Unlocking the needs and habits of our mule deer

mule deer | Saddle Rock

(Photo provided/Susan Ballinger) Mule deer travel on Saddle Rock in mid-March.

Sagebrush buttercups | Jacobson Preserve

(Photo provided)
Sagebrush buttercups have popped up on the Jacobson Preserve.

The foothills are softly greening up, bright yellow buttercups are in bloom, and male western meadowlarks sing loudly from atop sagebrush.

From our human perspective, the harsh conditions of winter are over, and foothills trails are calling our names.

Yet in our foothills, native mule deer are still experiencing a time of continued food scarcity, after a long winter of foraging on leafless bitterbrush branches and evergreen sagebrush leaves. It is critical for mule deer to continue conserving energy after the long winter, until high-quality, nutritious food is available in the new leaves on spring grasses, wildflowers and shrubs.

It isn’t until late April that the profusion of leafing out, easy-to-digest, protein-rich shrubs like bitterbrush, serviceberry and chokecherry launch the time of food abundance for deer. The North Wenatchee Foothills trail closures until April 1 are specifically designed to help mule deer conserve energy by providing a buffer zone between people, leashed dogs and deer during the final weeks of food shortage.

Mule deer are browsers that eat the soft leaves and branch tips of more than 40 kinds of deciduous and evergreen shrubs, trees, grasses and wildflowers. In Chelan County, they follow a semi-annual elevational food-seeking migration, up into the mountains for summer, and down to the foothills and valleys for winter, traveling 40-50 miles each way. They widely disperse throughout the mountains during summer, feeding and storing up fat reserves.

Mule deer have specific winter-range habitat needs. Fall snowfall in the mountains triggers migration to lower valleys that have less snow depth so native shrubs, like bitterbrush and sagebrush, are available as food. A typical mule deer needs 1.5 gallons of water per day, so daily access to rivers or creeks is essential.

They require stands of shrubs and trees for thermal cover, to moderate temperature extremes and provide protection from wind. They need hiding cover to help avoid predators like cougar, coyote, bobcat and golden eagle. Because these predators typically avoid human contact, mule deer often select habitat in close proximity to settlement as an avoidance strategy. They rest during the day to conserve energy, and feed in the early morning and late evening. They escape predators by “stotting,” leaping in high bounds in a zigzag pattern to reach protective cover, using up precious energy reserves.

As a long winter progresses and fat reserves are exhausted, food scarcity increases as constant nutritional demands (especially for pregnant females) results in mule deer being weak and vulnerable in early spring. Conserving energy is key, so any calories used to flee in order to avoid perceived predators — like hiking people, leashed dogs or free-running dogs — can push a deer closer to starvation, or make them more susceptible to disease or parasites, like ticks.

As has happened in the Wenatchee area over the past 50 years, traditional mule deer wintering grounds have been converted to human settlement. Mule deer populations have decreased since 1940 throughout the western U.S. Concurrently, year-round human recreation has increased in mule deer habitat. Current research seeks to quantify deer perceived predator-fleeing response to recreational disturbance by hikers, cross-country skiers and dog walkers. Practically, when you (and your leashed dog) are using the foothills trails, keep your distance from daytime resting mule deer. You’ve gotten too close if the mule deer change their behavior or flee.

Our homes, businesses and orchards fill the bottomlands and have replaced the original native plant communities formerly used as mule deer winter habitat, yet they still migrate to our valley bottoms. A state online publication has a fact sheet designed to help homeowners minimize wildlife conflicts (wdfw.wa.gov/living/deer.html). It lists practical options for protecting landscaping from deer including types of barrier fences, netting barriers and a homemade deer repellant spray. It includes a long list of deer-proof lan dscaping plants that can help you make purchasing decisions this spring. As homeowners, it is frustrating to find tulips and ornamental shrubs consumed, but it helps to realize that we’ve displaced the original mule deer locals.

Susan Ballinger is partnering with Wenatchee Valley College Continuing Education and the Wenatchee River Institute to offer the Wenatchee Naturalist Course, beginning April 9. Learn more at www.wvc.edu.

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