Elk are one of the most iconic animals in North America, easily recognizable by their large size, regal antlers, and distinct bugling calls. If you’ve ever wondered whether these majestic creatures feast on willow trees, you’re not alone.
Willows are a common sight across elk habitat, so it’s only natural to ask if elk browse these plants.
If you’re short on time, here’s a quick answer to your question: yes, elk do eat willow trees. Willow leaves and shoots are a nutritious part of the elk diet. But elk are generalist browsers that eat a wide variety of plants, not just willows.
An Overview of Elk Diet and Feeding Patterns
Elk are ruminants that eat a wide variety of plant matter
As ruminants, elk have a four-chambered stomach that allows them to digest fibrous plant material that many other animals cannot. Their diet consists primarily of grasses, sedges, forbs (herbaceous flowering plants), shrubs, and trees.
This varied plant diet provides them with carbohydrates, protein, fats, vitamins, and minerals. Some of the most common plants found in an elk’s diet include:
- Grasses – bluegrass, fescue, wheatgrass, bromegrass
- Sedges – elk sedge, beaked sedge
- Forbs – lupine, clover, vetch
- Shrubs – willow, aspen, mountain maple
- Trees – aspen, cottonwood, willow
Elk are generalist herbivores and will eat almost any vegetation available. They utilize different food sources based on the season and habitat. This diverse diet allows them to find adequate nutrition across various ecosystems and climates.
Elk feeding patterns change by season
Elk diets shift during the year as different food sources become available. In the spring, elk take advantage of sprouting grasses and flowering plants. Protein-rich new plant growth offers needed nutrition after the winter. Summer brings mature grasses, forbs, and shrubs.
As autumn approaches, elk move to higher elevations to feed on available plants before the first snowfall. In winter, elk rely heavily on woody shrubs and trees to survive when herbaceous plants are buried under snow. Conifers like pines and junipers provide vital winter forage.
Willow trees play an important role in elk diet, being consumed year-round but especially during winter. Elk browse willow bark and stems for the nutrients they provide. Aspen trees are another key food source. Elk eat aspen leaves in spring and summer and woody twigs in fall and winter.
Elk may also strip bark from trees such as aspen, pine and maple.
Supplemental feeding sites can be crucial when natural winter forage is limited. Ranchers provide hay and pelleted feeds to prevent starvation of elk herds and conflicts with livestock. With quality forage scarce in winter, elk gravitate toward these feeding sites in high numbers.
In areas of overpopulation, elk may cause detrimental overgrazing and overbrowsing of forests and rangelands. Understanding the seasonal shifts in elk diets helps land managers know which plant species are most vulnerable during different times of year.
Adjusting elk population numbers through hunting helps keep their feeding patterns in balance with the ecosystem.
Willow Species Eaten by Elk
Willows provide valuable nutrition for elk
Willow trees and shrubs make up an important part of an elk’s diet, especially in winter when other plant food becomes scarce. The bark, shoots, and leaves of willows contain nutrients like protein, calories, vitamins, and minerals that help sustain elk through the colder months (NPS).
Willows are a preferred winter food source because their bark and wood are high in digestible energy and protein compared to other woody plants. According to research, willows can provide up to 90% of an elk’s metabolic needs in winter in certain areas (Sachro et al. 2002).
This helps elk to conserve fat reserves and body protein when qualitity forage is limited.
In one study of elk wintering grounds in Wyoming, willow made up 73% of the elk diet from January to April when snow covered other vegetation (Wambolt 2001). This reliance on willow demonstrates how vital this tree is to sustaining elk through harsh winters in many parts of their range.
Preferred willow species include…
Elk consume several willow species, but they tend to prefer certain types first. According to research in Yellowstone National Park, Rocky Mountain willow (Salix monticola) and Geyer’s willow (Salix geyeriana) are among the most browsed willow species by elk (Yellowstone NP).
These willows grow rapidly and abundantly in montane regions, providing a reliable food source for elk. Their flexible stems and branches also make them more accessible for browsing ungulates compared to other trees and shrubs.
In lower elevations, such as foothills and valleys, elk also commonly browse sandbar willow (Salix exigua), shining willow (Salix lucida), and arctic willow (Salix arctica). The protein-rich and fast-growing leaves, shoots, and catkins of these species help sustain elk populations through harsh winters (Sachro et al.
2002).
| Willow Species | Region | Plant Parts Eaten |
|---|---|---|
| Rocky Mountain willow (Salix monticola) | Montane | Shoots, bark |
| Geyer’s willow (Salix geyeriana) | Montane | Leaves, shoots |
| Sandbar willow (Salix exigua) | Low elevations | Catkins, shoots |
Understanding which willow species elk prefer to browse in different regions and seasons can help guide habitat conservation efforts. Protecting these important food resources will help ensure the health and survival of elk herds for generations.
Why Elk Browse Willow Trees
Willows offer easily digestible nutrients
Willow trees and shrubs provide essential nutrients that are easy for elk digestive systems to process. The bark, shoots, and leaves contain high levels of protein, vitamins, and minerals like calcium and magnesium.
In particular, willow shoots in early spring are packed with nutrients and low in toxins, making them a perfect food source for elk emerging from the nutrient-poor winter months.
Compounds like tannins and phenols found in most trees can irritate elk digestive tracts. Fortunately, willows contain lower tannin levels than other trees like oak and maple. This means elk can consume willow foliage more freely without adverse effects.
Willow bark is high in calcium
Willow bark is an excellent natural source of calcium for elk. Calcium plays vital roles in bone growth and strength, muscle function, nerve signaling, and enzyme regulation. Ungulates like elk require high calcium intake to support antler growth and lactation.
According to research from the University of Alaska Fairbanks[1], willow stems can contain over 1% calcium per dry weight. This calcium density is on par with commercial livestock feeds. By gnawing and stripping willow bark, elk obtain plentiful bioavailable calcium to meet their high physiological demands.
Willow shoots are available year-round
While new willow shoots offer the highest nutritional quality, elk also browse older willow stems and bark year-round. Willow species thrive across different elevation zones and soil moisture levels. So even when preferred foods become scarce, willow thickets reliably provide easily accessible forage.
During summer, elk take advantage of rapidly growing shoots and leaves. In winter, twigs and bark soaked in nutrients from the previous growing season provide energy reserves. And nutritious first shoots emerge early while snow still covers the ground.
This wide temporal availability accounts for up to one-third of elk diets by some estimates.
Other Key Plants in the Elk Diet
Grasses
Grasses make up a large portion of an elk’s diet, especially in the summer months. Some common grass species that elk feed on include bluebunch wheatgrass, Idaho fescue, and western wheatgrass. Grass allows elk to build up fat reserves to get them through the winter.
According to research by the Rocky Mountain Elk Foundation, grasses can comprise up to 90% of an elk’s summer diet.
Forbs
Forbs, also known as broadleaf herbaceous plants, are another key part of an elk’s diet. Some common forbs that elk feed on include lupine, wild parsley, clover, and fringed sagebrush. Forbs provide essential nutrients for elk including protein, minerals, and fiber.
Studies have shown that elk calf survival and pregnancy rates increase in areas with abundant forb growth. Forbs can make up 20-40% of an elk’s annual diet according to wildlife biologists.
Woody Browse
In the winter, when grasses and forbs become scarce, elk rely more heavily on woody browse to survive. This includes the leaves, twigs, and shoots of shrubs and trees. Some favorite woody browse plants for elk include mountain mahogany, serviceberry, chokecherry, snowbrush, and yes, even willow trees.
Browsing on woody vegetation helps sustain elk through the tough winter but is harder to digest. Biologists estimate that woody browse provides 50-80% of an elk’s winter nutrition.
When and Where Elk Feed on Willows
Willow Use Peaks in Winter and Early Spring
Elk rely heavily on willow as a food source during the winter and early spring months when other vegetation is scarce. Browsing on willow makes up 60-90% of an elk’s diet from late fall through early spring.[1] This peak in willow consumption coincides with the harshest weather conditions when elk need more energy to stay warm and find food under the snow.
Willows retain their nutritional value better than grasses and other herbaceous plants in winter. The shoots and stems remain upright above the snowpack, providing vital calories and nutrients when elk struggle to paw through the snow to uncover grass and other foods.
In addition, willow bark and wood contain compounds like salicin that may have medicinal benefits to elk.
In early spring, when elk mothers are nursing newborn calves, willow continues to offer easy access to highly digestible nutrients. Nursing mothers will eat 30-50% more food during the calving season. Abundant willow in riparian areas provides a perfect protein-rich food source.
Riparian Areas Provide Abundant Willow Growth
Elk browse on a variety of willow species like Geyer’s willow, yellow willow, and arctic willow, but they prefer to feed in riparian areas along rivers and streams where willow thrives. The moist soil conditions in riparian zones combined with annual floods provide ideal habitat for willow communities.[2]
In western mountain regions, over half of elk browsing activity occurs within 330 feet of streamside habitats. Herds will migrate down from higher elevations in fall to reach these willow-rich riparian zones before the snow falls.
Concentrated browsing pressure on willow can be up to 28 times higher in riparian areas compared to upland sites.[3]
Riparian willows provide cover as well as forage. Mature willow stands form dense thickets along stream banks that shelter elk from weather and predators. In more open landscapes, even small linear riparian corridors become oases of food and security for elk.
Conclusion
In summary, elk certainly do eat parts of willow trees, especially willow leaves, shoots, and bark. However, willows make up just one component of the diverse elk diet. As browsing ruminants, elk rely on a variety of nutritious native plants to meet their nutritional needs through the seasons.
By understanding which plants elk eat and when they eat them, we can better manage habitat to support thriving elk herds.
