Good fences make good neighbors (with carnivores)

(Press-News.org) A predator’s gotta eat, but sometimes what they eat harms people sharing the landscape, and that often leads to the carnivore’s death.  

Fortified corrals are one strategy used in Tanzania to protect both livestock and vulnerable carnivore species. But then where do lions, leopards and hyenas go for dinner? Do they feed on the next herd over?  

A new study led by Colorado State University has found that good fences truly do make good neighbors because fortified enclosures also benefit livestock keepers who live nearby. Instead of dining on easier meals next-door and negatively impacting neighbors who don’t have fortified enclosures, predators seem to completely avoid neighborhoods when some corrals are built from chain-link fencing, which is more effective than traditional African boma fences made of thorny bushes.  

These surprising results are the first to demonstrate a beneficial spillover effect from a strategy to reduce conflict with large carnivores, which play an important role in ecosystems. Losing apex predators can cause ripple effects that disrupt the food web and impact environmental health. 

“Coexistence between humans and carnivores is a global challenge, and conflict resulting from carnivores attacking livestock is among the most important coexistence threats globally, including here in the Rocky Mountain West and Colorado specifically,” said Kevin Crooks, co-author of the study and director of the CSU Center for Human-Carnivore Coexistence. “Our results provide important evidence of the effectiveness of proactive, non-lethal tools to prevent livestock predation by carnivores, benefiting not just the target household but potentially neighboring households as well.”   

Lead author Jonathan Salerno, an associate professor in CSU's Department of Human Dimensions of Natural Resources, said that while the intervention method studied is only applicable in limited contexts in the U.S. West, the need to understand the complex interactions among predators, people and conflict interventions is universal. 

"Understanding these dynamics can help guide effective use of conservation resources and support better outcomes for people, livestock and threatened species," he added. 

Chain-link linked to safety, savings  In a previous study published in January, Salerno and his collaborators showed that chain-link corrals reduced predation on cattle, goats and sheep in an area surrounding Ruaha National Park in southern Tanzania, a critical landscape for large carnivore conservation. In this agropastoralist system, livestock are kept in fenced compounds at night, when predators are active, and are herded to community grazing lands during the day.   

The park and surrounding conservation areas protect 10% of the world’s African lions, among other carnivores, but each household bordering the park has about a 30% chance of losing one or more of its animals to predation each year, a significant economic loss for these small-scale farmers.

Conservation organization Lion Landscapes subsidized 75% of the cost of fortified enclosures for livestock keepers near the park who chose to implement the intervention and cover the remaining 25% of construction costs. A cost-benefit analysis published in the paper showed that after just five years, the benefits from preventing livestock deaths were three to seven times greater than the amounts paid by livestock owners. 

"The break-even point is anywhere from three months to two years, given that the loss of one cow is a substantial amount of wealth,” Salerno said. “So, you reduce the risk enough that the fortified enclosure actually pays for itself relatively quickly.” 

Using monthly data from 758 livestock-keeping households from 2010 to 2016, the first study also found that the chain-link corrals were 94% effective at reducing the risk of predation in the short term and 60% effective in the long term.  

Beneficial spillover effect The new study, published March 6 in Conservation Letters, examined 25,000 monthly reports from livestock keepers and found that households neighboring those with chain-link corrals also reported fewer attacks on their livestock, the first time a beneficial spillover effect has been demonstrated. The study used data collected by Lion Landscapes and was funded by CSU’s School of Global Environmental Sustainability. 

“This research provides scientific evidence about the effectiveness of antipredation interventions, which not only reduce livestock losses but also have positive spillover effects, fostering coexistence between humans and carnivores,” said co-author Joseph Francis Kaduma, a research manager with Lion Landscapes. “By demonstrating how non-lethal methods can benefit both people and wildlife, the study offers practical conservation solutions that can be scaled to other regions facing similar conflicts worldwide.” 

Why are the carnivores staying away?  While the study does not answer this question, Salerno said that it’s possible the neighborhoods with enclosures are just too much work for predators.  

“The neighborhood with three or four enclosures is going to represent more risk or more effort for the carnivore, because they know they can't pull livestock out of the fortified enclosures, though a few leopards will try with a goat or sheep,” he said. “It reduces the availability; the night-time livestock buffet is simply less accessible and attractive.” 

Why not fence the park?  Like many national parks, Ruaha National Park is vast, and it’s not feasible to enclose it within a chain-link fence. Fencing the park also would have negative ecological consequences by isolating wildlife, and shutting people out would create even greater conflict between nearby communities and conservation interests, Salerno said. 

Case study for a global issue  Lion Landscapes has long-term relationships with local livestock keepers and diligently tracked the data that supported these studies. Salerno said that having this kind of data from other places would help conservation organizations and wildlife managers find solutions to similar conflicts.   

“If we gather these data, we can understand what factors are contributing to predation events on a particular ranch, and by accounting for the complexity of the larger system, we can start to understand what methods are going to be effective,” he added.  

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