It only took a few weeks of Coronavirus lockdown for animals to crawl out of their dens and finally start imposing their presence in the streets, gardens and squares of the large Italian cities that are now unusually quiet after people have been locked inside their homes to better deal with the health emergency. While half the planet has now become sort of suspended, and even the Olympics as well as thousands of events all over the world have been cancelled or postponed, nature doesn't stop. On the contrary, outside our windows is blooming one of the most beautiful springs ever - clean air, clear skies, birds singing their most beautiful songs.

In Milan, swans are swimming in the Navigli and a group of little cottontail rabbits are hopping in a small neighbourhood garden between the railway and the ring road. In Venice, the water in the canals is finally crystal clear and full of fish, and the ducks take long naps on the vaporetto stops. At sunset, dolphins swim in the port of Cagliari while wild boars run along the streets of Sassari. And yet, we're having conflicting feelings and thoughts about that: knowing that nature is taking back the cities is wonderful, breathing clean air amazes us. But, at the same time, we are feeling guilty, it's clear that we have gone too far in exploiting the planet and its resources. What lesson can we learn from all this? We asked three experts: Peter Del Tredici, American botanist and professor at GSD Harvard; Menno Schilthuizen, evolutionary biologist and researcher in Leiden; and Giovanni Bellotti, Italian architect, professor and researcher in Rotterdam (also, the drawings in this article were made by him).

Botanist, active at Harvard and the Arnold Arboretum in Boston since 1972, Peter Del Tredici is convinced of nature’s great capacity to fill every void. “Nature abhors a vacuum: weeds that grow in the untended land; birds, are always quick to colonize all sorts of leftover human-created habitats from building ledges to rubbles dumps in lakes to old mining pits filled with rainwater”, explains. “What we are seeing in the wildlife today is nature behaving opportunistically to exploit resources that are not being utilized by people right now. Opportunistic behavior is a universal characteristic of weeds which, combined with adaptability, make them well suited to deal with the rapid changes (mainly climate) that are currently transforming the world,” continues. Coming to the spread of the Covid-19 virus, Del Tredici explains that he sees it as the perfect manifestation of the globalization of the world we live in, of the breaking down of physical barriers that kept populations of organisms apart, and that now they no longer do so. “The Covid-19 virus got out of Wuhan and into the rest of the world by travelling with people on jet planes. The spread of the virus is nature’s way of exploiting the opportunity presented by globalization and urbanization of our planet”, American biologist adds. “The fact that humans have converted most of the planet into a factory designed to feed, house, cloth and transport themselves has converted a large percentage of the planet's net primary productivity into goods designed to promote human welfare. This transformation of nature into products for human consumption has set the table for the Covid-19 virus and a host of other pathogens that have the capacity to exploit the planetary resources that are stored up in our bodies. The fact that Covid-19 (and other viruses) jumped from a wild animal into the human population provides a powerful metaphor for nature reasserting itself in the face of the human exploitation of nature.”

Dutch evolutionary biologist, author of the book Darwin comes to town, explains that nature seems ready to build a new urban ecosystem. “It is indeed surprising how quickly animals and plants respond to this rather subtle change in our behaviour,” continues. “To me this shows the adaptability of nature, but above all, the impact we constantly have on the living spaces of other species. With just a few weeks of relative inactivity, animals are already changing their behaviour to fill the gaps that our lack of activity causes. Of course, these short-term responses are not evolutionary changes; they are opportunistic shifts in an already flexible behaviour.” The biologist explains that ecology is all about competition for space, food, and other resources. “As soon as our competitive power lessens, other species are moving in. This is why we see wild species moving into the city that previously were excluded”. “At the same time however,” he adds “we have to realise that a lot of urban species depend on our economic activities for food and other opportunities. Here in my hometown of Leiden, herring gulls, lesser black-backed gulls, jackdaws, and coots in the canals heavily depend on discarded food from the twice-weekly open market in the town centre. Now that that market does not take place anymore, these resident urban birds are in trouble. Some may be sufficiently inventive to find other ways of finding food, or become more aggressive in their hunt for human food. Others may starve. These quick, temporary changes in the ecology of the city show us clearly how strongly intertwined our lives have become with those of wild, human-adapted animals.”

“This forced lockdown is an opportunity to think about the relation between animals and humans, an opportunity to reach a new level of proximity,” adds Giovanni Bellotti, an Italian architect based in Rotterdam, where he also founded his Studio Ossidiana with Alessandra Covini. In his research The Wild City (2011, Why Factory), Bellotti (with Eric Revellé) hypothesized what would happen to a city if it were “uncontrolled, unplanned and subjected to any human activity” for 5, 10, 50 and 100 years. The city in his studio becomes the place where design, botany and architecture meet in a bucolic and wild setting. “The Coronavirus pandemic showed us a different kind of wilderness,” he explains. “On the contrary, it makes us aware that there are no boundaries anymore: humans are everywhere, there is no longer an exterior, we all live in a large planetary interior, with no space to isolate ourselves. More and more often we do coexistence exercises with nature. Changing the current situation, even a little, leads to rediscovering the fauna and flora that change in the blink of an eye. This strange new normality should be cherished, in order to rediscover other types of beauty and behaviours. There is the scary part, but also the beauty of discovery.”