A Scaredy-Cat Won’t Hunt

Story by Jack McGovan

In the streets of Christchurch, New Zealand, a breeze ruffles a pet cat’s fur as it saunters along a few blocks from home. He’s well-fed, but when a tantalizing aroma wafts by, he charts a course to the source. Hopping into a garden, the cat approaches a curious-looking vessel emitting a scent so yummy and strong that he … yelps and dashes away, spooked by the voice from an invisible human.

“In New Zealand,” says government wildlife ecologist Sze Wing Yiu, “roaming cats are a very big problem.” At least 40 percent of New Zealand households have a pet cat, and the feral population is likely in the millions. Globally, cats have contributed to the extinction of dozens of species, and they threaten hundreds more.

Looking to protect wild animals from feline attacks, Yiu and her colleagues have embarked on a cat-scaring crusade. In a 21-day experiment, the scientists dipped cotton balls in fish oil and hid them in tea infusers, dangling them in front of cameras at seven sites across Christchurch. Rigged to a timer and a speaker, their custom-built cat-scaring devices are designed to trigger 10 seconds after a cat crosses the camera’s path, giving the feline an ungodly fright and sending it fleeing for a safer snack.

In their garden experiments, Yiu and her team found that more than 40 percent of the startled cats abandoned their hunt, and a quarter were so spooked they never returned to the site. Interestingly, and perhaps predictably, the researchers had even greater success when they tried terrifying feral rural cats they had captured and put in pens. Those rural cats were more easily frightened than their urban peers—Yiu’s recordings got 66 percent of them to stay away from the only food sources in their pen. To Yiu this makes sense, as city cats are likely more used to, and hence less scared of, human-sounding voices.

Ultimately, Yiu hopes her recording set-up can be used to protect birds. In recent experiments, which have not yet been written up in a scientific paper, Yiu and her team took their apparatuses to four urban reserves that support threatened bird species where they were hoping to find out whether a series of speakers can depress cat activity over a broad area. 

Bill Lynn, who studies animal ethics at Clark University in Massachusetts, acknowledges the existing scientific research showing cats are damaging to wildlife in specific environments. But, he believes cats are being unfairly demonized at a larger scale. He says people’s harsh assessment of cats goes beyond what the data supports. “People have it strongly in their minds that cats don’t belong,” he says.

Nonetheless, given the well-documented history of cats hurting wildlife in specific settings, he says Yiu and her colleagues’ project helps highlight a possible solution to keeping problem populations in check.

The idea behind Yiu’s feline frightener stems from a developing scientific field called fear ecology. Since most species have predators, and animals are scared of their predators, scientists are learning to manipulate problem animals through their fear, rather than with more aggressive control methods like hunting, killing, trapping, or relocating.

For instance, more than a decade ago Justin Suraci, now a senior scientist at the California-based Conservation Science Partners, showed that he could use recordings of dogs barking to scare island-dwelling raccoons away from the intertidal areas they were overgrazing.

“I had, admittedly, never really thought about the management applications of it,” Suraci says. “It was all about fundamental ecology in my head.”

In the years since Suraci’s experiments with racoons, scientists have increasingly realized the conservation power of fear. In another of his experiments, published in 2017, Suraci and his colleagues showed they can use recordings of human voices to scare pumas away from feeding sites in the Santa Cruz Mountains of Central California. A 2022 paper by a different team showed a similar result with ungulates in Sweden.

Eventually, says Yiu, the cats in her experiment got used to the recordings, so her alarm system won’t work as a long-term solution. It would likely be “most effective if you only deploy it for a short period of time,” she says, such as “during bird breeding season and around bird breeding sites.”

There are also concerns about whether the device disrupts other animals, including the very birds researchers want to protect. There’s also the issue of dealing with the cats that either get used to the deterrent or weren’t scared in the first place. Yiu suggests that a future study—in which she and her colleagues mix other sounds like cat meows and dog barks in among the human calls—could help them explore that concern.