742 T. S. F. Adams et al.


TABLE 1 Summary of the study fields, showing whether they were used as control or treatment, during which season they were included in the study, village location, field size, distance from a wildlife corridor, distance from another field and the type of crops grown.


Field


number 1


2 3 4 5 6 7


8 9


10 11 12 13 14 15


16 17 18


Control/ treatment1 Season2 Village


Treatment 1


Field size (ha)


Mabele 1.59


Treatment Both Mabele 0.65 Treatment Both Mabele 3.20 Treatment 1 Treatment 1 Treatment 1 Treatment 2


Kavimba 3.90 Kachikau 2.48 Kavimba 0.32 Kavimba 5.52


Treatment 2 Control 1 Control 1


Control 1 Control 2


Control/ treatment


Control/ treatment


Control/ treatment


Control/ treatment


Kavimba 1.50 Mabele 1.36 Mabele 0.80


Kavimba 5.60 Mabele 1.31


Control Both Mabele 1.30 Control 2 2


Kavimba 0.87 Muchenje 0.37


2 2 2


Mabele 3.26 Kavimba 6.13 Kavimba 3.54


Distance from corridor (m)


0 0


0 0 0


222 371


0


513 282


0 0 0 0


280 0 0 0


1Fields 15–18 started as control fields and became treatment fields within the same season. 2Season 1 = 2016/2017; season 2 = 2017/2018.


fields if the lights were successful in deterring them from a treatment field.


Solar-powered strobe light barriers


We assisted participating farmers with setting up a solar- powered strobe barrier for treatment fields. Farmers were responsible for the security of the lights, and we agreed with them that if any lights were stolen or broken then all remaining lights would be removed. A barrier consisted of 6–13 solar-powered LED strobe lights (Repro Supplies, Boksburg, South Africa) that were set up adjacent to the growing crop, 1.5–1.7 m off the ground at 10-m intervals. The lights were purchased from South Africa at a cost of ZAR 220 per unit, and with the internal solar charger sys- tem, they can run independently for up to 3 years. The lights were placed on the side of the field that the farmer indicated the elephants were most likely to pass by or enter the field from. Each light in the barrier constantly flashed a single colour (red, green, amber, white, blue or yellow) both day and night. To reduce habituation, the colour pattern of the array was rotated weekly, so that it appears differently to the elephants each time they pass by. Lights remained


in place until the farmer completed their harvest, for 1–3 months during January–June. Harvest time depended on when an individual farmer ploughed and planted their field within that season. To verify whether elephants crossed the barriers or not,


we gathered reports about elephant movements in the area, and deployed a camera trap (Bushnell Trophy Cam Brown HD, Bushnell Corporation, Overland Park, USA) perpen- dicular to the light barriers at each treatment field, at a distance of 1–10 m from the lights. We downloaded images weekly.


Assessing incursions


We recorded elephant behaviour and activity in and around the selected fields over successive years, during the 2016/ 2017 and 2017/2018 crop seasons. We based our definitions of elephant behaviour on King et al. (2011), with an incur- sion being defined as an elephant, or a group of elephants, entering a field from any direction, which included both walking through a field and feeding on the crop. If the same elephants left the field and then re-entered it in the same night, we recorded the second event as a second


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


Distance to another crop field (m)


0


50 0


1,065 1,006 323 0


0


123 0


0 0 0


135 0


0 0 0


Crops grown


Sorghum, maize, sweet reed


Sorghum, maize, beans Sorghum, maize Sorghum, maize Maize, sweet reed Sorghum, maize


Sorghum, maize, watermelon


Maize, cabbage, tomatoes, pumpkin


Sorghum, maize, sweet reed


Sorghum, maize Maize, beans Sorghum


Sorghum, maize Sorghum, maize Sorghum, maize


Sorghum, maize Maize


Sorghum, maize


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