Oregon State Study: Skunks Move More Efficiently Than Deer, Weather Influences Patterns

A study in the Cascade Range in Oregon of a tiny, elusive skunk found the animal can cover more ground than deer and is sensitive to climate change, particularly severe winter weather.

The research is important because small mammals such as the western spotted skunk face major threats from human-induced land use change, said Marie Tosa, who as an Oregon State University graduate student spent 2½ years studying the skunks. Her findings(Link is external) provide data to shape future skunk monitoring efforts and identify threats they face.

The western spotted skunk, which typically weighs 1 to 2 pounds and is about the size of a squirrel, is smaller than the striped skunk that is common in urban environments.

“The easiest way to describe them is a tube sock,” said Tosa, who is now a postdoctoral researcher at Oregon State. “They’re a black and white tube sock. They are mostly black but they have white spots all over them. They have this giant white spot on their forehead. And they’re really, really adorable.”

The western spotted skunk prefers more undisturbed habitat, such as mountainous areas, and is nocturnal, so it is rarely seen. Yet it lives in areas from New Mexico to British Columbia and California to Colorado

“For such an abundant carnivore in these forests, we don’t really know anything about them,” said Taal Levi, an associate professor at Oregon State’s College of Agricultural Sciences and advisor to Tosa. “This project was trying to figure out more about them: trying to learn about their natural history; what they do in these forests; what do they need; how do they influence the ecosystem that they are in.”

Tosa, Levi and Damon Lesmeister of the U.S. Forest Service’s Pacific Northwest Research Station in Corvallis studied the western spotted skunk in part because of what happened to the eastern spotted skunk, which lives in the central and southeastern United States.

The population of that species declined about 90% between 1940 and 1950 and by 99% by 1980. It is now listed as vulnerable by the International Union for Conservation of Nature and was considered for listing under the Endangered Species Act.

“Habitat loss is believed to be a factor in the population decline, but the reasons are not well understood because the species was not well studied prior to or during the decline,” said Lesmeister, who conducted research on the eastern spotted skunk in the 2000s.

Tosa conducted her research from 2017 to 2019 in the H.G. Andrews Experimental Forest, a nearly 16,000-acre research forest about an hour east of Eugene. The landscape is steep, with hills and deep valleys and elevation ranges from 1,350 to 5,340 feet.

That landscape made finding and tracking skunks difficult. Tosa started by setting trail cameras with sardines and cat food as bait to lure the skunks. Camera images gave her a general sense of where the skunks were and informed where she placed box traps, which she also baited and camouflaged with burlap, moss and bark.

She then spent hundreds of days driving thousands of miles to check more than 100 cameras and 50 to 100 traps.

When she found a skunk in a trap, she would carefully open it up, secure the animal, tranquilize it to temporarily sedate it and place a radio collar on it. This inevitably led to being sprayed. She estimates she was sprayed 50 to 100 times.

She said the spray smells like really strong raw garlic. Her method to remove the smell? A paste of hydrogen peroxide, Dawn dish soap and baking soda.

Once collared, she could use radio telemetry day and night to locate and track the skunks’ movement.

With that data, she determined that the skunks have a home range up to 12 square miles. That far exceeds similar size mammals and even deer, which have a home range of less than one-half of a square mile. She thinks the skunks are covering so much ground because of limited food resources.

Other findings included:

• The skunks appear to like old growth forests and younger forests. The younger forests are likely appealing because they contain more food, such as berries and small mammals.
• Skunks are vulnerable to winter weather, particularly cold temperatures and accumulated snow. This was particularly evident during a heavy snow event in February 2019.
• Skunks were distributed across 63% of the study area with highly overlapping home ranges, indicating a lack of territoriality.

Tosa’s field research concluded before three wildfires burned in the forest during the past four years. She speculated that the skunks are likely well adapted to fire and is interested in conducting a post-fire study of the skunks.

The research findings were recently published in Ecosphere.