Un puma walking the streets of Santiago de Chile. In April 2020, the images had gone around the world. In reality, it was the sixth time in less than a month that a big cat walked the pavement of the capital, made deserted by the strict confinement put in place in the city to fight against the Covid-19. The following year, an American team published In Current Biology a study analyzing the movements of six cougars – the North American name for the feline – during the periods of confinement imposed in the bay of San Francisco: it found that the beasts had indeed moved closer to urban areas.
Since then, various studies, with sometimes divergent conclusions, have scrutinized the behavior of deer, wild boars, badgers and even crows during what is now customary to call the anthropause. But the article published Friday, June 9 in the magazine Science appears from another staff. Signed by 175 scientists from 164 institutions around the world, it sifts through the behavioral changes of 43 species of land mammals when we give them free rein. Lions, giraffes, elephants, antelopes, gazelles, or even brown bears, reindeer, giant anteaters or ibexes: 2,300 individuals were closely monitored. And the result is striking: where humans have seen their mobility reduced, animals have increased theirs.
A complex question
The result may seem trivial. It actually answers a complex question that has plagued ecologist Marlee Tucker of Radboud University in Nijmegen, the Netherlands, for five years. In 2018, she established that the movements of animals were reduced where the human footprint was the most significant. “But we were unable to separate the effects caused by landscape changes, such as agricultural expansion, and human mobility itself”she explains. Were the animals fleeing the tarmac and cultivated land or the cars, tractors and their drivers?
The lockdown offered an unexpected opportunity to disentangle the two factors. The mammals studied had all been fitted, in previous years, with collars fitted with GPS sensors – a practice that has become commonplace for analyzing the behavior of wild species. By recording animal movements in this silent spring of 2020 and comparing them to observations made the previous year on the same animals and the same terrain, they were able to isolate the only effects of human mobility.
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