But our research is the first to investigate how multiple snake species respond to sounds in a space where they can move freely. We also used an accelerometer to detect whether the sounds produced ground vibrations. In this way we confirmed the snakes were indeed registering airborne sounds, and not just feeling ground vibrations.
Do snakes move toward or away from sound?Most of the snakes exhibited very different types of behaviours in sound trials compared to the control.
Woma pythons (Aspidites ramsayi) – a non-venomous snake found throughout Australia’s arid interior – significantly increased their movement in response to sound and actually approached it. They exhibited an interesting behaviour called “periscoping”, in which snakes raise the front third of their body in a manner that suggests curiosity.
In contrast, three other genera – Acanthophis (death adders), Oxyuranus (taipans) and Pseudonaja (brown snakes) – were more likely to move away from sound, signalling potential avoidance behaviour.
Death adders are ambush predators. They wait for their prey to come to them using the lure on their tail (which they wiggle to look like a worm), and they can’t travel quickly. So it makes sense they trended away from the sound. For them, survival means avoiding being trodden on by large vertebrates such as kangaroos, wombats or humans.
Brown snakes and taipans are active foragers that rapidly pursue their prey during the day. This means they may be vulnerable to daytime
predators such as raptors. In our experiments, both of these snakes appeared to have acute senses. Taipans in particular were likely to display defensive and cautious behaviours in response to sound.
Can snakes hear us?Our study further debunks the myth that snakes are deaf. They can hear – just not as well as you or I. Snakes can only hear low frequencies, roughly below the 600 Hz mark, whereas most of us can hear a much wider range. Snakes probably hear muffled versions of what we do.
So, can snakes hear us? The frequency of the human voice is about 100–250 Hz, depending on sex. The sounds we played in our trials included these frequencies, and were played at a distance of 1.2 metres from the snakes at 85 decibels. This is about the amplitude of a loud voice.
The snakes in our study responded to this sound, and many significantly so. So it’s probably safe to say snakes can hear people speaking loudly or screaming. That doesn’t mean they can’t hear someone talking (a normal conversation is about 60 decibels) – we just didn’t test sound at this noise level.