Like many of you, I’ve been working from home due to the Coronavirus pandemic. My University suspended face-to-face classes two weeks ago and closed the campus to all nonessential personnel on Sunday night. Knowing this was coming, I packed up my desktop, hard drives, and essential books, and brought them home with me and got ready to spend the next few weeks inside.
There have been reports of air pollution dropping and decreases in carbon dioxide across China. While the change to our normal routines is undoubtedly taxing on all of us, urban animals are also experiencing a disruption in their daily lives as places like Times Square in New York City empty. Around the world, as tourism decreases and residents stay indoors, animals that normally benefit from intentionally placed or accidentally dropped food are likely changing their daily habits and switching diets.
Robert Seamans, PhD from the NYU Stern School of Business proposed that fewer people in parks would lead to less trash, therefore fewer pigeons and rats.
As another example of #QuarantineSpillovers:
staying inside more–>
fewer people in parks–>
less trash in parks–>
fewer pigeons & rats(but what are the effects on their predators, like red-tailed hawks, @localecologist ?)
3/N
— Rob Seamans (@robseamans) March 22, 2020
Anthrodependent organisms like pigeons and rats are closely linked to humans and therefore changes in the human population may lead to changes in the pigeon and rat population. Budding ecologists are often taught about the classic cyclic relationship between lynx and hares; an increase in snowshoe hares (the prey) leads to an increase in lynx (the predator) which causes a decline in the snowshoe hares, which leads to less food for the lynx and a decline in the lynx population, which allows for an increase in the snowshoe hares (Figure 2).
But anthrodependent organisms are often generalists (which is part of why they survive so well in urban environments). So will these anthrodependent species follow the lynx-hare cycle? Or will they find alternative food, reverting back to more natural foods, as human refuse diminishes, but still maintaining their normal population size?
New York City biologists Dr. Georgia Silvera Seamans (@localecologist) and Dr. Jason Munshi-South (@urbanevol) posted their predictions on twitter.
On a local scale you may see a drop in the rat population if their food supplies disappear, e.g. street litter, restaurants, subway trash. It may encourage them to start moving around, and they may reproduce at a lower rate this Spring
— Jason Munshi-South (@urbanevol) March 22, 2020
And while it is currently unclear how urban populations will respond to this sudden decrease in anthropogenic food waste, natural experiments like this offer a (once in a lifetime, we hope) opportunity to study how urban animals respond to a sudden decrease in human activity. Populations that were surveyed before social isolation went into effect can be resampled shortly after social isolation policies are lifted. Depending on how long isolation occurs, stable isotopes can be used to assess how urban organisms shifted their diet and demographic models can shed light on how the population may have declined during social isolation helping us better understand the complex relationship between humans and urban animals.
Featured image: Image by Tim Bradshaw is licensed under CC BY-NC-SA 2.0
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