Lockdown did not lead to such a proliferation of wildlife in cities

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Throughout the strict lockdown that began a year ago, images of animals in urban environments or habitually frequented by people proliferated on social networks. "Nature recovers", was proclaimed in many of these posts. It is true that, coinciding with spring, there was an increase in the proliferation of weeds in parks and gardens, tree wells, road verges, and roundabouts. But did those images of groups of deer strolling with the philosophical air that all ruminants have in the squares and streets of cities around the world really indicate an explosion of wildlife caused by the decrease of human presence?

A study carried out by researchers at the Institut Català d'Ornitologia (ICO) and the Centre de Recerca Ecològica i Aplicacions Forestals (Creaf) has answered this question in the field of birds. And the data indicate that it is not the case. Birds did not invade cities, but simply became more visible. "We have seen that during lockdown there were the same number of birds in the cities, but they were easier to detect", says Òscar Gordo, a biologist at ICO and first author of the study. The results of the study, which was made possible thanks to the observations of 139 volunteers who spent 1,248 hours during the first month of lockdown, have been published in the journal Proceedings of the Royal Society.

On March 15, 2020, the day after the state of alarm was decreed, the project #JoEmQuedoACasa ("I stay home") was launched, which encouraged everyone to look at the birds and record observations on the platform Ornitho.cat, with the aim of measuring the effects of lockdown on birds. More specifically, it was proposed to study the 16 most common species in cities, among which are the blackbird, the sparrow or the heron. One month and nearly 20,800 observations later, the data collected were compared with those of the same period of the previous five years. The analysis revealed that, although there was no indication of an increase in observations, there was a noticeable change in the behaviour patterns of the birds.

Return to the natural rhythm

Under natural conditions, birds are very active at first light and early in the day. In urban environments, and especially in big cities, this time of day coincides with many people on the street. It is also one of the times of the day with more noise from traffic. All this morning noise means that, in general, urban birds are not so active at this time of day. During lockdown, however, as a result of the reduced activity and noise in the early morning, the birds regained a pattern of activity that is more natural to them and were more active at these times of the day.

"Once again, urban birds prove to be extremely plastic and adaptable to sudden changes, a characteristic that science had already attributed to them", explained Sergi Herrando, researcher at ICO and Creaf, and also author of the article, in a statement. "In birds like the yellow-legged gull or the heron, who are very intelligent and adaptable animals, the drastic reduction of traffic and the presence of people in the street encouraged them to use much more the early hours of the morning to look for food and even go deeper into the central nuclei of towns and cities", said Gabriel Gargallo, director of the ICO, in the same note.

The recovery of nature

The study adds to a line of research on the impact of human activity on nature and its recovery. In recent years, many people have used Chernobyl as an example of a place where, when human activity stopped, nature revives. The networks are abuzz with images of deer, foxes and wolves wandering through a ghost town where human constructions have been swallowed up by creepers. A similar thing is happening in Fukushima. Snapshots of wild boars and monkeys roaming under the walls of abandoned buildings have been used to vindicate the resilience of the natural world to the onslaught of human activity. "Man is more harmful than radiation", it has been proclaimed.

Scientific data, however, often show a certain stubbornness in dismantling the house of cards built on social media. Studies by biologist Timothy Mousseau of the University of South Carolina indicate that there are fewer birds in Chernobyl than in non-irradiated areas and that these birds have a higher incidence of tumors and deformities. Despite those images that have gone around the world, both in Chernobyl and Fukushima it has been proven that there are fewer mammals than in the areas free of radiation. The human impact on nature, then, goes far beyond four viral images.