Fortunately, we have two independent studies on the topic as to whether ultrasonic cat deterrent devices (‘cat repellers’) work and therefore I able to provide a fairly definitive answer to the question in the title. Before I do it’s come to my attention that these cat deterrents can be heard by some people, particularly younger people. There is a story online as I type this from a woman on the mumsnet.com website who says that her neighbours have fitted an ultrasonic cat deterrent and she can hear it which is very troubling for her. She commented:
“For the past few weeks I’ve been hearing a really high-pitched sound while in my garden. It’s very shrill and has made sitting outside in the sun really uncomfortable because it’s like a needle feeling in my ears. It’s coming from various parts of my next-door neighbour’s garden, sometimes multiple bleeping at once.”
This should be known by people who are thinking of purchasing this device.
Ultrasonic deterrents reduce nuisance cat activity on suburban properties
The heading is the title to a study published in July 2018 on the Science Direct website. The conclusion was that “ultrasonic deterrents reduced the frequency of incursions into gardens by resident cats by 46% while the duration of incursions was reduced by 78%. What they called “peripheral cats” were unaffected by the ultrasonic device. I interpret that to mean cats that were the least active during the two weeks before the device was turned on. The gender of the cat did not have any bearing on the outcome. The device affected owned cats more effectively than unowned cats. In all, 78 cats participated in the study. They were detected in 17 of 18 surveyed gardens. Almost 53% of the cats were domestic cats living nearby.
They tested the effectiveness of a couple of ultrasonic devices, namely CatStop© and On-Guard Mega-Sonic Cat Repeller©.
This study was conducted in Australia by scientists at the Environment and Conservation Sciences Cluster, School of Veterinary and Life Sciences, Murdoch University, 6150, Western Australia, Australia. By and large, Australian scientists have a negative viewpoint about wandering domestic cat.
The efficacy of an ultrasonic cat deterrent
The title is that of the second study that I want to refer to which was published in January 2006 on the Science Direct website. The study was carried out by the RSPB, The Lodge, Sandy, Bedfordshire SG19 2DL, UK.
They tested the “efficacy of an ultrasonic cat deterrent ‘Catwatch©’, using 63 and 96 volunteer observers in two long-running (18 and 33 weeks) blind experiments”.
The concluded that the device had “a moderate deterrent effect, reducing the probability of a cat intrusion into a garden by approximately 32% in the first experiment but not in the second. The average duration of intrusions was reduced by approximately 38 and 22% in the 2 experiments respectively.”
They commented that the advice might have been more effective if it had been positioned “more carefully with regard to entry points to the garden that are regularly used by cats.”
We can see that ultrasonic cat deterrents are partially or moderately effective. This is about what I would have expected. In fact, the results are slightly better than I would have expected. They may displease gardeners who want to totally ban neighbouring cats wandering into the garden but I would suggest that these devices are effective enough to purchase to which they might add other deterrents. The water sprayer although activated by a motion sensor detecting the wandering cat can also be effective to a certain extent.
However, I don’t think that it is possible to completely deter outside domestic cats from wandering into your garden unless you build a fence around which is high enough with an overhang which is large enough to provide a fully effective physical barrier.
Below are some more pages on cat deterrents.