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Summer nights in Sheffield came very slowly, and it was past 9 p.m. when the sun reluctantly set. The sound of Hillsborough Stadium has subsided, the rock and roll of the West Street Beer House has come to an end, and the flow of traffic has become sporadic on the main road from the central city to the town. As the night grew darker, after a day of hustle and bustle, the great city surrounded by seven mountains was showing a rare tranquility, but when everything was quiet, the birdsong like a flute came from the branches- the Eurasian plover (Erithacus rubecula, another name we are more familiar with, the robin) began to chirp.
A common robin in Europe
The people of Sheffield are no strangers to robins. More than a hundred years ago, when the area was shrouded in the exhaust gas of the steel industry, the robins that walked through the garden branches and even often landed next to people and chirped became a symbol of sheffield pastoral dreams. Curiously, however, in many of the pastoral poems depicting the robin, the image of the orange feathers on its chest that playfully trembles when it chirps in the sun is rarely recorded. In fact, the robins that live far away from the urban woodlands today are still strictly diurnal birds, and it seems that only the robins living in large cities like Sheffield prefer to sing at night.
Is it the city's lights that attract robins to live a nightlife? Of course not. They are only small victims of urban prosperity.
<h2 class = "rich_media_title" > noise, natural background music</h2>
Like robins, chirping is an important way for many birds to convey information. Birds in the courtship season attract the opposite sex with their high-pitched chirps, gregarious birds use their sharp calls to alert their companions to the arrival of predators, and baby birds crouching in their nests will also tell their parents who are foraging nearby with their voices - "Baby is very hungry!" ”
However, birds are not the only singers in nature, the wind blows the leaves, the babbling of streams, the sound of apes on both sides of the river and the frogs chirping at night are common sound sources, in the particularly noisy summer, there are even deafening cicada ensembles and thunder that destroys decay, "communication basically depends on roaring" Birds want to use sound to transmit information, must consider the reasonable avoidance of these natural "noises".
Fortunately, birds already have many countermeasures. "Noise avoidance" is the most common strategy: birds generally have good maneuverability, and birds are more likely to fly to relatively secluded environments when noise sources with poor coverage appear, and when noise sources are very extensive but incoherent — such as intermittent thunder — birds also learn to "cross peaks" in between thunders.
The vast majority of birds avoid the interference of natural noise in this way from space or time, but there are always some birds that need to face very special situations. Piprites chloris and Thamnophilus schistaceus are two species of birds whose habitat coincides, their song frequency and amplitude are very close, and the calls of the two neighbors often overlap and interfere with each other, and what is more difficult is that the initiative of the two is significantly different in avoiding each other - the black-crowned antwren especially likes to interject, and sometimes the song of the spotted-winged eagle is not over, and the black-crowned antbird rudely "grabs the wheat". But as long as the black-capped antbird's song field is not over, the spotted-winged eagle will always remain silent. Apparently, the former has lost many opportunities for singing and communication, and the resulting decrease in courtship or vigilance efficiency may explain why the population density of the spot-winged petite wren living in these areas is always lower than that of its neighbors. In contrast, the noise that the black-faced grebe (Abroscopus schisticeps) needs to overcome is more surging and persistent—the bird prefers to move near rushing rivers, and the never-ending torrential sound completely disables ordinary song communication, so that the black-faced warbler has evolved the ability to use ultrasonic communication, which is the same strategy as many frogs living near the rapids.
Relatively humble spot-winged petite
Black-capped antwrens that like to grab wheat
The example of the black-faced warbler is enough to illustrate that no matter how severe and complex the noise disturbances in nature, birds can always adapt to them over a long evolutionary process and use different strategies to counteract the noise interference of the song as much as possible.
But when another, more complex, more turbulent type of noise emerges rapidly along with the rise of human cities, bird strategies are no longer available.
< h2 class="rich_media_title" > urban noise, a sudden appearance of an alternative note</h2>
We can assert that most of the noise we face in cities today came in the short hundred years after the Industrial Revolution – before that, when the buzz of people was the top description of noise levels, but now the whistles of cars and boats and the noise of factories have become the mainstream of urban noise. Especially after the end of World War II, the global prosperity has rapidly iterated on the urbanization process in Asia and Latin America, and many cities have bid farewell to the idyllic appearance in just a few decades, and their development can not only be reflected in the rise of GDP and built-up area, but also intuitively reflected in the number of decibels of urban noise that continue to break through new highs.
As highly adaptable biological representatives, in the process of human cities constantly replacing natural landscapes, many birds have not left, they adapt to the city life of nesting under the eaves, turning over kitchen waste foraging, but the sharp rise in noise changes really catch them off guard.
For example, Sheffield, where the robin lives, is a city that thrived on the steel industry, and although today it has bid farewell to its "silly big black and rough" appearance due to urban upgrading, noise pollution continues to deteriorate. Throughout the 1990s, Sheffield's noise energy levels doubled, peaking during the morning and evening rush hours, forcing robins to significantly delay their chirping until night in order to "stagger peaks". Similarly, the Turdus merula in Leipzig, Germany, uses early singing to avoid the morning peak, and their "morning exercise" can be 5 hours earlier than their counterparts living in natural forest areas.
Cities that are very different from their natural environment bring endless pressure to the survival of birds | www.express.co.uk
Robins are actually the lucky ones. Most of the noise in the city is low frequency and high energy, and its frequency is generally lower than 2kHz, rarely exceeding 5kHz, while the song frequency of most birds is distributed between 2 and 9 kHz. Urban noise mainly affects the low-frequency part of bird calls, but many birds are limited by their physiological structure and can only emit low-frequency calls, making it more difficult for them to communicate in cities. Since the end of the 19th century, the famous European painter Rembrandt's hometown of Leiden in the Netherlands has developed rapidly from a small textile and printing town to a major metallurgical and building materials town, industrialization and population increase have made the noise pollution here very serious, the average noise during the day and night reached 55 decibels, at the same time, the common birds in the city have become very single, and the giant has become an absolute dominant species, which is precisely because the chirping of the giant is generally high-frequency, and its lowest chirping frequency can also cover the influence of urban noise.
But even the big sometimes had to compromise: in 1947, Finland's capital, Helsinki, was a relatively secluded city where 70 percent of the big used 3-note chirping, and with Helsinki's rapid industrialization, the big changed dramatically — 65 percent abandoned the 3-note designation in favor of shorter, less noisy 2-notes.
A big in a park in the heart of Helsinki Street
In cities with relatively little noise pollution, areas close to highways, a source of pollution, remain off-limits for many bird activities. Years of surveillance have found that many birds can forage on the side of the road or look for nesting materials, but do not breed nearby, perhaps because the noise of traffic drowns out the chirping of chicks begging. The inability to obtain sufficient food in time has greatly reduced the survival rate and growth rate of chicks.
Urban noise has clearly altered the courtship behavior of birds, as shown in the picture of two pigeons in courtship on the streets of Tokyo
In addition, studies have found that noise can hinder the selection of the opposite sex during bird courtship — in nature, females prefer males with lower song frequencies, and low chirps usually mean that males are larger, better fit, and more experienced in breeding and feeding offspring. But the courtship of these "Diamond King Old Five" is perfectly covered by low-frequency noise in the city, and most of the candidates who can pass into the ears of female birds are issued by candidates with higher audio. As a result, male birds have a hard choice between showing charm and improving the success rate of sound transmission, and girls need to face the risk of not finding a suitable groom or mating with a poorly qualified opposite sex throughout the breeding season. Even if the pairing is successful, the noise interference will affect the communication between the mating parties throughout the feeding period, and then affect the stability of the male-female relationship - after all, after leaving the nest, there is neither a shadow nor a sound, how do I know if you ran away with the old king next door?
On the streets of Brooklyn, a hunting falcon with the pigeons it catches
If the impact of noise on mating events concerns the next generation, then its interference with the sound of vigilance calls and the recognition of predators is directly related to the birds' own lives. Fringilla coelebs, a common bird in European cities, have shown in many ways their adaptation to urban life – compared to their counterparts in rural areas or natural woodlands, the urban finches tolerate people getting closer together, or even landing directly near people to feed. The more readily available food source in the city is the temptation to attract them, but in addition to humans, there are still many threats in the city, domestic cats, squirrels and some crows are its potential natural enemies, with the intensification of noise interference, the city's population must spend more energy visual vigilance, because the detection of natural enemies time-consuming encroaches on the time spent on foraging time, the foraging efficiency of the birds is reduced, and the average weight is not as good as that of the same kind living in the natural woodland.
<h2 class="rich_media_title > noise is already everywhere</h2>
As the place with the most intensive and intense human activities, the impact of noise pollution on animals is also more concentrated and prominent, but outside the city, noise pollution has long been ubiquitous.
Two Canada goose forced to lay eggs on the side of the highway
As an extension of human activities in wilderness areas, dense transportation facilities have become a major source of noise pollution in the wild environment. Road, rail, plane and boat routes continue to pass through once off-the-beaten-track areas, and the noise also profoundly affects the pace of wildlife's lives. Wildlife scientists have studied rodents in the Shennongjia area and found that the closer to the road, the lower the distribution density of rodents, which is the same as the distribution trend of birds around roads in cities.
In addition, tourism activities are also one of the "culprits" that bring noise and disturb the habitat of wild creatures. The Wumuyu and Mule Pagoda in the Zhangjiajie scenic spot are close to the highway, and the main noise pollution comes from traffic, while the noise from Jin whip Creek, HuanglongDong and Grand Canyon, where the main passenger flow in the scenic spot is concentrated, comes almost exclusively from tourists. During the tourist season, the average noise here reaches 64.7 to 72 decibels, even exceeding the normal noise level of many cities. Excessive noise drives the local Chinese-striped hordes, which is the main food for the local salamander, and the noise itself affects the rhythm of the salamander's movement out of the hole.
In the middle of summer, yachts in the port of Opatija and bottlenose dolphins in the nearby sea
To make matters worse, the victims of the noise include not only birds and chocobots, but also marine animals. The Croatian coastal town of Opatija, famous for Princess Sissi's favour, has stunning coastal scenery and every summer this "back garden of Europe" is filled with private yachts. In addition to these auras, opatija has another identity off the coast – it is the traditional breeding ground for populations of bottlenose dolphins in the Adriatic Sea. In recent years, the noise from yachts has forced the dolphins to migrate seasonally and even show signs of abandoning the breeding grounds.
More than half a century ago, Rachel Carson painted a terrible picture of nature falling silent in Silent Spring, which also promoted widespread concern about pesticide abuse around the world, but unlike gas, solid, and liquid pollution, noise pollution cannot be intuitively perceived, so that we ourselves, who are also deeply affected by it, often ignore it. What is more embarrassing is that figurative pollution is easy to control, abstract noise pollution is more difficult to cure, and the story of Sheffield, which has eliminated backward production capacity, best reflects this dilemma. However, we cannot let it go, after all, the "noisy spring" may be heavier than the "silent spring".
Source: Fruit Shell Network
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