Ever attempted to take a walk to escape the hubbub of modern life, only to be assaulted by birdsong that sounds uncannily like a ring tone or car alarm? You’re not alone. Here’s why it’s happening – and why it’s a concern.
There I was, walking my dog on a crisp Monday morning at the local park. The sky was slowly beginning to change from black to a dark shade of purple. As I wandered through the dew-covered grass, I heard a familiar yet eerily unnatural sound. It was a car alarm, yet it wasn’t – it was actually a bird mimicking a car alarm.
This wasn’t the first time I had heard birds making this sound – I had noticed the birdsong around me was sounding bizarrely artificial on several occasions previously. Usually, I dismiss the sounds as a strange indictment of humanity’s encroachment on the natural world – but this time, I wanted to know more. Am I crazy? Is this a glitch in the matrix? Why do birds make these sounds and does it serve a purpose beyond reminding us humans of our detrimental impact on nature’s beauty? I had to find answers.
“It’s well known that birds are incredible mimics,” says Kristal Cain, associate professor in animal behaviour at the School of Biological Sciences at the University of Auckland. “Because they are so common in urban areas, and are such great mimics, they will commonly pick up noises like doorbells, car alarms, and squeaky bike brakes.”
Birds imitating things like car alarms and ringtones is a relatively new behaviour, though their talent for mimicking human-made sounds has been observed for centuries. Though we often think of parrots as being the “talking” birds, many other species in Aotearoa have the ability to mimic sounds – though perhaps none more well recognised than the tūī. Part of the songbird or passerine suborder of birds, tūī are known for having two voice boxes and producing a wide range of complex and varied sounds, including mimicking other birds and even human speech. Myna and starling birds also have mimicry abilities, which, alongside attracting potential mates, can be used to ward off predators, secure resources or communicate with other birds.
“The idea is that it’s quite expensive,” says Cain. “And whenever we see really expensive things in the animal world, usually it’s because they’re showing off.”
The “expensive” thing Cain is referring to is the brain capacity used by birds to remember the noises they hear and then recreate them. Effectively, birds are recreating sounds to flaunt how big their brains are to potential mates. “They’re kind of showing that they’re a quite high-quality individual that can waste energy on having this big brain that memorises all this different stuff,” Cain says. The older the bird, the more sounds it can make and the more attractive it becomes to the opposite sex.
Unsurprisingly, birds in urban areas are more likely to imitate human-made sounds, while those in rural settings are more likely to imitate other birds. “It’s just about what they’re hearing and how often they’re hearing it,” says Cain. Another factor at play is if there are better noises to mimic. Although anecdotal, some research suggests that in places where there are no korimako for them to mimic – such as the Chatham Islands – the tūī song is very different to those living in areas with high populations of korimako.
While there isn’t enough research to definitively state whether or not intergenerational transmission of human-made sounds is occurring in birds, experts such as Cain acknowledge there is a risk of birdsong changing over time as generations grow up hearing different sounds. In Australia, the phenomenon is beginning to have a damaging effect on bird populations – leaving some at risk of extinction. The regent honeyeater is a critically endangered bird endemic to southeastern Australia. In fact, they’re so endangered that the males are growing up not hearing enough of their own call, which is in turn leading to them not being able to attract a female to mate. In Aotearoa, research has shown that when a female tūī was given a choice between a potential mate from the country or the city, the country tūī was the preferred mating partner.
“That cultural transmission can be really important for a species. It’s probably not so important for a species like a tūī, because they’re doing really well, but for some of these more threatened species it can be a big issue,” Cain says.
Interestingly, the topic of intergenerational transmission of these sounds between birds and their offspring hasn’t been widely studied. That means here in New Zealand, experts aren’t really certain about the wider implications of birds mimicking modern sounds. What we do know is that with the extinction of the huia, the tūī came to rule the dawn chorus. With a large number of tūī now mimicking car alarms, it might not be long before their once sweet serenade turns into a cacophony of horns and sirens.
