What happens to rats living in a city when biblical flooding hits?

Mice scurry around stored grain on a farm near Tottenham, Australia, on May 19, 2021. Vast tracts of land in Australia's New South Wales state are being threatened by a mouse plague that the state government describes as "absolutely unprecedented." Just how many millions of rodents have infested the agricultural plains across the state is guesswork. (AP Photo/Rick Rycroft)

During natural disasters like hurricanes or catastrophic flooding, the focus is appropriately on the impacts on human life. Along with deaths and injuries, damages to homes and businesses impact humans and are rightly the center of attention when discussing the toll a storm inflicts.

But humans aren't the only creatures impacted by a storm, and as much as people may try to pretend like they aren't there, our rodent neighbors feel the impacts on their homes as well.

Millions of rats live within and under every major city, including storm-prone areas such as Houston, New Orleans, Atlanta, Philadelphia and New York City. In the Big Apple, urban legends have speculated for years that there are as many rats as people, although a statistical study from 2014 suggested that may not be the case.

While one might think that a catastrophic storm in a city would wreak even more havoc to underground rodent populations, experts say: not so fast.

Nature knows Mother Nature, as expert Janet Hurley told AccuWeather.

"Rats, like everybody else, when you get a storm, they tend to get displaced," she said. "Nature knows when Mother Nature is going to throw them a curveball."

FILE - In this Jan. 27, 2015, file photo, a rat crosses a Times Square subway platform in New York. It's a problem practically as old as New York itself, how to handle the untold legions of rodents residing in the city. Last year, the city received more rat-sighting calls than ever before, and officials, led by a city rat scientist, are trying new and innovative ways to control the population, with mixed results. (AP Photo/Richard Drew, File)

Hurley is a certified entomologist with the Texas A&M AgriLife Extension Service and credited animals like rodents, birds and insects for being more equipped for natural disasters than most humans.

But like the two-legged earthlings, there are also many aspects of storms that displace incalculable animal populations.

"Almost all of nature is probably much better equipped because they do understand. Some of their stuff is intrinsic to barometric pressure. Birds know and bats know, rats know, even your dog can sometimes tell you got a storm coming before you know you have a storm coming," she said. "But I mean they can't deal with a storm surge. I don't think anyone is prepared for when that water blows up and it spills over."

With a devastating storm like Ida, which caused destruction not only as a hurricane in the Southeast but also as a tropical rainstorm in the Northeast, that spilling water can quickly become inescapable.

Those floodwaters led to dozens of fatalities in the Northeast, 10 of which occurred in New York City. After more than 3 inches of rain fell in a 60-minute span, disaster ensued in the city, rats included. Some experts speculated that the rodent death toll could have been in the hundreds of thousands.

"With this particular storm, any rats that were in the sewers were either crushed by the current or were swept out into the rivers," Bobby Corrigan, former ​​rodentologist for the NYC Department of Health, told the Gothamist. "I can't imagine they would've survived."

But in many other storms, rats not only survive, but they also thrive in the ensuing disaster areas.

While many tragic storm deaths occur in the South when residents get trapped in their attics or in the Northeast when residents get closed in from flooded basements, being so small and agile can be a life-saver for rodents, who are strong swimmers.

Resilient rodents have gone viral in New York City in years past for snagging pieces of pizza in subway stations (multiple times), dragging entire bags of trash and even munching on an avocado.

But in the face of a storm, the city's rats proved in 2018 that they can be crafty in dodging floodwaters as well. One rodent, nicknamed "Flood Rat," gained internet fame for brilliantly hiding behind a support beam.

"Yes, some can drown, but some can swim and some just get pushed out of the way," Hurley said. "In other words, wherever the water goes, like a boat, things also can get just dislodged," she explained. "Rodents are no different, they've just been moved about. They don't always all die, some of them survive and then some of them move."

Michael Blum, an ecologist at the University of Tennessee, studied the impacts on rat populations in New Orleans following Hurricane Katrina in 2005. Not only did the resilient rodents survive the costliest natural disaster in U.S. history, but they've actually thrived in the years since.

According to a publication authored by Blum and other ecologists from the University of Tennessee, rodent "prevalence was higher in areas that sustained more severe flood damage and abandonment," in the decade that followed the Louisiana hurricane.

"It's sort of counterintuitive," Blum told CNN. "You think, in these flood-affected areas, these things should be wiped out. But really, things get wiped out, but they come back very quickly. They can become much more abundant than they were prior to flooding."

Mike Miller, Katy Quigly and Clarence White III, members of the abandoned buildings outreach team, of Unity Of Greater New Orleans, counsel homeless squatters on housing options, as they search abandoned, blighted buildings in New Orleans, Tuesday, Jan. 18, 2011. (AP Photo/Gerald Herbert)

Among a variety of post-storm reasons, experts point to one specific cause for that abundant population return: trash.

As pointed out in Blum's study, efforts to rebuild or repair damaged city infrastructure heavily rely on the clearing out of debris. In areas where the destruction is left abandoned, new rodent populations can also settle in without human disruption, sometimes claiming irreparable homes for years before restoration attempts begin.

In the case of Katrina, that infrastructure was damaged so badly that it took an incredibly long time for curbside debris and trash to be collected, providing ample resources for rodent populations in the form of stray refrigerators, boxes and furniture.

A resident dumps debris while gutting his flooded home in the aftermath of Hurricane Ida in LaPlace, La., Tuesday, Sept. 7, 2021. (AP Photo/Gerald Herbert)

"Think about what rats need - food, water, harborage," Hurley said. "OK, well we've just now given them everything they need on the curb, and at the same time we're still living there."

According to Claudia Riegel, director of the New Orleans Mosquito, Termite and Rodent Control Board, the rat population was increasing exponentially after Katrina, she told CNN.

"No matter if it's Houston or New Orleans or the Northeast, you get all that stuff that's gotten flooded inside a building and what do we do with it? We cart it outside and we drop it on the curb and how long does it sit there? Well, not a couple of days, it's generally several weeks," Hurley told AccuWeather.

Such a population explosion can also be a health hazard, Hurley said.

The main type of rodents, which she called "the three bad guys," are hallway rats, roof rats and the house mouse. All three of them live in close proximity to humans who happen to be in possession of a lot of things that can help them thrive. This is why the rodents always return: "Because we just give them extra garbage to play with," she said.

On top of the grossness factor, that returning population also comes with health dangers, particularly in the urine and feces the rodents leave behind.

Hurley encourages people to keep the rodents far from the home by making sure that trash and debris are kept at least 50 feet to 100 feet away from the home.

"Wear your gloves, wear that face mask," she said, adding that face masks that help prevent respiratory illnesses like COVID-19 are equally helpful at protecting against pathogens. "If you're cleaning up, make sure you just don't touch the stuff and definitely watch where you put your trash."

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