How brown rats crawled from ships and invaded North American cities – Science News (Trending Perfect)


Brown rats are the undisputed winners in the real rat race.

New research suggests that they crawled off ships that arrived in North America earlier than previously thought, outgunning their rodent rivals, infuriating and disgusting generations of city dwellers, and becoming so ubiquitous that they are known as common mice or voles. Street or street rats. Sewer rats.

It didn't take long for them to ward off the black rats that likely arrived with Columbus and flourished in colonial cities.

After first appearing on the continent before 1740, brown rats took over the East Coast from black rats “within just a matter of decades,” said Michael Buckley, one of the authors of the study published Wednesday in the journal Science Advances.

Brown rats are larger and more aggressive than black rats, and want to be close to human populations, said Matthew Fry, a researcher and community educator at Cornell University's New York State Integrated Pest Management Program.

From this research, “we know a more precise time of when they arrived then what they were doing once they got here,” said Fry, who was not involved in the study. “Having that picture of groups of mice helps us better understand what they do, and perhaps how we “Manage them.”

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Buckley, of the University of Manchester in the United Kingdom, said that none of the rat species are native to North America. Scientists used to think that brown rats arrived around 1776. But the new study pushes that date back more than 35 years.

Buckley and his colleagues analyzed rodent bones excavated by archaeologists. The remains came from 32 settlements in eastern North America and the Gulf of Mexico dating from the founding of Jamestown in 1607 through the early 1900s. The other samples were from seven shipwrecks dating from around 1550 to 1770.

The data suggest that transatlantic shipping networks “essentially functioned as rat highways,” with brown rats gaining an early foothold in coastal shipping hubs, said Ryan Kennedy, an author of the study at Indiana University who researches animal remains at archaeological sites.

The researchers suggest that one possible reason for their dominance is that they ate food that the black rats would otherwise have consumed — which may have led to reduced reproduction among the black rats. Historical anecdotes support this finding, describing the near disappearance of black rats from cities in the 1830s.

Today, both types of mice are found in North American cities, although brown mice are more common. Some urban centers are particularly bypassed. New York City, for example, Last year I hired a “rat czar”. “To address a growing problem there.

Biggest issue? Mice can carry diseases. Brown rats are known to spread a bacterial disease called leptospirosis, which is caused by bacteria found in the urine of infected animals. They can also help spread murine typhus and foodborne germs such as salmonella.

Knowing which type of rat is leading the pack helps cities control pests, even if it sometimes doesn't seem that way, experts said.

For example, brown mice like to hang out on or near the ground rather than in trees or other high places, where black mice often prefer to stay.

Black and brown rats are omnivores, but brown rats are particularly fond of animal products — meaning that reducing those in food waste “should have a greater chance of reducing the value of urban habitat for rat populations,” Buckley said.

All efforts to reduce available food waste help, Fry said.

“Food availability is the number one reason for the existence of brown rats,” he said. “Any efforts to prevent mice from accessing food sources are effective.”

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