At her home in Rockford, Illinois, Rita Davisson said “one or two” mice she normally sees during the waning winter months “have turned into more than 10 or 15” over the past two years , and scientists say the warmer weather might have something to do with it.
The 66-year-old said the influx prompted her to contract a pest control service for the first time in more than 30 years that she had lived in her home.
“They sneak into the basement, the garage, my backyard,” she said. “The one trap I have just hasn’t been enough lately.”
Researchers say warming temperatures and milder winters have increased the population of white-footed mice, the most abundant small rodent in much of the eastern United States and Canada, which demands more work to pest control experts.
Last winter, above average temperatures were recorded in most states in the eastern and central United States. Since 1970, average winter temperatures have risen by at least one degree Fahrenheit (0.6 Celsius) in every state, with states in the Northeast and the Great Lakes region warming by more than 3 degrees F (1. 7C).
While the mouse population typically declines during long winters, warmer winters fueled by climate change mean fewer mice are dying before spring, said Christian Floyd, a wildlife biologist at the University of Rhode Island.
“These little mammals spend their whole lives shivering. They lose heat so quickly,” Floyd said. “When the winter is milder, they survive better. Mice don’t have to shiver as much and they’re also less likely to starve because they have more ability to hunt for food.”
Susan Hoffman, associate professor of biology at the University of Miami in Oxford, Ohio, said the white-footed mice migrated past a transitional forest region that has long served as a dividing line for many species. , noting that they have grown “surprisingly fast”. in North America – about 125 miles in 30 years, 15 times further than expected.
The white-footed mouse, which historically proliferated from the Tennessee Valley across the northern Atlantic coast, has already extended its northern limit into Quebec, Hoffman said. By 2050, the mouse population is predicted to have migrated north in greater numbers, especially as global warming also pushes their preferred forest habitats further north.
This migration has also been documented with other species, including chipmunks, flying squirrels and prairie jumping mice, she said.
“Multiple lines of evidence indicate that warmer temperatures and global climate effects allow (white-footed mice) to survive farther north,” Hoffman said, adding that humans are also likely responsible for the unintentional transport of mice to the north in cars, boats and RVs.
Scientists say the spread of rodents 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 forces pest control technicians to spend more time eliminating food sources and pests. entering homes to control mouse populations.
This is already the case in Indiana, where Allie Dickman, director of AAA Pest Control, said technicians have seen an increase in mouse calls this winter. Calls for more mouse services in rural and suburban homes, as well as urban buildings, continued into the spring.
“Right now I’d say 30% to 40% of our calls involve mice, which is quite surprising considering the time of year,” Dickman said. “They’re just adapting and growing more…and there’s more.”
Experts also warn of even greater implications for public health, given that white-footed mice are natural reservoirs for Lyme disease bacteria, which can then infect ticks capable of transmitting Lyme disease. Lyme to humans.
The bacterial disease, which can cause fever, fatigue, joint pain and rash, as well as more serious joint and nervous system complications, is the most common vector-borne disease in the United States.
Maine, Vermont and New Hampshire have so far seen the largest increases in reported cases, which the US Environmental Protection Agency has attributed, in part, to climate change.
Elliot Smythe, 53, a farm owner near Randolph, Vermont, said he was paying more attention to the growing number of mice and ticks and the property after his 15-year-old son contracted Lyme disease last fall.
“Living in a more rural area like me, the mice didn’t bother me that much,” Smythe said. “But when they keep coming and they become a nuisance… well now I have a problem.”
Over time, moving mice north could mean more southern parts of the United States will see fewer rodents, Floyd said, but parts of the Midwest, New England and Canada could see them in greater number.
“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 due to climate change could also play a role. There is a lot more to learn.”