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How are animals in cities related to each other while there are no human beings? Thanks to tens of thousands of photos taken by 150 cameras installed in private gardens in Berlin, A team of scientists has analyzed the ecological relationships between specimens of four species: two native wild ones, the fox (Vulpes vulpes) and the marten (Tuesday foina); an invader, the raccoonProcyon lotor); and another, domestic, the cat (Felis silvestris catus). And all this in combination with the disturbance modulated by quarantine and confinement caused by COVID-19. Attention spoiler: cats rule.
Avoid or confront, eat or be eaten, compete, take advantage or cooperate & mldr; Wild animal communities are structured around the interactions that occur when they share living space. urban environments represent a special case, since human presence and influence often change the rules of the ecological game substantially.
How are wild carnivores related in a city? Has the quarantine affected your behavior? To answer these questions, a team of scientists from the Leibniz Institute for Zoological and Wildlife Research (Leibniz-IZW) installed around 150 cameras in private gardens of different houses in Berlin, with the collaboration and permission of their neighbors, who thus participated in a citizen science project. The objective, to analyze the behavior of foxes, raccoons, marten and cats.
Private gardens, meeting places
The research is part of the citizen project ‘Wildlife researchers’, led by Stephanie Kramer-Schadt, a scientist at Leibniz-IZW (Germany), and lasted from autumn 2018 to the same season in 2020. The results have just been published. be featured in the ‘Journal of Animal Ecology’.
Raccoon | FJ Garcia
Scientists chose city gardens as a field of study for their ability to attract and scare away wild animals, by acting doubly as a potential source of food and a meeting place, both with humans and domestic animals.
The researchers combined the photos recorded by the cameras with the information available on the size of the gardens, the amount of vegetation, the potential sources of food, the height of the fences and the population density.
In each sample collection period (five different, each lasting a month), the cameras captured around 2,200 and 3,000 cats, 300 to 1,200 red foxes, 200 to 1,000 raccoons, and 50 to 300 martens. They also captured several photos of other mammals not relevant to the study.
“We were interested in how highly flexible and adaptable carnivore species interact space-time in human-dominated environments,” explains Julie Louvrier, from the Technical University of Berlin (Germany) and first author of the study. “We wanted to know if they use the same places and, if so, if they are avoided between species by going at different times of the day or night., for example & rdquor ;, continues.
More animal activity in fall
The research group found that the seasons of the year and the quarantine caused by the coronavirus pandemic influence “quite a lot & rdquor; in the frequency with which the species were recordedThey also found that fall is a season of much more activity for foxes, raccoons, marten and cats, unlike spring.
During the mobility restrictions, Berliners used their gardens more than usual during the day, forcing the fauna to be more nocturnal. the presence of foxes, marten and raccoons in the gardens increased during periods of confinement, “Probably due to the lower human presence in the urban space & rdquor ;, the analysts point out.
Red fox | Pixabay
And it is that, although these species of wild carnivores are accustomed to a certain extent to the presence of humans, avoid encounters with people, concentrating his movements during the night, the period of less activity in the city.
Whenever a greater number of foxes were observed, the same happened with raccoons and martens. And vice versa, since the three species use the same resources of the urban environment. But these species try to avoid each other: there is a delay between the consecutive detections of the different species in the same spaces.
The cat, the dominant species
A higher presence of cats meant more detections of raccoons, as they use the presence of raccoons as a potential indicator of leftover cat food. Martens and foxes, on the other hand, did not appear more frequently when there were cats, which, according to the scientists, indicates “a hierarchy of the four species, among which the cat is the dominant& rdquor ;.
This claim was corroborated by another surprising conclusion from the study: cats do not avoid other animals, whatever the time of day, although their body mass – considered an indicator of dominance in the wild – is normally less than that of foxes and raccoons.
Cat | Pixabay
“Humans modify the behavior and way of life of wild species. The quarantine was a blessing, as it provided an opportunity to study what our wild neighbors do. when people suddenly disappear from urban space & rdquor ;, emphasizes Kramer-Schadt. It was important because human pressure causes an “exacerbated effect & rdquor; on community dynamics.
“Our research sheds some light on the rules governing interactions in a medium-sized carnivore community living in an urban setting,” concludes Louvrier. Something has become clear: domestic animals exercise their dominance over local fauna, even on species that are relatively well adapted urban environment.
Baseline Study: https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.13635
Website of the citizen science project ‘Wildlife researchers’ (in German): https://berlin.stadtwildtiere.de/