A leopard is caught on camera crossing the fence surrounding Lake Nakuru National Park in Kenya. Credit: Christine Wilkinson, Funded by the National Geographic Society.
Are conservation fences effective?
Beginning largely in 2013 with the publication of two conflicting papers about the effectiveness of conserving African lions (Panthera leo) in fenced ecosystems, the debate over fencing for conservation has been in full effect. The first 2013 study found that conserving lions in fenced reserves is cost-effective and sustainable, while the rebuttal studied the same lion populations and found the opposite: that more lions could be conserved per dollar in unfenced reserves.
Since then, several studies have attempted to classify both the costs of fencing reserves (such as range and migration disruptions, reduced connectivity, genetic consequences, and socio-economic costs) and the benefits (such as reduced poaching and human-wildlife conflict, reduced habitat encroachment, and streamlined population management). These studies have encouraged researchers and managers to systematically quantify these costs and benefits.
For my current research within and around Lake Nakuru National Park in Kenya, I am adding another perspective to this conversation. Lake Nakuru National Park is one of only two fully fenced national parks in Kenya (besides Aberdare National Park). The park is ~183 km2 and surrounded by a ~3m tall parallel-wire electric fence. Along some stretches, particularly areas abutting the fast-growing city of Nakuru, the fence has an additional woven wire mesh extending 1m into the ground to prevent wildlife from digging their way out. As a component of my work on human-carnivore conflict and carnivore movement, I set out to determine how effective the fence is, which wildlife are moving in and out of the park, and what implications this might have for wildlife behavior and connectivity in and around the national park.
Perimeter fencing around Lake Nakuru National Park in Kenya. Credit: Christine Wilkinson, Funded by the National Geographic Society
It quickly became clear that the fence is facing challenges in fulfilling its intended purpose. Along with my team of Kenya Wildlife Service staff (Christine Chepkisich) and rangers, as well as two master’s students from Egerton University (Gerald Osuka and Christine Chepngeno), I walked, jogged, and drove around the perimeter fence and discovered more than 170 points where animals were clearly crossing. We placed camera traps at 19 sites where there were signs of carnivores crossing, and monitored the cameras for a year.
So far we’ve seen an extraordinarily high amount of wildlife visiting the fence per trap night. Many carnivores are crossing every night, particularly spotted hyenas (Crocuta crocuta), leopards (Panthera pardus pardus), black-backed jackals (Canis mesomelas), striped hyenas (Hyaena hyaena) servals, (Letpailurus serval), caracals (Caracal caracal), and genets (Genetta genetta). Lions also visit and cross sporadically. Ungulates, primates, and even domestic animals routinely cross in and out of the national park.
A hyena is caught on camera crossing the fence surrounding Lake Nakuru National Park in Kenya. Credit: Christine Wilkinson, Funded by the National Geographic Society
On several of the cameras, I observed fence maintenance – for example, a national park employee placing boulders in the hole dug under the fence or moving components of the fence back into place. Yet, on each of these occasions the wildlife were able to easily find a way through the fence that very same night, by digging in or near the previous hole, pushing aside the rocks and boulders, or otherwise countering the maintenance effort.
What does all of this tell us? Wildlife are easily finding their way into the human communities. People and their livestock are able to enter the park (though uncommonly), and maintenance is infrequent. With one-third of the park’s area composed of a shallow alkaline lake, it may not be large enough to sustain its populations of wide-ranging large carnivores and other wildlife, which could be one reason why they’re seeking to roam.
Though the debate over conservation fencing will always be context-dependent, this study, which is the first to look at long-term large mammal behavior at a conservation fence, will add a fine-scale behavioral perspective as conservationists seek the best solutions for wildlife management and landscape connectivity in a changing world.
Resources
Creel, S., Becker, M.S., Durant, S.M., M’soka, J., Matandiko, W., Dickman, A.J., Christianson, D., Dröge, E., Mweetwa, T., Pettorelli, N. and Rosenblatt, E. 2013. Conserving large populations of lions–the argument for fences has holes. Ecology Letters 16(11): 1413-e3.
Durant, S.M., Becker, M.S., Creel, S., Bashir, S., Dickman, A.J., Beudels‐Jamar, R.C., Lichtenfeld, L., Hilborn, R., Wall, J., Wittemyer, G. and Badamjav, L. 2015. Developing fencing policies for dryland ecosystems. Journal of Applied Ecology 52(3): 544-551.
Packer, C., Loveridge, A., Canney, S., Caro, T., Garnett, S.T., Pfeifer, M., Zander, K.K., Swanson, A., MacNulty, D., Balme, G. and Bauer, H. 2013. Conserving large carnivores: dollars and fence. Ecology Letters 16(5): 635-641.
