Shrinking natural habitats push wildlife and cities into contact
Cities like Detroit in the US take efforts to accommodate wildlife as climate change poses challenges for conservation.
In a bustling metro area of 4.3 million people, Yale University wildlife biologist Nyeema Harris ventures into isolated thickets to study the most elusive residents in the United States city of Detroit — coyotes, foxes, raccoons and skunks among them.
Harris and her colleagues have placed trail cameras in woodsy sections of 25 city parks for the past five years. They’ve recorded thousands of images of animals that emerge mostly at night to roam and forage, revealing a wild side many locals might not know exists.
“We’re getting more and more exposure to wildlife in urban environments,” Harris said while checking the devices, fastened to trees with steel cables. “As we’re changing their habitats, as we’re expanding the footprint of urbanization … we’ll increasingly come in contact with them.”
Animal and plant species are dying off at an alarming rate, with up to one million threatened with extinction, according to a 2019 United Nations report. Their plight is stirring calls for “rewilding” the places where they thrived until driven out by development, pollution and climate change.
Those threats are front and centre this week as the UN begins its COP15 Biodiversity Conference in Montreal, Canada on Wednesday, December 7. Scientists, advocates and delegates from more than 200 countries will meet to discuss the “unprecedented” decline to ecosystems around the world.
UN chief Antonio Guterres recently stated that humanity’s zeal for economic growth had become a “weapon of mass extinction”. In the face of that crisis, rewilding seeks out a more balanced existence with the natural world.
Rewilding generally means reviving natural systems in degraded locations — sometimes with a helping hand. That might mean removing dams, building tunnels to reconnect migration pathways severed by roads, or reintroducing predators such as wolves to help balance ecosystems.
The idea might seem best suited to remote areas where nature is freer to heal without interference. But rewilding also happens in some of the world’s biggest urban centres, as people find mutually beneficial ways to coexist with nature.
The US Forest Service estimates 2,428 hectares (6,000 acres) of open space are lost daily as cities and suburbs expand. More than two-thirds of the global population will live in urban areas by 2050, the UN says.
“Climate change is coming, and we are facing an equally important biodiversity crisis,” said Nathalie Pettorelli, senior scientist with the Zoological Society of London. “There’s no better place to engage people on these matters than in cities.”
In a September report, the society took note of rewilding in metropolises such as Singapore, where a 2.7-kilometre (1.7-mile) stretch of the Kallang River has been converted from a concrete-lined channel into a twisting waterway lined with plants, rocks and parkland.
The German cities of Hanover, Frankfurt and Dessau-Rosslau designated vacant lots, parks, lawns and urban waterways where nature could take its course. As native wildflowers have sprung up, they’ve attracted birds, butterflies and bees, even hedgehogs.
Chicago’s Shedd Aquarium and the non-profit Urban Rivers are installing “floating wetlands” on part of the Chicago River to provide fish breeding areas, bird and pollinator habitats, and root systems that cleanse polluted water.
Urban rewilding can’t return landscapes to pre-settlement times and doesn’t try, said Marie Law Adams, a Northeastern University associate professor of architecture.
Instead, the aim can be to encourage natural processes that serve people and wildlife by increasing tree cover to ease summer heat, store carbon and host more animals. Or installing surface channels called bioswales that filter rainwater runoff from parking lots instead of letting it contaminate creeks.
“We need to learn from the mistakes of the mid-20th century — paving over everything, engineering everything with gray infrastructure” such as dams and pipes, Adams said.
Detroit’s sprawling metro area illustrates how human actions can boost rewilding, intentionally or not.
Hundreds of thousands of houses and other structures were abandoned as the struggling city’s population fell more than 60 percent since peaking at 1.8 million in the 1950s. Many were razed, leaving vacant tracts that plants and animals have occupied. Non-profit groups have planted trees, community gardens and pollinator-friendly shrubs.
Conservation projects reintroduced ospreys and peregrine falcons. Bald eagles found their way back as bans on DDT and other pesticides helped expand their range nationwide. Anti-pollution laws and government-funded cleanups made nearby rivers more hospitable to sturgeon, whitefish, beavers and native plants, such as wild celery.
“Detroit is a stellar example of urban rewilding, ” said John Hartig, a lake scientist at the University of Windsor in nearby Ontario, Canada and the former head of the Detroit River International Wildlife Refuge. “It’s been more organic than strategic. We created the conditions, things got better environmentally, and the native species came back.”
To Harris — the Yale biologist, who was formerly with the University of Michigan — Detroit offers a unique backdrop for studying wildlife in urban settings.
Unlike most big cities, its human population is declining, even as its streets, buildings and other infrastructure remain largely intact. And there’s diverse habitat. The landscape ranges from large lakes and rivers to neighbourhoods — some occupied, others largely deserted — and parklands so quiet “you don’t even know you’re in the city”, Harris said while changing camera batteries and jotting notes in a woodsy section of O’Hair Park.
Her team’s photographic observations have yielded published studies on how mammals react to each other, and to people, in urban landscapes.
The project connects them with local residents, some intrigued by coyotes and raccoons in the neighbourhood, others fearful of diseases or harm to pets.
It’s an educational opportunity, Harris said — about proper trash disposal, resisting the temptation to feed wild animals and the value of healthy, diverse ecosystems.
“It used to be that you had to go to some remote location to get exposure to nature,” said Harris, a Philadelphia native who was excited as a child to glimpse an occasional squirrel or deer. “Now that’s not the case. Like it or not, rewilding will occur. The question is, how can we prepare communities and environments and societies to anticipate the presence of more and more wildlife?”