Text/Hookefi
Recently, residents of Shanghai, Wuhan and Nanjing have revealed to the media that they have seen a kind of animal that "dogs are not dogs, cats are not cats" in their own communities or park green spaces, and there are many of them.
According to expert identification, this wild animal that ordinary people can't name is called "raccoon", which is the prototype of the idiom "a hill of raccoon".
They live in the city with their families in peace and quiet, and they are still national second-level protected animals on the Internet.
After years of environmental education and popularization, when people face wild animals, they no longer ask the question of "how can it be good", but turn to "will it attack humans?" "Will it carry the virus" and "Can it be brought home and raised?" ”
Over the years, from squirrels to weasels, from wild boars to raccoons, they have appeared frequently in cities, and city managers have to face a problem that needs to be considered and decided:
How do wildlife and cities coexist?
Photo/Courtesy of respondents
It's not an "interloper" but an "aboriginal"
In the face of the large number of "raccoons" in the city, the vast majority of citizens are still struggling with what this animal is, researchers have been paying attention to these urban animals for more than 10 years.
"The first time the raccoon appeared in the newspaper was around 2005, when the media consulted experts on it as a strange species." Wang Fang, research institute and doctoral supervisor of the School of Life Sciences of Fudan University in Shanghai, recalled to China News Weekly.
Raccoons are a very old canid. Its distribution was once very extensive, with 3 subspecies distributed in China, from the large and small Xing'an Mountains to Beijing, from Shaanxi Taihang to the Yangtze River Delta, and then southeast to Fujian Guangdong, southwest to Guizhou, Yunnan, and nearly half of China is the natural distribution area of raccoons.
Because of habitat loss, the impact of human activities and the action of other species, the wild population of raccoons is in a declining situation. Wang Fang said that because the entire behavior of raccoons in terms of feeding habits and habitat selection is very flexible and has a high degree of adaptability, they have found habitat space in the city.
In Shanghai, Nanjing, Wuhan and other places, raccoons have found easier and more accessible sources of food by eating domestic garbage discarded by humans. Their hiding environment has also changed from caves and tree roots to cracks under the balconies of residential villas, gaps in walls, storage rooms, cracks in bridge piers, gas pipes, abandoned sewers, etc.
Why do wildlife choose better habitats in cities rather than in the wild? In fact, the urban environment recovers faster than the wilderness and the urban-rural interface.
According to the data, by the end of 2020, the green coverage rate of Shanghai's built-up areas will be as high as 40%, not only with large areas of forests and wetlands, but also small and beautiful ecological areas such as street gardens and pocket parks.
At this time, the city will be like a hot spot, attracting the surrounding animals. Animals such as raccoons are good at adapting to the characteristics of the city, and there are basically no natural enemies in the city, as long as they can adapt, they are almost no threat.
"This class of species is ecologically known as a generalized species, and similar to raccoons are squirrels, weasels, and even ocelots." Wang Fang said.
In this way, raccoons quickly made their home in the city, and people gradually discovered them. Studies have shown that when there are less than 2 raccoons per hectare, people will hardly feel the presence of raccoons, but when this number exceeds 5, it will affect people's lives.
According to the statistics of Wang Fang's scientific research team, in 2020, Shanghai 12315 had about a thousand complaints about wildlife disturbances, some of whom were plagued by the excrement and noise of the raccoons, and some of whom were frightened by the raccoons.
Amazing adaptability
"To be honest, I didn't expect the raccoon to be so adaptable." Wang Fang said.
A few years ago, the research team of Fudan University tried to track wild raccoons in Shanghai, infrared trigger cameras, GPS tracking positioning collars, infrared thermal imaging survey instruments... More and more devices and methods have helped researchers gradually piece together the survival of raccoons in cities.
After three years of visiting, monitoring and researching, Wang Fang and his team found that at least more than 150 Communities in Shanghai currently have a distribution of Raccoons, and the number of potential raccoon communities is several times higher.
Distribution map of Shanghai raccoon. Photo/ Shanshui Nature Conservation Center
"Roughly calculated, in Shanghai alone, the number of raccoons is likely to be more than 5,000."
Over the past decade, the species seems to have acquired some peculiar ability to adapt to urban life, increasing rapidly in various areas such as Songjiang, Minhang, Pudong, Yangpu, Qingpu, and Fengxian. Such changes are still happening rapidly, not only leaving Shanghai and spreading to the nearby Yangtze River Delta regions such as Suzhou, Wuxi, and Nanjing, but also appearing in distant Wuhan.
One of the reasons for the rapid growth of the raccoon's population is its own feeding habits. From a taxonomic point of view, raccoons are located near the bottom of the canine system of occurrence trees, representing a unique evolutionary direction of canines.
Wang Fang said, "The raccoon's split teeth and canine teeth are not large, and the molars are relatively flat, which exposes its core direction in the evolutionary process - the line of competition with tigers, leopards, jackals and wolves for ferocious carnivores is too fierce, and even small and medium-sized carnivores foxes and ocelots are not easy to get along with." Then in the process of natural evolution, it is better to be more flexible, eat everything, and half and half protein and starch are more secure. ”
Flexible food and other lifestyle habits help raccoons gain an edge in the city.
"Before the winter season, we found that raccoons would uproot and chew grass; there were some hilly shrubs next to the raccoon habitat in Jinshan District, where they dug earthworms and hunted rats; in the urban environment of Pudong and Minhang, they mastered the design of communities and roads, ate garbage, picked up cat food, and multiplied in the cracks of the human world; and next to the pond in Songjiang District at night, we saw crucian carp and koi carp easily caught more than once."
In addition, the mating period of raccoons is in February and March of each year, the pregnancy period is about two months, and a litter can produce 6-8 cubs, and it can be deduced from this data that the reason for the recent large number of raccoons is that they are in the breeding season.
Originally, the survival rate of raccoon pups was low in cities, and stray cats and dogs, high-speed cars, and humans could kill them, but in recent years, researchers have found that the vast majority of raccoon pups have survived.
"If a community has a pair of raccoons in the spring, then in the middle of summer, the community can welcome 10 babies, and the speed and ability of this breeding is very fast."
What is more interesting is that in the wild survival of this animal, most of them lie out at night, choose to rest during the day, and forage at night, while in the city, they have changed.
In safe neighborhoods, they can hide properly. The raccoon has gradually become an animal that will come out during the day and come out at night, and will come out to bask in the sun at three or four o'clock in the afternoon, and in the winter, it will be a lot of activities during the sunny day.
In Shanghai, for example, the range of raccoons has also changed rapidly, spreading in four directions from a smaller area in the southwest of Shanghai, especially to the east and north of the city, and several obvious diffusion channels can be seen, and the diffusion rate is faster than expected.
What's more interesting is that solitary animals such as raccoons are even changing to social creatures for social activities, helping each other, gathering sports and hunting collectively, and not refusing to come to a large number of plant starchy foods. Not only that, the garbage discarded by humans, the lights and noises created by the raccoons have a very distinct adaptability.
They are rapidly making a difference in urban life.
Finding a way to coexist is the only option
Over the past few decades, researchers have lacked a data basis for urban animals, from squirrels to raccoons, to other wildlife, so researchers cannot assess the historical changes in these animals, and it is difficult to know how much the number of these animals has increased compared to before, and how much the degree and rate of change has been.
This is also the reason why Wang Fang chose to follow up and study raccoons for a long time. With such data assessments, we can assess how much they have changed over the next 5 to 10 years, and these data are the basis for decision-making.
What should city managers do in the face of the abundance of raccoons and other wildlife that appear in cities?
Media reports show that in July 2020, dozens of raccoons in a small area of Shanghai had a group sexual disorder, causing great disturbance. To this end, Shanghai issued the first wildlife hunting license, which safely transferred the raccoons in the community to the wild environment.
But in fact, capture transfer or even hunting is not necessarily a good idea.
In ecology, there is a technical term called ecological niche. Niche refers to the position occupied by a population in the ecosystem, in time and space, and its functional relationship and role with related populations.
Simply put, if there is a resource suitable for a certain animal, it will inevitably be used. If the ecological niche does not change, then simple capture and hunting will not play any role.
For example, rats and cockroaches can never be eliminated in the city, there will be crabs on the beach, there will be water birds in the mudflats, indeed, we can catch wild animals and send them away, but they will soon be occupied by new individuals, and the space that is captured will quickly replenish the original number, and there will also be a group of animals actively entering the city from the wild.
In the past, some cities would choose biological control to deal with harmful invasive organisms, will use the introduction of its natural enemies for control, with ecological laws to solve ecological problems, but for urban organisms are not applicable, they are neither harmful organisms, nor invasive alien species, and even they are native to this land.
The conflict and coexistence of humans and wild animals may be an eternal problem in the management of Wuhan, Shanghai, Beijing and even different cities, and an inevitable process in the process of urban ecological restoration.
Because biodiversity is the essence of the world we live in, it is both beautiful and conflicting.
For the coexistence relationship, Wang Fang believes that the best way to solve the problem of wild animals "entering the city" is to do a good job in the protection and restoration of the living environment of wild animals, retain the urban buffer zone, and minimize the direct conflict between wild animals and urban residents.
"Cities are first and foremost places where people live and work, and there is never an optimal solution for urban wildlife management, and conflict will always exist." No matter how good the system is, it needs to be continuously adjusted. ”
As for the question of whether the raccoon will hurt people and whether it can be raised, Wang Fang also gave the answer with data, "In the past ten years, there have been a total of three known raccoon attacks, all of which are passive injuries, two of which are conflicts with pet dogs. "At present, the probability of raccoons attacking people is very low, and it seems to be related to domestic dogs, and raccoons do not have active aggression towards people.
At the same time, raccoons are national second-level protected animals, which means that people can neither catch nor raise them, and certainly do not feed them.
Unlike the tigers that enter the village, the elephants that move north, and the leopards that flee, the raccoon is neither a "reckless person" who has lost his way, nor a "rebel" who yearns for freedom, but a "settler" who has made up his mind to settle down.
They are not the first settlers to enter the city, and they will never be the last.