Published by ARSTECHNICA.COM
Summary generated on August 19, 2020
Cattle herds in the Okavango delta region in Botswana are plagued by attacks by lions and other predators, prompting farmers to retaliate by killing the predators.
An alternative nonlethal technique involves painting eyes on the butts of cattle to trick ambush predators like lions into thinking they've been spotted by their intended prey.
It's called the "Eye-Cow Project," and a recent paper published in the journal Communications Biology provides some solid empirical evidence for the practice.
There are now practical guides for using the "Eye-cow" technique available in both English and Setswana, so farmers can try it out for themselves.
Neil Jordan, a conservation biologist at the University of New South Wales in Australia, came up with the idea several years ago while he was doing field work in Botswana.
Local farmers killed a pair of lionesses in retaliation for preying on their herds of cattle, and Jordan wanted to come up with a non-lethal alternative.
The African lion population has dropped significantly from more than 100,000 in the 1990s to somewhere between 23,000 and 39,000 in 2016-much of it due to retaliation killings.
Jordan knew that butterfly wings sporting eye-like patterns are known to ward off preying birds, and are also found in certain fish, mollusks, amphibians and birds, although such patterns had not been observed in mammals.
He also discovered that woodcutters in Indian forests have been known to wear masks on the backs of their heads to discourage any tigers hunting for prey.
He had observed a lion stalking an impala, and noticed the predator gave up the chase when the prey spotted it.
Lions are ambush hunters, Jordan reasoned, and decided to test his "Detection hypothesis" that painting eyes on the butts of cows would discourage predatory behavior from the local lion population.
The Botswana Predator Conservation Trust agreed to work with Jordan on the project, along with a local farmer, for a ten-week pilot study.
Jordan and the farmer painted eyes on one-third of a herd of 62 cattle, and took a head count when the cattle returned to the fold each night to see how many had survived.
Only three cows were killed during that period, none of which had painted eyes on their butts.
Granted, it was a small sample size, but those results were encouraging enough to convince Jordan to conduct a more ambitious study over the last four years.
His team worked with local farmers in the Okavango delta region, painting the cattle in 14 herds.
They used acrylic paint, applied with foam stencils in the shapes of the inner and outer "Eye." The colors were chosen "Because of their highly contrasting and aposematic features, common in natural anti-predator signaling settings," the authors wrote.
Roughly one-third of the cattle in each herd got the eye patterns, one third got simple cross-marks, and one-third weren't painted at all.
The results confirmed Jordan's preliminary findings.
Cattle with the painted eyes on their rumps were significantly more likely to survive that those cattle that had crosses painted on their butts and those that weren't painted at all.
The authors were surprised to find that even the painted crosses offered some survival advantage over the unpainted cattle.
Over the course of the four-year study, 15 unpainted and four cross-painted cattle were killed by lions; none of the 683 cattle with painted eyes were killed.
"To our knowledge, our research is the first time eyespots have been shown to deter large mammalian predators," said co-author Cameron Radford, a graduate student at the University of South Wales.
"Previous work on mammal responses to eye patterns has generally supported the detection hypothesis. We think this may suggest the presence of an inherent response to eyes that could be exploited to modify behavior in practical situations, such as to prevent human-wildlife conflicts, and reduce criminal activity in humans."
First, Jordan acknowledged that there were always unmarked cattle in the herd for their experiments as controls-what he termed "Proverbial sacrificial lambs." It's not clear whether applying painted eyes to cow butts would be as effective if all the cows in the herd were painted.
He suggests that farmers apply the marks to the most valuable cattle in the herd as the best approach until future research can be done.
Second, there is the question of habituation: whether predators will eventually become accustomed to the painted eyes and learn to ignore it as a deterrent.
"Protecting livestock from wild carnivores-and carnivores themselves-is an important and complex issue that likely requires the application of a suite of tools, including practical and social interventions," said Jordan.
"The eye-cow technique is one of a number of tools that can prevent carnivore-livestock conflict. No single tool is likely to be a silver bullet. Indeed we need to do much better than a silver bullet if we are to ensure the successful coexistence of livestock and large carnivores. But we're hoping this simple, low-cost, non-lethal approach could reduce the costs of coexistence for those farmers bearing the brunt."