People–Elephant Conflict: Monitoring how Elephants Use Agricultural Crops in Sri Lanka
Human populations are increasing rapidly throughout the Asian elephant's range. In some parts of Asia, many people are poor and landless, so they clear natural forest for agricultural use. In other parts, quickly expanding farms of such agricultural crops as sugar cane, rubber, and palm oil have replaced most of the forests that once supported wild elephant populations. These land uses increasingly displace wild elephants from their habitats and home ranges, which they travel through in search of food. Frequently, these elephants turn to farmer's crops to supplement their diets.
Many attempts have been made to prevent elephants from gaining access to crops, such as firing gunshots into the air, burning chili peppers, digging large trenches, and erecting electric fences. However, elephants often find a way around these obstacles (pushing dirt into the trenches to fill them in or breaking the fences) and the crop-raiding begins anew. In desperation, farmers may resort to injuring or even killing the elephants to protect their livelihoods. Approximately 150 elephants and 50 to 100 people are killed each year in Sri Lanka as a result of human-elephant conflicts.
Shifting Agriculture and Resource Sharing
Located on the southeastern coast of Sri Lanka, Yala National Park provides refuge for around 200 individual elephants. Covering an area of approximately the 920 square kilometers, the park still contains large areas of intact forest. Along its terrestrial borders, however, it is surrounded by extensive human settlement and agriculture.
Sri Lanka's Centre for Conservation Research (CCR), led by Dr. Prithiviraj Fernando, initiated a new project along the boundary of the southeastern section of the park to develop new strategies for mitigating people-elephant conflict. Agricultural practices in this area consist primarily of shifting agriculture, by which farmers grow crops only in the rainy season, leaving them fallow during the drier months. Between the growing seasons, grasses and small shrubs return to the fields, which local researchers have found provide important dry-season forage for the elephants. An electric fence currently separates the park from this agricultural â€œbuffer zone.â€�
CCR is working in collaboration with the Department of Wildlife Conservation to assess the feasibility of allowing elephants to forage inside the buffer zone during the dry months. By opening sections of the electric fence, elephants could go out of the park after the crops are harvested. The fence would then be closed again at the beginning of the wet season and any remaining elephants would be driven back within the park boundary. The National Zoo is supporting these efforts through the provision of satellite collars and GIS training.
As a result of this collaboration, in late 2004 three elephants were fitted with satellite collars. One of these elephants, Kandula, is a lone adult male who occupies an isolated patch of forest outside the park boundary.
Mapping Kandula's Movements
One year of data is now available from Kandula's collar since he was collared in May 2005. By analyzing this data, researchers have been able to discover some interesting trends in Kandula's movements.
Initially, the entire year of data was plotted onto one map (below). This shows that Kandula's movements are concentrated within the forest patch; however he also frequents agricultural plots in the surrounding areas.
By separating the data into the two main seasons, wet and dry, the timing of this behavior becomes clearer. In the wet season, when farmers are planting and growing their crops, Kandula restricts his movements to forested areas and his range is small. In the dry months Kandula expands his range to take advantage of forage available in the abandoned fields.
Another interesting result was obtained through observing each of the six time intervals of location data for each day. As you can see in the maps below, Kandula spends much of the daylight hours (10 a.m. to 6 p.m.) under the cover of the forest. The canopy cover of the forest provides shade from the sun, and also a retreat from human activity. As the evening progresses and the temperature cools, Kandula begins to spend more time foraging in the open agricultural areas.
Click on each map to enlarge.
Such data provide critical information to wildlife managers in assessing the needs and preferences of the elephants. By observing foraging patterns of wild elephants, potential human-elephant conflicts may be identified so that appropriate mitigation measures can be taken in advance. By preventing conflicts, the welfare of both humans and elephants can be protected.