Remote Cameras Reveal Wildlife Movements in Northern Kenya
Dr. Zeke Davidson, Marwell Wildlife
Geoffrey Chege MSc., Lewa Research Department
An exciting project is underway in Northern Kenya: remotely triggered infra-red camera traps are being used to monitor the movement of wildlife on Lewa Wildlife Conservancy just north of Mt Kenya. Lewa has been at the centre of Marwell’s field conservation work in Kenya since the 1990’s.
The cameras operate around the clock and take high-resolution photographs at night using infrared flash technology. The cameras are placed on either side of a 30m gap in Lewa's 140 kilometre long protective game fence. The traps are housed in defensive metal boxes and surrounded by high voltage electric wires to deter inquisitive elephants from “investigating”.
The idea is to photograph both sides of animals passing through the gap. In this way we are able to identify individuals and get an idea of which animals are using the gap regularly. Animals with distinctive coat patterns, such as leopard, giraffe and Grevy’s zebra are the easiest to monitor. Coat patterns are unique and so provide a reliable tool for identification. It is possible to identify less distinctive animals based on body markings such as scars, ear notches and tears and in the case of lions, whisker spots are sometimes visible enough to note their unique spot patterns.
Data collected from the cameras is already enhancing and furthering our understanding about the types and numbers of wildlife species that pass through the gap. Preliminary results have shown that traffic of giraffe and plains zebra moving out of Lewa in the evenings, return again in the early hours of the following morning. This might suggest that these animals have particular foraging sites or water sources outside Lewa that they can’t access during daylight. Perhaps this is due to the movement of herds of livestock or the presence of pastoral farmers in the area. The movement itself is interesting because it means that animals are able to access resources away from the conservancy and spread the load of grazing pressure on Lewa itself.
Understanding why animals move between a conservancy like Lewa and open rangelands is important for their protection and conservation. One of the main reasons for installing the cameras was to detect movements of the highly endangered Grevy’s zebra through the fence gap. Beyond the gap lies state land managed by the Livestock Marketing Department (LMD). Wildlife is vulnerable in this area due to a lack of protection and high human population density. On one occasion, the evening of the 16th of December 2009, we captured an injured male Grevy’s zebra leaving the conservancy. His wound appeared to have been caused either in a fight with another zebra or by a predator. The zebra spent approximately 30 hours out in the LMD land and returned the following evening. Where he went, and why, remain a mystery. But we do know that the injury was caused outside of Lewa's protective fence. We now need to turn our attention to what might be attracting some animals out on nightly forays into potentially more risky areas. Looking at the daylight photograph of the zebra below, one notices a distinct line marking the landscape and running perpendicularly away from the camera. This marks the Lewa fence line, and the change in vegetation between the conservancy and the neighbouring LMD land. There is a clear difference in the vegetation type between the two areas and this may support the suggestion that animals moving out of the conservancy are accessing a different type of forage not available within the Conservancy.
Many species appear to be using the gap regularly, not least of these are the large carnivores; hyena, lion and leopard. When large carnivores like lions leave a protected area such as Lewa, this may be a warning sign. There is a high risk that they will come into conflict with pastoral communities and prey upon their stock animals. This type of movement has been recorded by our cameras on two occasion, and is useful information when considering ways to mitigate conflict. It may be possible to use camera trap data to warn local communities that lions are in the vicinity so that they can take extra precautions for their own and their livestock’s safety. Such measures could be critical in mitigating human wildlife conflict, and reducing the numbers of lions and many other carrion eating species killed in retaliation for stock depredation.
We will continue to monitor the fence gap for some time to come. In time we might be able to determine the extent to which the Lewa Wildlife Conservancy acts as a source of wildlife for her neighbours and provide helpful insights into the protection, conservation and management of highly endangered species like the Grevy’s zebra.