Latest news with #JonathanRichardson
Yahoo
07-02-2025
- Science
- Yahoo
Hordes of rats are infesting cities and the $27 billion a year problem is only getting worse
The saying goes that Kansas City in August is hotter than two rats in a wool sock, but it turns out the rising temperatures from climate change are fueling explosive growth in the global rat population. The warmer weather potentially expands the time they have to breed, putting cities on the back foot in their fight against the vermin. The latest chapter of New York's centuries-long war on rats has the city throwing everything at the problem—from enforcing new garbage laws, to enlisting bands of vigilante rat-hunters, to putting the rodents on birth control. But while the U.S.' largest city may be gaining ground in the anti-rat battle, the global fight is getting much harder, thanks to problems of humans' own making, new research suggests. Rising temperatures and more people living in dense environments are set to increase rat presence in some of the world's most important cities, suggests a study published last week in Science Advances. That's bad news for a future where ongoing climate change is projected to push already-elevated temperatures even higher. 'The warmer cities are getting, the faster their rat populations are increasing,' lead author Jonathan Richardson, assistant professor of biology at the University of Richmond, told Fortune. Richardson and his co-authors found that 11 of 16 global cities for which they obtained data saw their rat populations grow over a decade-long period, with New York, Washington, D.C., and Amsterdam having the biggest growth. Cities where temperatures were rising fastest showed the biggest rodent gains. High rates of urbanization (defined as low rates of green space) as well as larger populations were also objectively rattier, the researchers found. Only three cities— New Orleans, Louisville and famously clean Tokyo—saw rat populations drop over this period, Richardson said. As perhaps the most successful mammal in colonizing the globe after Homo sapiens, rats are humans' longtime foils and foes. A constant companion to people ever since the first urban settlements formed thousands of years ago, the rodents have metastasized into a $27-billion-a-year problem in the U.S. alone, damaging crops, chewing up wires, spreading at least 50 distinct diseases, and ripping up lawns, to name just a few issues. Warmer weather, especially in the winter, gives rats more opportunities to secure food and a potentially longer breeding window, the researchers noted. 'A rat doesn't hibernate, so if it has just a day or two to come above ground and replenish its food cache in its burrow;, that can bolster its survivorship and lead to more baby rats come spring,' Richardson said. 'A rat that is well fed in the winter can reproduce in the winter,' he added. Rats' remarkable multiplying properties are one reason that pest-control efforts have barely made a dent in urban rat populations: In good conditions, a female rat can produce a litter of a dozen or more pups every month. 'This species is exquisitely adaptive to reproducing and pumping out new rats,' Richardson said. The other is their status as a commensal mammal, meaning one that lives alongside people, 'feeding on our resources and exploiting our own mess that we create for ourselves.' In the Science Advances study, more urbanized environments, defined as those with less green space, were the second-biggest factor behind rat increases after warming temperatures. All that means that, to effectively deal with the problem, cities have to take a more proactive approach, Richardson said: Rather than trying to poison the rodents into oblivion, cities should make living environments more hostile to rats by eliminating easy food and comfortable breeding quarters. In this regard, he praised New York's efforts to put more trash in secured containers and limit how much time garbage spends on the street before being collected. An early effort in upper Manhattan has shown positive results and is expanding to more neighborhoods, he noted. CIties could also encourage homeowners to clean up their properties to make them inhospitable to rats, even fining those who don't comply. 'Sanitation is the number one strategy that we can use effectively to limit rats,' he added. 'Any city rodent management plan that doesn't start with sanitation and trash removal is bound to fail.' This story was originally featured on
Yahoo
31-01-2025
- Health
- Yahoo
More bad news for rat-infested cities: Climate change is making it worse
More rats: that's the latest indignity that climate change is dumping on major cities around the world, including in Canada's largest city, according to a new study from a group of global rodent and public health scientists. Growing rat populations are correlated with rising temperatures driven by global warming in at least 11 major cities across the world, according to the study. The cities seeing rat increases include Toronto, famously rat-prone New York City, and many other major centres like Washington, San Francisco and Amsterdam. The study's authors say it's a wake-up call for cities to move away from a whack-a-mole approach to dealing with rodent complaints. "I think every large city should have a dedicated team that focuses on nothing but rodents and the issues with rodents," said Jonathan Richardson, lead author of the study and an urban ecologist at the University of Richmond in Virginia. A rat in downtown Toronto. The city is working on a rat strategy. (Bruce Reeve/CBC) The study used data on public complaints and inspections about rats from 16 cities around the world. The 11 cities that saw significant increases in rats also experienced greater temperature increases over time, though that correlation doesn't prove the temperature caused the increase. Cities with more dense human populations and more urbanization also saw larger increases in rats. The research comes at a time when rats have become a big issue in Toronto, which is seeing a large increase in rodent-related complaints after a brief decline during the COVID-19 pandemic. City officials are currently working on a new strategy to proactively deal with the rats. "Even when you leave city hall or walk around city hall, you can see the burrows in the tree wells. I've walked along one of the streets and a giant rat ran past me in the middle of the day," said Alejandra Bravo, a Toronto city councillor who proposed the successful motion to build a rat strategy. "I think people need to see action." Why are rats thriving? Rats are resilient and remarkably adaptable to different environments, says Alice Sinia, entomologist with pest control company Orkin Canada. It makes biological sense that warmer temperatures would be helping them out, for three big reasons. The harsh winter acts as a sort of "nature's pest control," with the cold killing rats every year. Climate change has led to milder winters in Toronto, allowing greater numbers of rats to make it through the season. Urban ecologist Jonathan Richardson, right, has co-authored a study linking climate change to a growth in rat populations in several major cities, including Toronto. (Jamie Betts) Meanwhile, the warmer seasons have become longer, and that's when the rats breed and reproduce. Sinia says that could further boost their numbers. And finally, climate disasters themselves could be bringing rats closer to people and buildings. Sinia used the example of the floods in Toronto in July last year, caused by a line of storms that dumped rain on the city in rapid succession in a matter of hours. Studies suggest that Canada will see more extreme rain, with warmer air able to hold more moisture that it will dump in short, severe storms. The flash floods last year caused nearly a billion dollars in insured damages, flooding basements, highways and transit stations across the city. But apart from the damage, floods also overwhelm the city's sewer system — which are teaming with rats that get displaced. Alejandra Bravo, a Toronto city councillor who represents the ward of Davenport, has pushed the city to develop a rat strategy to respond to rising rodent complaints and sightings. (Michael Wilson/CBC) "Now instead of the underground sewers, they [the rats] will come to the surface and when that happens … they're going to start occupying other areas," Sinia said. "They're going into people's homes, structures… and they're going to have an opportunity to reproduce very fast." But none of this means people will just have to resign themselves to a rat-filled future, the experts said. Keeping up the fight Richardson, the study author, said that they key was a proactive rat strategy that addressed the root causes of infestations. That's similar to what the Toronto council is working on, according to Bravo. City staff will look at food disposal, managing construction sites, new approaches like birth control and other ways to manage the rat population on a larger scale. Ultimately, Richardson says, cities need to put more money and resources into fighting rats, because simply tolerating them is not a good option. A person holds up a rat that had been caught in Washington, D.C, one of several cities along with Toronto, New York and Amsterdam that showed a correlation between rising rat numbers and rising average temperatures. (Stefani Reynolds/AFP) "They carry at least 50 known zoonotic pathogens and parasites that can make residents sick in cities," he said. A zoonotic infection or disease is one that can transmit between animals and humans. "They also have mental health impacts for residents where if you're living alongside rats regularly and see them in your daily life, you tend to have worse mental health outcomes and feel less secure in your environment. "If we can reassess how much tolerance we have for rats in our everyday daily life as we're walking around, maybe that applies some pressure to the city governments and advocates for more resources to knock these populations back."
CBC
31-01-2025
- Science
- CBC
More bad news for rat-infested cities: Climate change is making it worse
Social Sharing More rats: that's the latest indignity that climate change is dumping on major cities around the world, including in Canada's largest city, according to a new study from a group of global rodent and public health scientists. Growing rat populations are correlated with rising temperatures driven by global warming in at least 11 major cities across the world, according to the study. The cities seeing rat increases include Toronto, famously rat-prone New York City, and many other major centres like Washington, San Francisco and Amsterdam. The study's authors say it's a wake-up call for cities to move away from a whack-a-mole approach to dealing with rodent complaints. "I think every large city should have a dedicated team that focuses on nothing but rodents and the issues with rodents," said Jonathan Richardson, lead author of the study and an urban ecologist at the University of Richmond in Virginia. The study used data on public complaints and inspections about rats from 16 cities around the world. The 11 cities that saw significant increases in rats also experienced greater temperature increases over time, though that correlation doesn't prove the temperature caused the increase. Cities with more dense human populations and more urbanization also saw larger increases in rats. The research comes at a time when rats have become a big issue in Toronto, which is seeing a large increase in rodent-related complaints after a brief decline during the COVID-19 pandemic. City officials are currently working on a new strategy to proactively deal with the rats. "Even when you leave city hall or walk around city hall, you can see the burrows in the tree wells. I've walked along one of the streets and a giant rat ran past me in the middle of the day," said Alejandra Bravo, a Toronto city councillor who proposed the successful motion to build a rat strategy. "I think people need to see action." Toronto councillors push for rat reduction strategy Why are rats thriving? Rats are resilient and remarkably adaptable to different environments, says Alice Sinia, entomologist with pest control company Orkin Canada. It makes biological sense that warmer temperatures would be helping them out, for three big reasons. The harsh winter acts as a sort of "nature's pest control," with the cold killing rats every year. Climate change has led to milder winters in Toronto, allowing greater numbers of rats to make it through the season. Meanwhile, the warmer seasons have become longer, and that's when the rats breed and reproduce. Sinia says that could further boost their numbers. And finally, climate disasters themselves could be bringing rats closer to people and buildings. Sinia used the example of the floods in Toronto in July last year, caused by a line of storms that dumped rain on the city in rapid succession in a matter of hours. Studies suggest that Canada will see more extreme rain, with warmer air able to hold more moisture that it will dump in short, severe storms. The flash floods last year caused nearly a billion dollars in insured damages, flooding basements, highways and transit stations across the city. But apart from the damage, floods also overwhelm the city's sewer system — which are teaming with rats that get displaced. "Now instead of the underground sewers, they [the rats] will come to the surface and when that happens … they're going to start occupying other areas," Sinia said. "They're going into people's homes, structures… and they're going to have an opportunity to reproduce very fast." But none of this means people will just have to resign themselves to a rat-filled future, the experts said. Keeping up the fight Richardson, the study author, said that they key was a proactive rat strategy that addressed the root causes of infestations. That's similar to what the Toronto council is working on, according to Bravo. City staff will look at food disposal, managing construction sites, new approaches like birth control and other ways to manage the rat population on a larger scale. Ultimately, Richardson says, cities need to put more money and resources into fighting rats, because simply tolerating them is not a good option. "They carry at least 50 known zoonotic pathogens and parasites that can make residents sick in cities," he said. A zoonotic infection or disease is one that can transmit between animals and humans. "They also have mental health impacts for residents where if you're living alongside rats regularly and see them in your daily life, you tend to have worse mental health outcomes and feel less secure in your environment. "If we can reassess how much tolerance we have for rats in our everyday daily life as we're walking around, maybe that applies some pressure to the city governments and advocates for more resources to knock these populations back."
CNN
31-01-2025
- Health
- CNN
These cities have big rat problems, and there's one thing to blame
There's a saying that in a big city you are never more than six feet away from a rat. It's an urban myth, but scientists are warning cities across the globe are becoming far rattier, and the boom is primarily driven by one factor: climate change. Jonathan Richardson, a biology professor at the University of Richmond, decided to research urban rat trends after seeing media reports of rats taking over cities. These tended to focus on single locations and 'usually without a lot of hard data,' he told CNN. He and his team decided to change that. They requested rat stats from the 200 biggest US cities by population, but found only 13 had the quality long-term data they needed. To give more geographical range, the researchers also included three international cities: Toronto, Tokyo and Amsterdam. The data collected spanned an average of 12 years and comprised rat sightings, trappings and inspection reports. It revealed 'significant increasing trends' in rat numbers in 11 of the 16 cities, according to their study, published Friday in the journal Science Advances. Washington DC, San Francisco, Toronto, New York City and Amsterdam experienced the biggest growth. Just three saw declines: New Orleans, St. Louis and Tokyo. The study linked rat increases to several factors, including high population densities and low amounts of urban vegetation, but the predominant influence was warmer average temperatures. Rats are small mammals and limited by the cold, Richardson said. Warmer temperatures, especially in the winter, give them longer to be outside foraging and, crucially, longer to reproduce through the year. A warmer climate can also extend growing seasons, providing rats more food as well as vegetation to hide in, said Michael Parsons, an urban field ecologist and wild rat expert who was not involved in the research. 'Even scents of food and rubbish can travel farther in warmer weather,' he told CNN. Burgeoning rat populations are a big problem for cities. Rats damage infrastructure, contaminate food, and can start fires by gnawing through wires. They cause an estimated $27 billion of damage each year in the US, according to the report. They are a health hazard, too. 'Rats are associated with more than 50 pathogens that affect people,' which they transfer through their urine, feces, saliva nest, materials and parasites, said Matt Frye, a pest expert at Cornell University, who was not involved in the research. Some of these can be severe, such as leptospirosis, also called Weil's disease, which can cause kidney and liver damage and even death without treatment. There is also increasing evidence rats have 'huge mental health impacts' on the people living around them, Richardson said. Even among the rattiest cities identified in the study, Washington, DC, stood out. It had a 1.5 times greater growth in rat populations than New York City. The tell-tale sign of a rat problem in DC is a hole chewed through a hard plastic trash can. 'The only way you can rodent proof a trash can is not to put food in it,' said Gerard Brown, who runs the city's rodent control program. Last year was DC's hottest on record — bad news for attempts to control rats. Brown is hoping the cold snap in December and January will help cull the population. 'Cold acts as a natural exterminator,' he said. Brown and other city officials attempted a rat birth control pilot project several years ago but abandoned it after inconclusive results. The rats had to consume a liquid birth control daily, an impossible task to guarantee. Brown said DC's numbers could be so high because the city encourages residents to call in each rat sighting. Public reports of rats are very useful but can be flawed, said field ecologist Parsons. People normally only make a call when they see something 'unusual,' he said, and not when rats are expected in any given area. It is incredibly hard to pin down accurate urban rat numbers, Parsons added. 'Rats are small, cryptic and usually nocturnal.' Richardson said the high number of rats in some cities is no indictment of authorities' commitment to tackling the problem, but rat-reduction efforts are often underfunded. Lessons can be learned from the three cities in the study that reduced rat populations, he said. He chalks their success up to campaigns informing residents how to avoid attracting rats and making city resources available to help. Richardson also encouraged authorities to move away from lethal control, 'because it's just responsive to infestations that are already there,' and think more about how to take away access to what rats rely on, such as food waste, garbage access and debris piles. The findings are a wake up call about the challenge rats may pose in a warmer world, Richardson said. 'If you don't have a handle on this, it's only going to get worse. You don't want to be like Sisyphus pushing that boulder up a hill.' In DC, Brown said he is optimistic about the city's battle to keep its rats under control. 'Nobody in the world thinks we are totally going to get rid of rats, but we can reduce them to a manageable level,' he said. 'The goal is to control and reduce.'
Yahoo
31-01-2025
- Science
- Yahoo
Oh, great: Rat populations are surging as cities heat up
Rats are in many ways better adapted to cities than the humans that built them. While urbanites struggle with crowds, sparse parking spaces, and their upstairs neighbors stomping around at 4 a.m., rats are living their best lives. Huddled safely underground, they pop up at night to chew through heaps of food waste in dumpsters and hot dogs left on stoops. Now scientists have found yet another gnawing advantage for rats. A study published on Friday in the journal Science Advances found that as temperatures climb in cities, rat populations are growing, even as city dwellers suffer. 'In cities that have experienced the fastest warming temperatures, they tended to have faster increases in their rat numbers as well,' said Jonathan Richardson, an urban ecologist at the University of Richmond and lead author of the paper. 'Females will reach sexual maturity faster. They're able to breed more, and typically their litters are larger at warmer temperatures in the lab.' The analysis used public complaints about rats and inspection records from 16 cities between 2007 and 2024, which collectively served as a proxy for rat populations. In 11 of those cities, rat numbers surged during that period. The winner of the Most Rats Gained award goes to Washington, D.C., with a 390 percent increase according to the city's last decade of data, followed by San Francisco (300 percent), Toronto (186 percent), and New York City (162 percent). Meanwhile, a few cities actually saw their rat populations decrease, including New Orleans, Tokyo, and Louisville, Kentucky, due in part to more diligent pest control. 'It's a first step at answering this question, that if you get a bunch of rat scientists into a room we're bound to ask each other: How might climate change play into rat populations?' said Kaylee Byers, a health researcher at Simon Fraser University in Canada, who wasn't involved in the study. Beyond the physiological factors that influence breeding, rat behavior changes with temperature, too. If it's too cold out, the rodents tend to huddle underground — in basements, sewers, and really anywhere else in the subterranean built environment. Once it warms up, rats emerge and gorge, but also bring food back to their nests to store in caches. Climate change is also altering the timing of seasons: If the weather stays warmer a week or two longer into the early winter, and if spring comes a week or two earlier, that's more time to forage. 'Rats are really well-adapted to take advantage of a food resource and convert that to new baby rats that you'll see in your neighborhood,' Richardson said. While temperatures are rising globally, they're getting particularly extreme in cities thanks to the urban heat island effect. Buildings and concrete absorb the sun's energy, raising temperatures up to 27 degrees Fahrenheit higher than in surrounding rural areas and releasing that heat at night. That's especially dangerous in the summer for urbanites during prolonged heat waves. But in the winter, that bit of extra heat could be helping rats. Rising temperatures were the dominant force helping rat populations grow, but they weren't the only factor, the study found. Urban human populations are exploding around the world, and they're wasting a lot of food for rats to find. As cities expand around their edges, they have to add new infrastructure, which rats colonize. And when cities build new sewer systems to handle more people, they often leave the old ones in place, providing a welcoming environment for rats. 'The vestigial urban infrastructure that's down there, it doesn't really matter for us,' Richardson said. 'But for a rat, that's like a free highway.' The researchers also found that cities with fewer green spaces had higher growth of rat populations. It's not clear yet why that might be, they said. No two green spaces are the same: A small urban park might teem with rats because office workers flock there to eat lunch, then drop their leftovers in trash bins, whereas the interior of a larger space like Central Park might provide less food and fewer places for rodents to hide from predators like hawks and coyotes. So how can a city control its rat population as temperatures rise? For one, by getting more data like the numbers found in this study. 'You can't manage what you can't measure,' said Niamh M. Quinn, who studies human-wildlife interactions at the University of California Division of Agriculture and Natural Resources but wasn't involved in the research. 'We live in an infinite sea of rats, so you can't just manage small pockets. You have to have municipal rat management.' New Orleans has succeeded by being proactive, Richardson said, such as with education campaigns teaching building owners how to rat-proof their structures, and insisting that if they do see rats to call the city for eradication. Cities can't just poison their way out of this problem without hurting other animals, he said, because that poison makes its way into the stomachs of rat-eating predators. 'Right now, our approach to rat management is very reactive,' Byers said. 'We're not thinking about the future at all. We need to do that if we're actually concerned about rats, and if we want to manage the risks associated with them.' This story was originally published by Grist with the headline Oh, great: Rat populations are surging as cities heat up on Jan 31, 2025.
