Have you ever been sitting around a campfire on an inky black night, only to see dark shapes flitting overhead? Those eerie apparitions are quite likely to be bats. Nocturnal mammals like bats don't rely on eyesight to find their way around but navigate using a form of sonar called echolocation. This means they hunt at night with impunity, not in the least disabled by not being able to 'see' with their eyes, where they are flying.
How does the dog by your side react? They seem unsettled, perhaps glancing up from time to time to stare into the dark. They may be restless and perhaps give the odd, hesitant "Woof". Why is this? Are they hearing the echolocation noises made by bats or are they merely disturbed by the flickering shapes in the darkness? Let's find out.
Signs Your Dog has Heard Bat Echolocation
Bats use high-frequency sound to find their way in the dark. Indeed bats use a range of frequencies, all of which are too high for humans to hear, but some are within range of dogs. How clearly the dog hears the sound depends on several factors including their age (how well or not they can hear), the frequency (wavelength) of the sound, and its volume. When all the factors align, the dog may show they've heard the bats by suddenly becoming alert.
Think of the dog startled by the doorbell, and the dog's reaction to hearing bat echolocation is likely to be the same. They may jump up and instantly be on high alert. It's likely their ears will prick up and scan from side to side in an attempt to pin down where the sound is coming from. In that way dogs do, they may also tilt their head, which, again, is a way of localizing the direction from which the sound is coming.
The dog may well be confused or even a little distressed by the sound. In the face of uncertainty, their hackles may rise, the tail may go stiff, and the dog could try a few barks to see if the source of the sound can be scared away. Some dogs may also pace or run around as if patrolling territory alert for threats. All in all, a dog hearing bat echolocation expresses a range of behaviors from confused to protective.
The History of Bat Echolocation
It's a tease, isn't it, wondering how something that we can't see and can't hear (ie a bat flying around at night) finds its way around. This is the puzzle that was solved in 1938 by two scientists, Griffin and Galambos, working in the field of neuroethology.
These two researchers worked out bats used echoes to detect insects and track them on the wing. The scientists devised a range of cunning experiments that showed that bats used pulsed-echoes not only to find their supper, but also to track it's distance and direction while flying on the wing.
From this, other workers discovered that different bat species use different frequencies and types of echo pulses to communicate. Indeed, the bats themselves have evolved special anatomy of the vocal folds to make high pitched clicks and ears to detect the answering echo.
The Science of Bat Echolocation Vs What Dogs Hear
Watch any war movie involving submarines and you'll be aware of sonar. This is where a sound wave is generated that travels through water and is reflected back by objects in its path. The sonar operator is able to recognize the size and distance of the object by the characteristics of the reflected (or echoed) sound wave.
Bats navigate using a similar system involving very high-frequency sound waves. Indeed, the frequencies bats use are too high for the human ear to hear. But bats don't just communicate using a few high-frequency wavelengths, they use a significant spectrum. Think of this like stations on a radio. As you 'tune' the radio, you are altering the frequency of the receiver to pick up radio stations broadcast on different wavelengths.
It just so happens that bats broadcast on a range of channels or frequencies too high for people to hear. But some of those frequencies do lie within the hearing range of dogs. In the same way that an AM radio won't pick up LW or FM signals, dogs are able to detect bat echolocation noises towards the lower end of bat vocabulary, but not in the higher frequencies.
Let's take a look at the numbers.
First, bats broadcast on frequencies ranging from 20 - 200 KHz
Compare that with human hearing, which dawdles along at a limited 2 - 20 KHz. Thus, human hearing drops off at around the same point that bats start communicating.
In contrast, dogs hear noises ranging from 6 - 70 KHz. This means there's an overlap with bats at frequencies between 20 - 70 KHz, which means a large part of bat echolocation (70 - 200KHz) is falls on deaf canine ears.
Training a Dog to Respond to High-Frequency Sounds
It's pretty impossible for a person to train a dog to hear high-frequency sounds that are generated at random (such as by a bat) which we can't hear. However, it's not impossible. The closest we can get is training a dog to respond to a silent dog whistle.
Silent dog whistles work by emitting sounds that are too high-pitched for the human ear to hear, and yet, are audible to dogs. Some trainers hold that silent whistles are excellent for dog training because they cut through the distracting noise of everyday life, giving the dog a 'clean' noise to respond to.
To train using a silent whistle, start by working in a distraction-free environment. Blow the whistle and attract the dog's attention with a treat. When they come to you, give plenty of praise - and the treat. As lessons continue, drop the hand signal and just use the whistle to get the dog's attention. The idea is that they learn to link the "silent" sound to getting a reward when they come to you.
Once the dog has learned this in a safe place, take training outdoors. Start in the yard, and practice the recall. If the dog is doing well, then visit the park. If you can't trust the dog's recall 100%, then consider keeping them on a long-line until their training is rock solid.
Written by Pippa Elliott
Veterinary reviewed by:
Published: 05/24/2018, edited: 04/06/2020