how do wild animals act when there are no humans?

Wild animal communities are shaped by varied interactions like eating or being eaten, taking advantage or cooperating. There are many types of interactions that different species can carry out when they share the same space. But what about urban environments?

It is a different framework, a special case, since the fact that the human being exists and influences in this environment may have substantially changed the rules of the game. Here starts the project of a team of researchers from the Leibniz Institute for Wildlife and Zoological Research (Leibniz-IZW).

With the Help from Berlin citizen scientists (Germany), the researchers installed around 150 outdoor cameras, in their gardens or parks, in five rounds from the fall of 2018 to the fall of 2020 in different houses in Berlin, where, with their collaboration and permission, they took tens of thousands of wildlife photographs, to analyze the behavior of the foxes (Vulpes vulpes), the mapaches (Procyon), los gatos (Pelus catus) y las martens (Tuesday foina), before and after the confinements around the world due to the covid-19 pandemic. The red fox and martens they are native species; the raccoon, an invasive species, and the cat, an domestic.

“Humans impose strong selective forces on wild species, thus modifying their behavior and way of life”

For each sampling season, they were chosen new citizen scientists and everytime about 200 volunteers participated. Let us remember that for urban wildlife, private gardens and allotments can represent a crucial source of food and shelter.

The city of berlin, object of the study, was divided into a grid of 300 cells of two kilometers on a side, city gardens being selected as the field of study for their simplicity in attracting and repelling wild animals, both with humans —or the absence of them— and with domestic animals such as dogs and cats. all these places staged the scenes of these wild species that move through urban environments.

How did the wildlife behave in the city?

This analysis is part of the citizen project ‘Wild life researchers’, led by Stephanie Kramer-Schadt, a scientist at Leibniz-IZW (Germany), and determined how foxes, raccoons, martens and cats they got along with people and each other in the city. Of course, the three wild species used the same locations but with little temporal overlap during the night. Both foxes and raccoons and stone martens they avoided domestic cats at all costs. They were the kings of the city.

Domestic cats became ‘the kings’ of cities during confinement. (EFE/Balaz Mohai)

Domestic cats are a special case: on the one hand, a greater presence of cats also represented a greater presence of raccoons (Raccoons probably use the presence of cats as a substitute for pet food.) But again, foxes and martens were not more likely to show up when cats were present, indicating a hierarchy of the four species, being in this case the cats the dominant species.

In the absence of human beings during the mandatory confinement due to the pandemic, the cameras recorded an increase in their presence; wild species were most frequently viewed, especially at night. And it is that the general presence of foxes, martens and raccoons in the gardens increased during the running of the bulls, probably due to a general decrease in the presence of people in the urban space.

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It is curious, because the cities represent a novel environment for wildlife species, since our activities disturb their presence during the day with traffic, highways and a lot of noise and movement. These modifications that we humans have made in our environment are new in terms of evolutionary times and species have to quickly adapt to them. Consequently, the communities that are formed in such a novel environment also adapt, as well as their interactions and niche segregation.

“Humans impose strong selective forces on wild species, thus modifying their behavior and way of life. Quarantine was a blessing, as it provided the opportunity to study what our wild neighbors do when people suddenly disappear from urban space”, explains Stephanie Kramer-Schadt. “Our research sheds some light on the rules that govern interactions in a community of carnivores medium-sized living in an urban environment”, concludes Julie Laborer, from the Technical University of Berlin and guest scientist at the Department of Ecological Dynamics Leibniz-IZW.

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