The Snowshoe Hare (Lepus americanus) is a medium-sized lagomorph inhabiting the dense boreal and coniferous forests of North America. Found across a broad range that includes the Rocky Mountains and the Appalachian uplands, its survival hinges on an extremely flexible diet. This diet is reconfigured by the contrast between the abundance of summer and the scarcity of winter. Seasonal shifts in food availability dictate what the hare consumes and how it extracts nutrition from its forage.
Seasonal Variations in Summer
The warmer months provide the Snowshoe Hare with a rich and diverse menu of vegetation. Hares browse extensively on a variety of herbaceous plants, which are characterized by high water content and easily digestible nutrients. This summer diet includes succulent items like green grasses, various clovers, and the leaves of young deciduous shrubs.
Forages also include ferns, the new growth of woody plants, and small berries. The abundance of this tender, low-fiber material allows the hare to maximize its intake of protein and energy during its peak reproductive and growth season. Consuming these fresh plants also contributes to the hare’s hydration.
Survival Strategies in Winter
The onset of cold weather and deep snow necessitates a shift in the hare’s diet. When soft ground cover is no longer accessible, the Snowshoe Hare turns its attention to woody browse. This winter fare consists almost entirely of low-quality, high-fiber material, such as the buds, twigs, and bark of various trees and shrubs.
Preferred species for browsing include willow, trembling aspen, birch, and the needles of certain evergreens. The deep snowpack, which appears to be a hindrance, actually assists the hares by raising the ground level. This allows them to reach and clip branches and buds that would otherwise be too high. This tough, lignified diet provides significantly less usable energy than summer forage, forcing the hare to consume larger volumes to maintain its body temperature and condition.
Specialized Nutritional Adaptations
Surviving on a diet that includes highly fibrous woody material requires a specialized digestive process unique to lagomorphs. Hares employ coprophagy, a biological mechanism involving the re-ingestion of soft fecal pellets called cecotropes.
After initial digestion, undigested plant fiber is diverted to the cecum, a large pouch where symbiotic bacteria reside. These microorganisms break down the remaining cellulose and synthesize B vitamins and protein that the hare’s system could not absorb the first time through.
The resulting cecotropes, rich in these salvaged nutrients, are then excreted and immediately consumed by the hare directly from the anus. This second pass through the digestive system ensures the maximum extraction of protein and vitamins, which is crucial for survival on a nutrient-poor winter diet.
The Hare’s Role in the Forest Food Web
The feeding habits of the Snowshoe Hare influence the structure of the surrounding forest ecosystem. Their constant browsing creates distinct horizontal lines on shrubs and saplings, known as “browse lines” or “hare lines,” which visibly shape the local plant community. The hares’ consumption of specific plant species also affects the forest’s regeneration patterns, favoring the growth of less palatable vegetation.
The availability of the Snowshoe Hare’s food sources drives the 8- to 11-year predator-prey cycle in the boreal forest. When hares are numerous due to abundant food, their primary predator, the Canadian Lynx, experiences a corresponding population boom. Conversely, the scarcity of winter forage can contribute to a hare population crash, which is quickly followed by a decline in the lynx population. This demonstrates that the hare’s diet and population dynamics regulate the entire food web.