Eyes in the back of your herd: painting artificial eyespots on the rear-ends of cattle reduces predation by large carnivores

Herds of cattle are a common sight when driving through the countryside, grazing on an abundance of green grass, unaware of their potential fate as a Sunday roast centrepiece. They have it easy compared with their African counterparts, which have some fearsome predators to contend with. Lions, leopards and cheetahs stalk the grazing pastures of many livestock herds in these regions, an inevitability when agriculture breaches natural habitats.

Protecting livestock from large mammalian predators often involves lethal control, which is reducing the numbers in carnivore populations at a concerning rate. It is vital that we are able to balance the protection of these predator species with the preservation of the livelihoods and traditional practices of farmers.

A new study published in Nature, led by Dr Neil Jordan, suggests that a simple, inexpensive intervention could keep cattle safe from large carnivores. The study found that painting artificial eyes on a cow’s rear-end proved effective at preventing attacks by ambush predators over a four-year period. The strategy was so effective in fact, that none of the cattle sporting these painted peepers were killed by predators for the duration of the study. By contrast, 15 unpainted control group cows were killed by lions or leopards. Considering that the cattle chosen for the study roamed in high-predation areas, this is an impressive result.

Interestingly, the researchers also monitored a third group, along with the eyespot marked and unmarked cows. These had simple black crosses painted onto them, in place of the eyespots. Encouragingly, this technique also reduced the number of attacks on these cattle, and only 4 of the cross-marked cattle were killed during the study. Whilst not as effective as the eyespots, these cross-marked cows stilled fared better than the unmarked cows. This is good news for those farmers who may have trouble recreating detailed eyespots on their herds.

Whilst this is the first study of its kind to demonstrate that artificial eyespots can reduce predation by large mammals, this method of anti-predation is not novel in nature. Plenty of examples exist of organisms evolving eye-like patterns, consisting of concentric circles, to deter predators. The most obvious examples are found in many butterfly and moth species. Nevertheless, scientists haven’t pinned down the exact mechanism by which these symbolic eyes prevent predation.

A number of hypothesis exist and were considered by the researchers to explain the study’s findings. They argued that the most compelling were the ‘detection’ and ‘conspicuousness’ hypotheses. The former means that the attack was prevented because the eyespots tricked the predator into thinking it had been spotted; for ambush predators, the element of surprise is an important part of their hunting tactics. However, this hypothesis wouldn’t explain how the cross-marked cattle had some success at deterring predators. This is where the latter hypothesis might explain what’s going on. Markings such as crosses and eyespots are highly visible and could seek to confuse the predator by presenting their usual cattle prey as a creature they don’t recognise or haven’t encountered before. The novelty of this eye-spotted or cross-marked cow could cause the predator to hesitate or abort their attack altogether, in case this strange four-eyed creature proves to be dangerous.

The researchers warn that their findings don’t provide definitive proof for any of the hypotheses, but it is very possible that the anti-predation effects can be attributed to a combination of the proposed mechanisms. They also caution that the predators may become habituated to the artificial markings on the cattle, and no longer see them as a threat or deterrent. To avoid or stave off habituation, the researchers suggest painting the cattle periodically ─ only when predation levels are high ─ and using a combination of both cross-marked and eyespot-marked cattle in any given herd.

Nevertheless, the results mean that farmers tending livestock in these heavily predated regions can access an effective, low-cost, anti-predation method that saves the lives of their cattle and predators alike. Implementing non-lethal methods of predator control is becoming increasingly important as human territories continue to expand onto the natural habitats of endangered big cats and other large mammals.

Sources

1) Radford C, McNutt JW, Rogers T, Maslen B and Jordan, N. Artificial eyespots on cattle reduce predation by large carnivores. Commun Biol. 2020 Aug, 3:430. https://doi.org/10.1038/s42003-020-01156-0

2) Bruskotter JT, Vucetich JA, Manfredo MJ, Karns GR, Wolf C, Ard K, Carter NH, Lopez-Bao JV, Chapron G, Gehrt, SD and Ripple WJ. Modernization, Risk, and Conservation of the World’s Largest Carnivores. BioScience. 2020 July, 67:7, 646-655, https://doi.org/10.1093/biosci/bix049

3) Image curtesy of Theme Inn from unsplash.com (https://unsplash.com/photos/RCpjrS0ML0k)

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