Elk (\(Cervus\) \(canadensis\)) are the second-largest species of deer in the world, distributed across North America in diverse ecosystems from mountain forests to open grasslands. As large herbivores, their diet drives their health and reproductive success, making it important for wildlife conservation and habitat management. Understanding what plants elk consume provides insight into their ecological role and the nutritional demands that shape their behavior. The composition of an elk’s diet reflects the vegetation available in their environment, dictating their ability to survive.
Primary Categories of Elk Forage
The elk diet is categorized into three main types of vegetation: graminoids, forbs, and woody browse. Elk are classified as intermediate or mixed feeders, meaning they adapt their consumption based on what food is most available and nutritionally rich. However, they function primarily as grazers, meaning grasses and grass-like plants are the most substantial component of their yearly intake.
Graminoids include true grasses, sedges, and rushes, and these often form the bulk of an elk’s diet, especially in expansive open meadows. Preferred species include native varieties such as Idaho fescue, bluebunch wheatgrass, and rough fescue, which are sought after for their palatability. Even dried, cured grasses can make up a significant portion of the diet, particularly when other forage is scarce.
Forbs are non-woody, broad-leafed flowering plants that represent a high-quality food source for elk. While they may not constitute the largest volume of the diet year-round, they are selectively targeted for their high protein and nutrient content. Specific forbs consumed include:
- Dandelion
- Clover
- Geranium
- Aster
These are often heavily utilized during the summer months.
The third category is browse, which consists of the leaves, twigs, and bark of woody shrubs and trees. While elk are not primarily browsers like deer, they will consume species such as:
- Willow
- Mountain mahogany
- Aspen
- Chokecherry
Browse is considered a maintenance food, becoming more important when snow cover makes ground forage inaccessible or during transitional periods.
Seasonal Changes in Foraging
An elk’s diet changes dramatically in response to the seasons, driven by vegetation availability and nutritional requirements. The highest nutritional demands occur during the spring and summer, when females are lactating and all elk are recovering body condition and growing antlers. During this time, they prioritize forage with high levels of digestible energy and protein, often following the “green-up” of new growth to maximize intake.
In the spring, elk seek out the first emerging, highly succulent grasses and early forbs, which are particularly nutrient-dense. As summer progresses, the diet often shifts to a higher proportion of forbs, which can constitute 60 to 100 percent of their daily intake where these plants are abundant. This high-energy consumption is necessary for building the body fat reserves needed to survive the winter.
The autumn transition sees plants maturing and drying out, leading to a decline in forage quality and a shift back toward lower-quality grasses and woody browse. Certain plants, such as prairie sagewort, can offer a temporary boost of calorie-dense sugar following the first frost, which elk exploit to increase fat storage before the rut. In winter, the diet becomes one of necessity, relying on dried grasses pawed through the snow or the woody stems and bark of browse species like willow and aspen. Food availability during this period is the primary factor limiting the size and health of elk populations.
Environmental Impact of Elk Feeding
The distinct feeding behaviors of elk, particularly grazing and browsing, have measurable consequences for the ecosystems they inhabit. Grazing, the consumption of grasses and forbs, can sometimes benefit grassland health, as the removal of above-ground biomass can stimulate increased grass growth. This effect is pronounced in heavily grazed areas and during drier years.
The browsing component of their diet, when carried out by large, concentrated populations, can significantly alter plant community structure. High-density foraging pressure can severely reduce the size, biomass, and frequency of preferred shrub and tree species. Intense browsing can inhibit the regeneration of woody species like willow and aspen, which are highly palatable.
This sustained herbivory can lead to a net loss of nitrogen from woody plant communities, reducing the productivity and growth rates of the remaining plants. The long-term consequence of heavy browsing is a shift in plant community composition, reducing biodiversity and potentially hindering forest regeneration efforts. Managing elk populations is therefore a component of maintaining the health and structure of forest and rangeland habitats.