Hush! It’s Time to Save Quiet Nature
The honking of car horn warns passersby, a siren signals an emergency, a burglar alarm going off alerts people to a crime… Environmental sounds inform us of different situations in our daily lives. Animals in the wild, albeit without all these human technology and tools, also rely heavily on acoustic information - sometimes concerning matters of life and death. Through communicating with different sounds, animals are able to escape from predators, locate food and find their mates. However, urban noise is intruding into nature. It is causing great harm to the animal world without notice. A global movement of quiet emerges in response.
Fish, birds and frogs make special sounds for courting. The lengths and volumes of their calls directly affect their mating success rate. Bats, whales and dolphins emit high frequency echolocation calls to hunt their prey and evade danger, while some moth species have evolved the ability to emit anti-bat ultrasounds, to interfere with bats’ echolocation. Monkeys and gorillas are known to warn their communities of different dangers with distinctive calls.
Recognising the role of sound in the animal world, we should be alert to the disturbing noises generated by human activities that are threatening the daily lives and even survival of many animals. There are already cases reported of city birds altering their ways, as well as dolphin behaviour changing due to marine engineering works.
Studies have found that urban birds raise the pitch of their songs and calls to overcome the rumbling environment. The higher pitch, however, travels a shorter distance through the air. And not all birds are able to raise their voices. As for dolphins, researchers have observed that some were forced to head for quieter area with less resources (e.g. less food) because their echolocation system - that helps them to detect obstacles and food - was severely affected by the noises from frequent vessel traffic and marine reclamation works.
In comparison, some small animals with less mobility and less developed acoustic systems are facing even direr consequences. They may fail to cope with the noise challenge.
The world’s first Quiet Trail
As more research is carried out on how noise impacts individual species and ecosystems, the public is more enlightened regarding nature soundscapes - the non-visual landscapes formed by natural sounds such as insects and birds, and wind and rain. Quiet Parks International has set standards for natural soundscapes to promote a quiet environment for all beings, including humans, through education and accreditation. In 2022, the institution recognised Taiwan’s Cuifeng Lake Circular Trail as the world’s first Quiet Trail.
Apart from having few visitors, the local Forestry Bureau has made efforts to advocate “soundscape conservation”. Visitors are encouraged to stay silent and avoid using loudspeakers, and the natural sound-absorbing mosses are well-preserved.
Human-caused noises modify the natural environment
In Hong Kong, the close proximity of the city to nature has always been our pride. Unfortunately, we are seeing all kinds of works around or even within the countryside. The issue of noise pollution in the wild merits our attention. The government and academics should earmark more resources to study the impacts of urban noise on wildlife and rural ecology, focusing on species that are more sensitive to noise. Besides, noise mitigation measures to protect animals should also be adopted in land works, taking reference to the protocol of marine works.
In recent years, the countryside has become a hotspot for many Hong Kong people to take a breath of fresh air during the pandemic. The increased numbers of visitors result in increased noises from people talking and music playing from loudspeakers. Although these noises are less persistent than those from engineering works, they are more prevalent as people move around. More areas are likely to be affected by noise pollution. It is indeed time to carry out “quiet education” in Hong Kong!