Tucker and 174 colleagues analysed global data from land mammals tracked by GPS devices. “There were many media reports that nature was recovering during those first lockdowns. For example, cougars were roaming the streets of Santiago, Chile, but we wanted to know: is there any evidence of this? Or were people simply paying more attention to everything while being at home?”, asks Tucker. Co-author Calabrese has been conducting research at the interface of ecology and data science at the HZDR institute CASUS since 2020. He explains: “There is very rarely an opportunity to track how animals adapt their movement patterns in response to a change in human behavior, achieved in the form of a natural experiment on a global scale, using so many mammal species.” This was a unique opportunity, he concludes, because the world virtually stood still during the first phase of the pandemic: “Thanks to the global network of scientists, it was possible to observe and evaluate the reactions of the animal kingdom.”
Movements of mammals
Tucker and colleagues collated data from the movements of 43 different species of land mammals from around the world. In total, more than 2,300 individuals were included: from elephants and giraffes to bears and deer. The researchers compared the mammals’ movements during the first period of lockdowns, from January to mid-May 2020, with movements during the same months a year earlier. “We saw that during strict lockdowns, animals travelled up to 73 percent longer distances in a period of 10 days than the year before, when there were no lockdowns. We also saw that animals occurred on average 36 percent closer to roads than the year before. This is probably because those roads were quieter during strict lockdowns,” outlines Tucker.
There are several explanations for these results: there were fewer people outside during strict lockdowns, giving animals the opportunity to explore new areas. “In contrast, in areas with less strict lockdowns, we saw that animals travelled shorter distances. This may have to do with the fact that during those lockdowns, people were actually encouraged to go into nature. As a result, some nature areas were busier than before COVID-19,” says Thomas Müller, Senckenberg Biodiversity and Climate Research Centre and Goethe University Frankfurt, who designed the study together with Tucker.
The lockdowns provided a unique opportunity to study the effects of an abrupt change in human presence on wildlife. “Our research has shown that animals can respond directly to changes in human behavior. This offers hope for the future, because in principle this means that making some adjustments to our own behavior could have a positive effect on animals,” Tucker concludes.