). Notably, these threats often interact in complex and unpredictable ways to the detriment of wildlife, further complicating management. Fortunately, we are beginning to identify strategies for conserving and managing migratory animals in the Anthropocene. We provide a set of strategies that, if embraced, have the potential to ensure that migratory animals, and the important ecological functions sustained by migration, persist.

Testing the Effectiveness of the "Smelly" Elephant Repellent in Controlled Experiments in Semi-Captive Asian and African Savanna Elephants

Crop-raiding by elephants is one of the most prevalent forms of human-elephant conflict and is increasing with the spread of agriculture into wildlife range areas. As the magnitude of conflicts between people and elephants increases across Africa and Asia, mitigating and reducing the impacts of elephant crop-raiding has become a major focus of conservation intervention. In this study, we tested the responses of semi-captive elephants to the "smelly" elephant repellent, a novel olfactory crop-raiding mitigation method. At two trial sites, in Zambia and Thailand, African elephants (Loxodonta africana) and Asian elephants (Elephas maximus) were exposed to the repellent, in order to test whether or not they entered an area protected by the repellent and whether they ate the food provided. The repellent elicited clear reactions from both study groups of elephants compared to control conditions. Generalised linear models revealed that the elephants were more alert, sniffed more, and vocalised more when they encountered the repellent. Although the repellent triggered a response, it did not prevent elephants from entering plots protected by the repellent or from eating crops, unlike in trials conducted with wild elephants. Personality played a role in responses towards the repellent, as the elephants that entered the experimental plots were bolder and more curious individuals. We conclude that, although captive environments provide controlled settings for experimental testing, the ecological validity of testing human-elephant conflict mitigation methods with captive wildlife should be strongly considered. This study also shows that understanding animal behaviour is essential for improving human-elephant coexistence and for designing deterrence mechanisms. Appreciating personality traits in elephants, especially amongst "problem" elephants who have a greater propensity to crop raid, could lead to the design of new mitigation methods designed to target these individuals.

A synthesis of human conflict with an African megaherbivore; the common hippopotamus

The common hippopotamus is an extant African megaherbivore that is relatively understudied by scientists and underfunded by conservation organisations. Conflict with people, however, is a major concern given the danger that hippos pose to human life. Moreover, very little is known about human–hippo conflict (HHC), and experimental fieldwork on mitigation methods has hardly been conducted. Here we conduct an exhaustive review of the primary and grey literature outlining how the conflict between people and hippos arises, the impacts of conflict on both human communities and hippo populations, and all known intervention measures. Our review highlights the effectiveness of barriers around crops, riparian buffer zones (that exclude cattle and crop planting), and payments for environmental services as tools to mitigate HHC. This study also highlights the knowledge gaps in HHC research, particularly the spatial scale of HHC, the lack of field experimental research on deterrents, and a paucity of knowledge on outcomes of projected climate change and HHC.

The Virtual Fence Dynamic: a Breakthrough for Low-Cost and Sustainable Mitigation of Human-Elephant Conflict in Subsistence Agriculture?

Attempts to deter elephants from entering crop fields and human settlements in Africa have used various barriers (e.g. electric fences, chilli fences, beehive fences or plant barriers), situated on or very near the boundaries of fields or villages, with rather variable success. We explored a very simple new barrier concept based upon re-arranging the layout of foreign stimuli already known to arouse suspicion and fear among elephants. Deterrence involved deploying unnaturally scented objects on and across their pathways of habitual movement leading to crop field clusters. Elephants are suspicious of unpleasant olfactory stimuli, like string or cloth saturated with pungent-smelling chilli oil, old engine oil, or creosote and dislike ‘chilli smoke’. Foreign visual items like plastic bottles, reflective metal strips and cow bells possibly reinforced suspicion of these unpleasant scents and influenced the deterrent effect. These flimsy items deployed over very short distances merely acted as a bluff to ‘problem elephants’ that people were actively trying to impede their progress, and the vast majority chose to turn back or deviate substantially. Thus we coined the term a ‘soft virtual boundary’. We demonstrate that placing virtual boundaries away from village and agricultural lands, forces elephants to encounter them upon leaving their daytime refuges, while still in natural habitat. The suspicion and fear generated here considerably reduces elephants’ determination to proceed onwards to risk crop raiding. When multiple, small virtual boundaries are strategically moved around at intervals, a ‘virtual fence dynamic’ delivers an enduring deterrent effect. In ten study areas in two countries over seven years this technique led to considerable and consistent reductions in crop damage levels of up to 95% in places. Because these methods (i) completely rely on local knowledge, (ii) were exceptionally low cost and (iii) demonstrated rapid results, the ‘buy-in’ from affected communities of small-scale subsistence farmers was immediate and very enthusiastic. So this strategy has the potential to remove the most intractable stumbling block to the sustainability of human-elephant conflict mitigation efforts in smallholder agriculture – reliance upon conservation donor funding for very costly and problematic mitigation measures like fencing, compensation schemes and elephant translocations.

Acknowledging the Relevance of Elephant Sensory Perception to Human–Elephant Conflict Mitigation

Simple Summary

Elephants have a unique sensory perspective of the world, using their complex olfactory and auditory systems to make foraging and social decisions. All three species of elephants are endangered and inhabit environments, which are being affected rapidly by human development. Anthropogenic disturbances can have significant effects on elephants’ abilities to perceive sensory information and communicate with one another, potentially further endangering their survival. Conflicts over high-quality resources also arise from the overlapping habitation of humans and elephants. While many different methods have been employed to reduce this conflict, we propose that elephants’ unique olfactory and acoustic sensory strengths be considered in future mitigation strategies to achieve coexistence.

Abstract

Elephants are well known for their socio-cognitive abilities and capacity for multi-modal sensory perception and communication. Their highly developed olfactory and acoustic senses provide them with a unique non-visual perspective of their physical and social worlds. The use of these complex sensory signals is important not only for communication between conspecifics, but also for decisions about foraging and navigation. These decisions have grown increasingly risky given the exponential increase in unpredictable anthropogenic change in elephants’ natural habitats. Risk taking often develops from the overlap of human and elephant habitat in Asian and African range countries, where elephants forage for food in human habitat and crop fields, leading to conflict over high-quality resources. To mitigate this conflict, a better understanding of the elephants’ sensory world and its impact on their decision-making process should be considered seriously in the development of long-term strategies for promoting coexistence between humans and elephants. In this review, we explore the elephants’ sensory systems for audition and olfaction, their multi-modal capacities for communication, and the anthropogenic changes that are affecting their behavior, as well as the need for greater consideration of elephant behavior in elephant conservation efforts.