CHIÈVRES, Belgium -- The COVID-19 pandemic has had a massive impact on our lives and has brought about a huge reduction in industrial and social activity. One positive side-effect of the imposed lockdowns has been reduced levels of air pollution due to decreased human activity. Other examples of positive environmental impacts that have been featured in the media include the water becoming clearer in Venetian canals and wildlife entering urban areas.One recent change is audible rather than visible: the acoustic environments of our cities have temporarily changed. With so many people staying at home, there is significantly less noise from cars, buses, airplanes, trains and other forms of transportation.Many people on Twitter have been wondering if “birds are louder” now lockdowns are in effect. Questions include: Are the birds singing more, are they louder, or am I just imagining it?It is true that in the northern hemisphere, migration occurs in spring, with summer visitors arriving from the south, and it is very common to see and hear more birds at this time of year. This is also the breeding season, when birds become more vocal, singing to attract a mate or to defend their territory. Due to the reduced noise pollution we’re currently experiencing, it is also easier to hear this seasonal increase in chirps, trills and squawks. A genuine wonder of nature. Have you already noticed more birdsong this year?Of course, the reduction in noise doesn’t just mean that we humans can hear the birds more clearly. More importantly, it means that they can hear each other! Noise pollution is known to cause stress in birds. Birds use songs and calls to communicate, not just for reasons related to breeding, but also to warn other birds of danger and chase away predators, or just to communicate with their neighbors. If this communication must compete with the high levels of noise in the cities, the birds are forced to communicate at higher frequencies, or simply louder. This can use up energy that is needed to feed, fly and protect their territory. If too much interference occurs, they may also be unable to receive warning calls from other birds and become more vulnerable to predation.Use the current time to enjoy the birdsong in your garden or around your home, learn to recognize different birds by their calls, and discover what your environment could really sound like with less ambient noise. If you want to enjoy birdsong while on a walk, please remember that social distancing rules still apply, that you can only be accompanied by one person not living at the same address, picnicking and casual resting are prohibited, and transportation to a nature area by car is considered nonessential travel (except when accompanied by small children or the elderly). But there are still plenty of opportunities to see, and hear, birds without traveling far from your home. Why not take a walk in a nearby forest, park or rural area to enjoy the birds while their songs are the soundtrack of this lockdown?