Birds not ’emu-sed’ by urban traffic noise
Hands up if you’ve been woken earlier than expected by noisy peak-hour traffic outside your window? Honks, screeches, trucks, angry drivers hurling profanities at the driver in front…ah I can hear it now. Imagine if when you finally dragged yourself out of bed to go and have a chat with your housemates, that noise was so loud you couldn’t hear each other speak. Not only did you wake up early, but now the noise hinders your ability to communicate effectively. Sounds annoying, right? This is what’s happening to birds living in urban environments. Those honks and screeches and angry driver profanities are happening smack bang at the MOST important time of the day that birds sing.
Why do birds sing?
We’ve all heard the diversity of bird calls, from the cheeky Kookaburra who laughs at us all day long, to the gentle ‘tweet tweet’ of the Willie Wagtail. Birds are one of many types of animals that rely heavily on communicating vocally. Why? Vocal signals can travel much further than other kinds, such as visual cues or smells. This allows birds to ‘talk’ to their feathery friends when they aren’t in sight. Different species of birds have unique songs allowing them to communicate with themselves and not be overheard by others, and to recognise if the song is comes from friend or foe.
The dawn chorus
One of the most important times of the day for many birds is dawn, when they spectacularly perform the dawn chorus. A choir of ‘tweets’ and whistles and caws, all trying to outcompete each other to be heard. The exact reason birds take part in this early morning singing practice is unknown. Some say it’s a chance to really show the other birds what you’ve got and ‘sing to impress’ in the hope of attracting a feathery lover. Others think the timing of the chorus is crucial to hunting and foraging success. Whatever the answer, there is no argument amongst bird enthusiasts that the dawn chorus a pivotal behaviour for our feathery friends.
The doom and gloom of urbanisation
It’s no secret that ripping apart natural landscapes to build concrete jungles is having negative impacts on the environment. We are drilled with the dire consequences of chemical pollution in particular, but what if the noise we make has repercussions we couldn’t have predicted. One of the noisiest times of the day in a city is ‘peak hour’. Amazingly, in the mornings this begins before dawn. I have no idea who goes to work BEFORE the sunrise? But apparently, it’s true. Let’s think back…what else happens at dawn? Bingo. The dawn chorus. This incredibly loud chorus of cars, trucks and trains outcompetes those bird tweets, chirps and whistles, imposing on their ability to attract a mate or forage for a feed.
Even though this competition occurs every morning, there are still loads of birds that find home in urban parks, in and around the city. They must adjust something about their song to reduce the competition.
Bird songs generally comprise of three components:
Frequency – relating to the pitch
Amplitude – relating to the volume or loudness
Timing – relating to, you guessed it, the timing of the song
Many researchers suggest they could sing either louder, at a higher pitch, at a different time, or a combination. Each option comes with its ups and downs, but whatever they’re doing, it must be working. For species that can’t make a change though, they might not survive the city life, posing a multitude of conservation and management issues to tackle.