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

Simple Summary: Mitigating and reducing the impacts of elephant crop-raiding has become a major focus of conservation intervention. By observing the behaviour amongst two groups of semi-captive African and Asian elephants in Zambia and Thailand, we found that a novel olfactory crop-raiding mitigation method called the “smelly elephant repellent” elicited clear reactions from the elephants. However, unlike trials with wild elephants, the repellent did not prevent the elephants from entering areas or eating food protected by the solution. We found that elephant personality played a role in responses towards the repellent, as the individuals that entered the experimental plots were bolder and more curious individuals. 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. Understanding animal behaviour is essential for improving human–elephant coexistence and for designing deterrence mechanisms, and the smelly elephant repellent may be a useful mitigation method when used in combination with other methods. Abstract: 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

Changing seasonal, temporal and spatial crop-raiding trends over 15 years in a human-elephant conflict hotspot

Human-wildlife conflict is increasing due to rapid natural vegetation loss and fragmentation. We investigated seasonal, temporal and spatial trends of elephant crop-raiding in the Trans Mara, Kenya during 2014–2015 and compared our results with a previous study from 1999 to 2000. Our results show extensive changes in crop-raiding patterns. There was a 49% increase in incidents between 1999 -2000 and 2014–2015 but an 83% decline in the amount of damage per farm. Crop-raiding went from highly seasonal during 1999–2000 to year-round during 2014–2015, with crops being damaged at all growth stages. Additionally, we identified a new elephant group type involved in crop-raiding, comprising of mixed groups. Spatial patterns of crop-raiding also changed, with more incidents during 2014–2015 neighbouring the protected area, especially by bull groups. Crop-raiding intensity during 2014–15 increased with farmland area until a threshold of 0.4 km2 within a 1 km2 grid square, and farms within 1 km from the forest boundary, 2 km from village centres were most at risk of crop-raiding. In the last 20 years the Mara Ecosystem has been impacted by climate change, agricultural expansion and increased cattle grazing within protected areas. Elephants seem to have responded by crop-raiding closer to refuges, more frequently and throughout the year but cause less damage overall. While this means the direct economic impact has dropped, more farmers must spend more time protecting their fields, further reducing support for conservation in communities who currently receive few benefits from living with wildlife

Elephants have a nose for quantity.

Animals often face situations that require making decisions based on quantity. Many species, including humans, rely on an ability to differentiate between more and less to make judgments about social relationships, territories, and food. Habitat-related choices require animals to decide between areas with greater and lesser quantities of food while also weighing relative risk of danger based on group size and predation risk. Such decisions can have a significant impact on survival for an animal and its social group. Many species have demonstrated a capacity for differentiating between two quantities of food and choosing the greater of the two, but they have done so based on information provided primarily in the visual domain. Using an object-choice task, we demonstrate that elephants are able to discriminate between two distinct quantities using their olfactory sense alone. We presented the elephants with choices between two containers of sunflower seeds. The relationship between the amount of seeds within the two containers was represented by 11 different ratios. Overall, the elephants chose the larger quantity of food by smelling for it. The elephants' performance was better when the relative difference between the quantities increased and worse when the ratio between the quantities of food increased, but was not affected by the overall quantity of food presented. These results are consistent with the performance of animals tested in the visual domain. This work has implications for the design of future, cross-phylogenetic cognitive comparisons that ought to account for differences in how animals sense their world