Birds have extremely sensitive hearing that allows them to detect sounds at much higher frequencies than humans can. Some devices have been developed that emit ultrasonic sounds in an effort to repel nuisance birds from areas like airports, farms, and gardens. But do these ultrasonic bird repellers actually work? Let’s take a look at the evidence.
How bird hearing compares to human hearing
Human hearing range is generally considered to be between 20 Hz to 20,000 Hz. The average adult can’t hear sounds above 16-18,000 Hz. Birds, on the other hand, can hear frequencies up to and beyond 20,000 Hz depending on the species. Many birds can detect sounds in the ultrasonic range from 25,000 to 30,000 Hz. So birds can hear many sounds that are simply beyond our range of hearing.
Species | Hearing Range (Hz) |
---|---|
Humans | 20 – 20,000 |
Birds (average) | 20 – 20,000+ |
Owls | 50 – 24,000 |
Swifts | 100 – 20,000 |
Birds like owls and swifts with their specialized ear structure and hunting needs have evolved incredibly sensitive hearing capable of detecting minute sounds made by prey. But even backyard birds like sparrows can hear sounds up to about 15,000 Hz, surpassing human capability.
How ultrasonic bird repellers are supposed to work
Ultrasonic pest repellers advertise themselves as an effective, humane way to be rid of bothersome birds. They emit high-frequency sounds, usually ranging from 20,000 Hz to 60,000 Hz, that aim to annoy and frighten birds away.
Manufacturers claim these sounds are unpleasant and cause discomfort for birds but are inaudible to humans. Some ultrasonic devices randomly alternate between different frequencies while others use “sweep technology” rapidly changing from one ultrasonic frequency to another. The random or unpredictable nature of the sounds is said to enhance their effectiveness.
Potential problems with ultrasonic repellers
However, there are some issues with the claims made by ultrasonic bird repeller manufacturers:
- Just because humans can’t hear the ultrasonic sounds doesn’t mean birds necessarily find them bothersome. Birds vocalize to each other using sounds in the ultrasonic spectrum.
- Birds may rapidly acclimate or habituate to regular ultrasonic sounds meaning the repelling effect diminishes over time.
- Sounds need to be emitted at high enough volumes to actually cause irritation or discomfort. Small ultrasonic devices may not be powerful enough.
- High-frequency sounds quickly diminish in intensity over distance. So ultrasonic output needs to be strong enough to work over the intended range.
Scientific research on ultrasonic bird deterrents
Controlled scientific testing is needed to evaluate whether a bird deterrent method like ultrasonic sound actually works. Unfortunately, there’s something of a disconnect between manufacturers’ claims about their ultrasonic products and what researchers have found when putting them to the test.
Laboratory findings
Scientists have tested birds’ reactions to ultrasonic frequencies in laboratory conditions. Results showed that European starlings didn’t react to sounds up to 50,000 Hz. Even sounds at 80,000 Hz didn’t faze the birds or stop them from feeding unless the volume was extremely loud. Pigeons also showed little response to various ultrasonic frequencies and mostly just got accustomed to the noise.
Field research conclusions
When ultrasonic repellers have been studied outside the lab in real-world settings, they have mostly proven ineffective:
- One study of ultrasonic devices tested on Canadian geese found they provided no deterrent effect with the geese quickly habituating to the high-frequency sounds.
- Research installing ultrasonic repellers at blueberry farms saw no difference in bird activity or crop damage compared to control sites.
- A study testing four commercial ultrasonic repellers on crows observed no lasting impact on crow presence or numbers around sites with active repellers.
Many field studies have similarly found little benefit to using ultrasonic frequencies to repel pest bird species like starlings, sparrows, crows, wood pigeons, and waterfowl.
Alternative bird deterrent options
While ultrasonic sounds may not be very effective, there are some other options to try to humanely deter birds:
- Visual deterrents like scarecrows, predator decoys (like plastic owls), flutter ribbons, and reflective tape can frighten some species of birds.
- Physical barriers like netting or bird spikes prevent birds from roosting or nesting in unwanted areas.
- Repellent gel products create a sticky, uncomfortable surface that deters birds from landing.
For a serious bird problem, seeking professional advice can help identify effective solutions suited to the particular species and situation.
Conclusion
Despite what ultrasonic bird repeller manufacturers may claim, scientific testing indicates these devices are largely ineffective. The high-frequency sounds they emit generally don’t disturb birds enough to scare them away from an area unless played at extremely loud volumes impractical for normal use. Birds also rapidly get used to ultrasonic noises meaning any impact is very short-lived. Physical deterrents or barrier methods tend to work better if trying to humanely keep birds away from a specific location like a building ledge or garden.