Watch out for rats: This is the reason why their numbers are increasing in US cities according to experts
Scientists sorted through data from more than a dozen US and foreign cities to determine what is driving the increase in rat populations in urban areas.
Where there are a lot of humans these days it’s a good bet that there are rats as well. It’s impossible to know exactly how many of these furry rodents there are but their numbers worldwide are believed to be in the billions. In China, there is believed to be roughly two for every human in the country according to WorldAtlas.
There are stories abound of rats taking over cities, especially when they come out of the shadows. And the problem is likely to become worse according to a new study published Friday in the journal Science Advances.
Humans are rats best friends: the hairier side of climate change
Not only have humans helped rats expand around the world, but our urban environments provide shelter from the elements and plenty of sustenance from food waste and trash. Additionally our reliance on fossil fuels, and the climate change it is bringing about, may also be giving these rodents a leg up to multiply their numbers according to findings by a group of researchers led by Jonathan Richardson, professor at the University of Richmond.
They looked at data on public sightings, rat trappings and inspection reports from 16 cities that spanned an average of 12 years to see what factors were affecting rat population growth. Their research revealed that eleven of them “had significant increasing trends in rat numbers,” among them Washington DC, New York, and Amsterdam, and only three of them, New Orleans, Louisville and Tokyo, saw declines.
The cities that saw larger increases in rats were also those experiencing greater temperature increases along with dense human populations and more urbanization. The two factors combine to provide not only more food availability but also expanded seasonal activity periods allowing rats time to have additional litters.
Less cold spells, which can act a natural control on rat populations by culling their numbers, also means fewer opportunities for exterminator to take advantage of when they move indoors and have lower birth rates.
Growing rat populations present risk to human health
Not only are rats destructive, damaging infrastructure, consuming and contaminating food supplies causing an estimated $27 billion in damaging the in US alone, but they are also vectors of disease. They host and transmit over 50 pathogens including bubonic plague, murine typhus and leptospirosis.
“At some point there’s going to be — hopefully not, but potentially — the perfect storm, where we have all these people, all these rodents [and] not enough tools in our toolbox to manage them,” Niamh Quinn, a human-wildlife interactions advisor at the University of California Division of Agriculture and Natural Resources in Irvine told Science News.
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