As a graduate Bobby Corrigan, who studied at Purdue University about two decades ago, spent the weekends in a commercial granary in Indiana. As part of his doctoral thesis, he observed how rats live, behave and reproduce after having followed around 10 different rat families on several floors of the extensive facility. The total population was about 150 rats.
After a few months, Corrigan decided to remove their food supply by meticulously cleaning up the loose grain.
At first there were loud arguments and fights between the rodents. The next nights there were real battles and even cannibalism. In a few days, almost all of the rats on the property had disappeared. They had either moved to a small town nearby or died before they had a chance.
Corrigan, a consultant and urban rat ecologist, now lives in New York City, where he advises city officials, airport workers, and pest control companies on how to deal with their rat problems. He says that his Indiana granary experiment has been repeated in cities across the country since the pandemic. Urban rats that have eaten their way through dumpsters and trash cans in alleys all their lives have seen their sources of food disappear. As a result, they change their behavior: looking during the day, sleeping in cars (chewing the wires, mistaking them for edible roots), penetrating apartment buildings, and – just like in this granary – rat-rat rat cannibalism, known as muricide.
“These animals become aggressive when they starve,” says Corrigan. “They attack each other. It’s pretty gross, but it’s life in the wild. “
This stressed behavior of rats has been reported in Chicago, where pest control experts report cannibalism and other unusual behaviors. in the tourist area of New Orleans on Bourbon Street; and in Philadelphia, where a pest control expert found a house with 20 rats that moved in after losing their food from local restaurants.
Rats usually live together in underground colonies about 50 to 75 feet from a food source. But since food has become scarcer, the range that each rat has covered has increased.
According to Jim Pesticks, chief pomologist for the National Pest Management Association, rodent control teams are reporting a big shift as rats expand their range to look for food.
“We have no data on rat populations increasingly“Says Fredericks.” What we see are some observations of rats that behave in a way that they don’t normally do. First of all, they act brazenly during the day in places where they have not been seen before. I suspect it has a lot to do with how people behave. These urban centers where many people would live are now ghost towns. “
City parks, tourist areas, and rows of restaurants, where a lot of people normally eat, are almost empty due to measures to block corona viruses. Fewer people mean less food for rats. And even in the suburbs, according to Fredericks, hungry rats, according to members of his organization, leave shopping malls to enter nearby houses in search of food.
The scarcity has also led to conflicts within each colony, he says. “Usually there is an alpha rat that gets first dibs on feed before the other,” says Fredericks. “A young adolescent has to wait for competition to increase. As more rats vie or eat less, tensions increase and there is a possibility that these rats may become violent with one another. “
While rats do not transmit the coronavirus, they can carry other diseases such as salmonella or leptospirosis, says Fredericks. These are many diseases that rats transmit directly to humans through infected urine or feces or indirectly by wearing ticks or fleas, which then bite humans and transmit the disease.