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The climate conundrum: Does weather impact rat breeding?

Washington, D.C., warmed more than 2 degrees Fahrenheit over the past century, sparking debate about the temperature’s impact on the District’s ever-growing rat population.

Since 2010, the area has seen five of its six hottest summers on record, and the changing rainfall and weather patterns are expected to increase flooding and drought. According to the Environmental Protection Agency, higher temperatures and water level changes are expected to increase flooding, storms and the amount of sewer overflow, leading to possible ecological change.

One of those changes is the rat population. In an emailed statement sent to The Wash, Mayor Muriel Bowser said there’s been an increase in rodent activity in the District in recent years.

“This problem is not unique to Washington, D.C. and it is believed to be the result of warmer winters,” Bowser said.

Lisa Benton-Short, the program director for sustainability at George Washington University, said all urban areas are dealing with the impacts of climate change, but she attributed the problem in D.C. to the city’s inefficient management of food waste, not climate change.

“I really don’t know exactly how I would correlate more rats with climate change,” Benton-Short said.

According to the DC Department of Health, rat populations ebb and flow depending on the season. Rodent populations are lowest in the winter when breeding is kept to a minimum. Annual breeding usually occurs in March as the weather starts to get warmer. With a gestation period of about three weeks, rats can have anywhere from five to 10 pups (baby rats) and can have three to six litters in a lifetime. Rats see another peak breeding period in September when temperatures cool in the fall.

A study published by the Journal of Urban Ecology says rodent-related risks could be spiking due to human urbanization, climate change and a lack of combatting the rat issue.

Chelsea Himsworth is a veterinarian and a member of the Vancouver Rat Project, which is a study within the Canadian Wildlife Health Cooperative. It looks to understand the variables of rats in the urban area and found that environmental impacts on rats have yet to be fully understood. The study found that the factors affecting rat presence the most were land use, building conditions, presence of garbage and socioeconomics.

D.C. is expected to see a white winter and colder-than-average temperatures this year, according to Doug Kammerer, NBC 4 Chief Meteorologist. Whether the anticipated flurries result in a change in the District’s rat population remains to be seen.

The Wash Staff

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