Beijing Swift, Gu Jianli made a home
Expert: Ancient buildings are not the only places to build nests, swifts are adapting to cities and begin to breed in tall buildings and other places
On July 11, Beihai Park, Swift flew over the Wulong Pavilion.
Photo by Beijing News reporter Xue Jun
The 36-year-old Bai Tao used to go to Beihai Park and Zhongshan Park as a child.
Every summer, the sight of flocks of Beijing swifts flying around the magnificent ancient building is a lingering memory for him.
As a summer migratory bird, Beijing swifts fly to Beijing from far away southern Africa in early April every year, and build nests in ancient buildings such as the Summer Palace, Lama Temple, Zhengyangmen and other places.
Their small and flexible figures are in harmony with the exquisite ancient buildings, and the Beijing Swift has also become an ecological symbol of the ancient capital Beijing.
Ancient building structures are easy to form "artificial caves"
At the Wulong Pavilion in Beihai Park, Beijing Swift spreads its sickle-shaped wings and dives. It slows down when it reaches Bai Tao, and swept past him almost to the nest under the red beam.
According to Bai Tao, a volunteer of the Beijing Swift Survey Project, the moment of close contact with Swift is very wonderful.
"Their nest in Wulongting is right above my head, and I can clearly see the details of the Beijing Swifts entering the nest."
The Kuoruting in the Summer Palace is also a favorite habitat for Beijing swifts during the breeding season.
Due to the high density of swift nests, since 1997, researchers have carried out ringing and recycling experiments for swifts here.
Around Zhengyangmen, Tianning Temple Pagoda, Lama Temple and other ancient buildings, you can often see swifts circling.
Why does Beijing Swift prefer ancient buildings?
Zhao Xinru, an ornithologist at Beijing Normal University, speculates that there are historical reasons for this.
The evolution of Beijing Swift's reproductive ecology tends to be close to the living environment of human beings.
Beijing has royal buildings such as the Temple of Heaven and the Summer Palace. The beams, purlins and rafters of these buildings criss-cross, forming "artificial caves", which provide an ideal breeding place for swifts.
"Palaces, temples, archways, and ancient pagodas often form wooden caves at the top of these ancient buildings. Wooden structures have better thermal insulation, so they are more favored by Swifts."
Zhuo Xiaoli, a biology teacher at Beijing No. 4 Middle School, said that swifts with long wings and small bodies "prefer" to build their nests in the gaps between the rafters and purlins of ancient buildings with a bucket arch structure.
In this way, after their wings are closed, they can hide in a small and hidden space, which is conducive to hatching and brooding, and prevents predators from predation.
Shi Yang, a senior engineer at the Beijing Wildlife Rescue Center, said that before the founding of New China, because Beijing lacked high-rise buildings, Swift mainly chose royal buildings and ancient temples and pagodas to build their nests, which also matched the image of Beijing's ancient capital.
Swifts have four toes forward and are suitable for breeding in caves
The Beijing Swift's tarsus is so short that it looks like it has no feet.
According to reports, their toe structure is four-toed forward, known as the fore-toed type, so they are not suitable for walking upright on flat ground, and they cannot hold wires or branches.
This toe-shaped structure makes them more suitable for hanging and clinging to the crevices of cliffs, ancient buildings and walls.
Therefore, the swift was also called the "footless bird".
Except that they need to enter the cave for spawning, hatching and brooding during the breeding period, they basically eat, drink, mate and sleep all year round in the air.
However, in Zhao Xinru's view, the foot structure of Beijing swifts and their preference to inhabit ancient buildings is not a simple "causal" relationship, but a synergistic developmental relationship between the evolution of the swift's hindlimb morphological structure and the evolution of its hindlimb function.
"The evolution of each species, its body structure and functional evolution are closely linked."
He said that, unlike the "three fronts and one back" toe structure of other birds, the four-toed forward of the swift evolved over a long period of time. It tends to breed in burrows, needs successful climbing, flies day and night, and seldom touches down. Structure formed by habit.
At the same time, such a structure is more conducive for them to find suitable burrows to nest and reproduce.
Gradually adapt to urbanization and breed in bridge holes or tall buildings
Swifts accompany ancient buildings and have become a unique cultural business card in Beijing.
According to Li Kun, deputy chief of the Publicity Section of the Summer Palace, the pavilion of the Summer Palace is wide and tall, and the gaps between the rafters at the top are densely populated adjacent areas of Beijing swifts.
Researchers have been doing ring records here for more than 20 years, and statistics have found that more than 30% of Beijing swifts return here every year to build nests and breed.
"The Summer Palace is the connecting corridor between the city and the suburbs. The mountain-shaped water system here provides abundant food for Beijing swifts." She said that the Summer Palace will protect the ecology and provide a suitable living home for Beijing swifts.
At the same time, in order to create a quiet living space for swifts, from 2019 onwards, the Summer Palace’s Kuoru Pavilion will be under closed management, and four entry and exit passages will be fenced, and tourists can visit outside the railings.
In recent years, bird experts have discovered that ancient buildings are not the only nesting places for Beijing Swifts.
With the development of the city, swifts are also slowly adapting to the city and begin to breed in modern tall buildings or overpasses, such as the holes or gaps of overpasses such as Tianning Temple Bridge and Jianguomen Bridge.
Zhao Xinru said frankly that some cultural relics protection units installed anti-bird nets on ancient buildings to prevent bird droppings from damaging the ancient buildings.
It is thought that this prevents swifts from making their nests.
"It makes sense in theory, but how big is the impact? It remains to be studied with numbers."
He believes that a balance should be found between the protection of ancient buildings and the protection of swifts.
"Some ancient buildings are themselves cultural relics and intangible cultural heritage. The protection of these cultural relics is to protect human civilization and be responsible to society. Because society and human beings are also part of nature."
He said that Beijing Swifts will not always look for ancient nests, they are actively adapting to the development of human society and the changes of human buildings.
"Their breeding habit is to look for caves. As for whether the cave is a natural cave or a cave of a building, a cave of an ancient building or a cave of a modern building, Swift can make a choice according to local conditions."
Over the years, Zhao Xinru was delighted to discover that some dormitories and office buildings of Beijing Normal University welcomed swifts to build their nests.
"Some of the roofs and eaves of old buildings fell off, forming caves. Swifts came in and out, and burrowed here to breed."
The Beijing Swift survey conducted by the Beijing Wildlife Rescue Center shows that Swifts are gradually shifting from ancient buildings to modern buildings, and Swifts are gradually adapting to urbanization.
"Beijing has more and more tall buildings, swift nests have shifted to modern buildings, and the nest area has been scattered from the previous relatively concentrated points." Shi Yang said.
To attract swifts, artificial nest box with tweet recording
In order to give Beijing swifts more places to settle in Beijing, people try to set up artificial nests for them.
On the eve of the 2008 Beijing Olympic Games, a "Swift Tower" was built in the North Park of the Olympic Forest Park.
The tower was advocated by environmentalists and designed by Tsinghua University. The tower is 20 meters high and has 2,240 bird nest boxes.
However, so far, the effect is not ideal.
The tower did not welcome the reproduction of Beijing swifts, but attracted some sparrows.
Zhao Xinru said that the design of the "Swift Tower" may not be suitable for Swift, and further experiments and improvements are needed in the future.
However, the pace of protecting Beijing Swift will not stop.
"At present, the China Bird Watching Society (full name: Bird Watching Professional Committee of China Biodiversity Conservation and Green Development Foundation) and the China Garden Museum have hung the artificial nest box of Beijing Swift." Zhao Xinru introduced that the nest box refers to the German Institute Swift nest box scheme made.
In terms of size, the Beijing Swift is larger than the common Swift named subspecies distributed in Europe, so the size of the nest box is also increased accordingly.
The artificial nest box is not a nest for Beijing swifts, but a burrow for them.
The "Beijing Garden Expo Park" area in Fengtai District, where the Chinese Garden Museum is located, lacked ancient buildings in the past, making it more difficult to attract Beijing Swifts.
"To this end, the China Garden Museum insists on an experiment to attract Beijing swifts by playing high-fidelity swifts and cooperating with artificial nest boxes."
Zhao Xinru is very optimistic about this project, "It will definitely be successful, but it will take some time, maybe three years or even five years."
What is certain is that, in addition to the beautiful ancient buildings, Beijing Swift will meet citizens on more occasions in the future.
Beijing News reporter Zhang Lu