It feels like deer are showing up everywhere lately — our yards, along neighborhood sidewalks, and crossing busy roads — you’re not just imagining it.
New research from David Stoner, an extension specialist at Utah State University, shows that Utah’s ongoing drought is pushing mule deer out of their usual habitats and into irrigated farmland and neighborhoods in search of food and water.
The research, funded by NASA and the Utah Division of Wildlife Resources, used data from an experimental sensor aboard the International Space Station to track where the deer were going.
By measuring how much water was moving through plants, the tool let researchers see when the landscape became too dry to support wildlife.
Stoner said the tipping point is when evapotranspiration exceeds just one millimeter per day.
“Evapotranspiration is the amount of water that a plant pumps out of the soil and is evaporated into the sky," he explained. "It sounds like a very small amount of water, but it's critical.”
He added that dry, withered vegetation provides less nutrition and takes more energy for deer to digest. That pushes them to take bigger risks to find better food, bringing them closer to roads, fences, pets, and people.
In a typical year, Stoner said mule deer spend more than half their time in natural shrublands and only about 6% in croplands.
But during extreme drought, which has become a new normal for Utah, the time deer spend outside of their natural habitat can double. That leads to deer facing dangers like vehicle collisions and dogs.
Meanwhile, farmers and homeowners are left dealing with damaged crops and landscaping. Plus, Stoner added, the deer may attract further attention from certain unwanted visitors with claws and teeth.
“With deer in these urban and agricultural areas, the things that prey on them may follow as well," he said, "so we may have mountain lions following them into these environments, which creates yet another layer of hazards.”
And so Stoner said this new data will allow wildlife managers to map and better predict when and where deer will move next. Based on those predictions, solutions like temporary fencing could work to keep deer and predators away, leaving your lawn nicely manicured.