Possible side effect of warmer weather: more mice in homes

At herhome in Rockford, Illinois, Rita Davisson said the “one or two” mice she normally sees during the waning winter months “have turned into more like 10 or 15” in the last couple 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 the more than 30 years she’s lived in her house.

“They’re sneaking around 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 the white-footed mouse, the most abundant small rodent found throughout much of the eastern U.S. and Canada, making more work for pest control experts.

Above-average temperatures were recorded across most eastern and central U.S. states last winter. Since 1970, average winter temperatures have increased by at least one degree Fahrenheit in every state, with states in the Northeast and the Great Lakes region warming by more than 3 degrees.

While the mouse population typically decreases 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.

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