INVESTIGATING THE COVARIANCE BETWEEN RAINFALL AND MALE ELEPHANT MOVEMENT - To Reduce Human-Elephant Conflict

Abstract: Human-wildlife conflict threatens the survival of a range of species, including the savannah elephant (Loxodonta africana). Villages bordering the Makgadikgadi Pans National Park in Botswana are among the most affected by human-elephant conflict, and it is crucial to identify contributing factors to develop mitigation strategies. Researchers in the area have suspected a potential covariance between rainfall and elephant movement. However, it is difficult to separate patterns that are directly related to rainfall from those that are primarily governed by circannual cycles related to elephant life history, because rainfall is highly seasonal in this region. This study investigated the relative effect of rainfall versus time of year on movement patterns, specifically among males in musth (a condition of heightened testosterone recognized by secretion from temporal glands) and older males, since these are the most prone to aggression and crop raiding, respectively. Data on rainfall and elephant sighting collected between 2012 and 2022 were analyzed using generalized additive models (GAMs), controlling for day of year and moving averages of rainfall. Results showed that all response variables were mainly associated with day of year rather than rainfall. Although rain was slightly associated with the probability of a sighting including an older male, this partial covariation was minimal compared to that of day of year. The probability of a sighting including a musth male showed no association with rain. When modelling partial effect of day of year, the probability of a sighting including a musth male was highest in March/April (corresponding to the middle of the farming season) and lowest in September (end of the dry season). The probability of a sighting containing an older male showed the opposite pattern to that of musth males, which is surprising considering older males are the main crop raiders. It is possible, however, that this pattern does not reflect the experience of locals since the research area is slightly removed from the farms. Further studies are required to investigate reasons for the different movement patterns shown by older males and males in musth, as well as the overall probability of encountering an older male when total number of sightings is taken into account.