DENVER (KDVR) — According to Colorado State University researchers, yes, tourists are killing off ground squirrels.

A new report claims Colorado’s population boom and tourism push into the Rocky Mountain National Park killed off ground squirrels, particularly females. The study was done in the Department of Fish, Wildlife and Conservation Biology, part of the Warner College of Natural Resources at CSU.

The study used 31 years’ worth of data about golden-mantled ground squirrels and traffic volume along County Road 317 in Gunnison County.

On average, about 5% of the squirrel population was road-killed each year. The roadkill rates rose during tourist seasons, which researchers tie to the number of visitors to a nearby destination.

Females were road-killed in higher numbers.

“Contrary to prediction, adult females were the demographic group most affected: nearly twice the proportion of adult females versus adult males died in roadkill events,” the report reads. “Though we predicted that males might be more at risk from their wide-ranging exploratory behavior, their road crossing may occur more during the mating season in April and May when traffic volume is absent or low.”

CSU researchers estimate that as many as one in every 10 female ground squirrels died in roadkill events.

Potentially, this is more disastrous for the ground squirrel population than if more males died. Not only do ground squirrels lose females to breed new ones, but the young of the female ground squirrels may die as well without their mother.

Since ground squirrels are crucial for Rocky Mountain ecology, researchers suggest a few fixes including bussing people to tourist destinations, limiting the number of cars on the road and additional signage warning drivers of the potential mortality to animals.