Climate change means more rats, demand for pest control

INDIANAPOLIS (AP) – At her home in Rockford, Illinois, Rita Davisson said the “one or two” mice she normally sees during the winter months “have turned into more than 10 or 15” in the past two years, and the scientists say warmer weather may have something to do with it.

The 66-year-old said the influx prompted her to hire a pest control service for the first time in more than 30 years of living in her home.

“They’re hiding in the basement, in the garage, in my backyard,” she said. “The only trap I have hasn’t been enough lately.”

The researchers say warmer temperatures and milder winters have boosted the population of the white-footed mouse, the most abundant small rodent found across much of the eastern US and Canada, making it more work for pest control experts.

Above-average temperatures were recorded in most eastern and central US states this past winter. Since 1970, average winter temperatures have increased by at least one degree Fahrenheit (0.6 Celsius) in all states, with states in the Northeast and the Great Lakes region warming by more than 3 degrees F (1.7 C).

While the mouse population typically declines during long winters, warmer winters, fueled by climate change, mean fewer mice die before spring, said Christian Floyd, a wildlife biologist at the University of Rhode Island.

“These small mammals spend their entire lives trembling. They lose heat so fast,” Floyd said. “When you have a milder winter, they will survive better. Rats don’t have to shake as much and are also less likely to starve to death because they are better able to hunt for food.”

Susan Hoffman, an associate professor of biology at the University of Miami in Oxford, Ohio, said the white-footed mice migrated through a region of transitional forest that has long served as a dividing line for many species, noting that they expanded “surprisingly fast.” ”. in North America – about 125 miles in 30 years, 15 times further than previously expected.

The white-footed mouse, which historically proliferated from the Tennessee Valley to the north Atlantic coast, has now expanded its northern limit to Quebec, Hoffman said. By 2050, the mouse population is predicted to have migrated north in even greater numbers, especially as the warmer climate also pushes their preferred forest habitats northward.

This migration has also been documented with other species, including chipmunks, flying squirrels and jumping mice, she said.

“Multiple lines of evidence indicate that warmer temperatures and general weather effects are allowing (white-footed rats) to survive further north,” Hoffman said, adding that humans are also likely responsible for unintentionally carrying some rats to the north. the north in cars, boats and trailers.

Scientists say the rodent spread could mean more mice in and around homes. Michael Bentley, director of training and education for the National Pest Management Association, noted that increased mouse activity also requires pest management technicians to spend more time eliminating food sources and entry points into homes to control mouse populations. .

That’s already the case in Indiana, where Allie Dickman, director of AAA Pest Control, said technicians have seen an increase in rat calls this winter. Calls for more rat services in rural and suburban homes, as well as urban buildings, continued into the spring.

“Right now, I would say 30% to 40% of our calls involve rats, which is pretty surprising given the time of year,” Dickman said. “They are just adapting and expanding more… and there are more of them.”

Experts also warn of even greater public health implications, as white-footed mice are natural reservoirs of Lyme disease bacteria, which can infect ticks capable of transmitting Lyme disease to people.

The bacterial disease that can cause fever, fatigue, joint pain, and rashes, as well as more serious joint and nervous system complications, is the most common vector-borne disease in the U.S.

Maine, Vermont and New Hampshire have so far experienced the biggest increases in reported cases, which the US Environmental Protection Agency has attributed, in part, to climate change.

Elliot Smythe, 53, who owns a farm near Randolph, Vermont, said he is paying more attention to the growing number of mice and ticks and to the property after his 15-year-old son contracted Lyme disease last fall.

“Living in a more rural area like myself, I didn’t care much for rats,” Smythe said. “But when they keep coming and they become a nuisance… well, now I have a problem.”

Over time, the mice’s northward movement could mean that the southernmost regions of the US will see fewer rodents, Floyd said, but areas in the Midwest, New England and Canada could see them in greater numbers.

“We’re going to need more research to better understand where and how fast (the mice) are moving,” he said. “We will also need to learn more about how wetter conditions from climate change can also play a role. There is much more to learn.”


Casey Smith is a staff member of the Associated Press/Report for America Statehouse News Initiative. Report for America is a non-profit national service program that places journalists in local newsrooms to report on top secret issues. Follow Smith on twitter. ___ Associated Press climate and environmental coverage is supported by several private foundations. See more about the AP climate initiative here. The AP is solely responsible for all content.

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