The moose (Alces alces) is the largest member of the deer family, a massive herbivore whose immense body places significant demands on its diet. Weighing over a thousand pounds, an adult moose requires a constant supply of energy to maintain its bulk and power through harsh northern environments. This enormous size necessitates consuming a vast quantity of plant matter, with an average adult needing to meet a daily energy requirement of roughly 9,770 to 23,000 kilocalories.
Seasonal Food Sources
The moose’s diet undergoes a dramatic shift across the year, directly correlating with the nutritional quality and availability of vegetation in the boreal forest. Summer is a period of intense feeding, where the animal must build up fat reserves to prepare for the long winter scarcity. This summer diet is high-volume and high-nutrition, focusing on easily digestible plant parts.
Moose consume vast amounts of succulent leaves, tender shoots, and forbs from deciduous trees and shrubs during the growing season. Preferred summer browse includes the foliage of birch, willow, and aspen, which offers a high concentration of nutrients for rapid weight gain. This caloric surplus is necessary for cows to support lactation and for bulls to regrow their massive antlers.
Winter presents a severe challenge as plants enter dormancy and snow covers the landscape, forcing the moose to switch to a low-volume, low-nutrition survival diet. Their food source shifts almost entirely to woody browse, consisting of the twigs, stems, and bark of various trees. They strip bark from trees like aspen, birch, and willow, and consume the evergreen twigs of balsam fir and spruce.
This coarse winter forage, while abundant, provides far fewer calories and is much more difficult to digest than the summer greenery. Moose must rely on their accumulated fat reserves to offset this energy deficit, which often results in a loss of up to 20% of their body weight by springtime. Their long legs allow them to reach higher branches for more tender tips, giving them an advantage over smaller herbivores when snow is deep.
The Importance of Sodium and Aquatic Plants
A unique physiological need drives a specific component of the moose’s summer diet: the requirement for sodium. Terrestrial vegetation is generally deficient in this mineral, which is necessary for nerve and muscle function. This deficiency motivates significant foraging behavior in warmer months.
Moose seek out aquatic plants to fulfill this mineral requirement because submerged vegetation often contains sodium levels far higher than those found in woody browse. Species like pondweed, water lilies, and water shield are particularly favored for their high sodium content. This explains why moose are frequently seen wading in shallow ponds and lakes during the summer.
To reach the most sodium-rich parts of the plant, moose often submerge their heads completely. They are even known to dive fully underwater, going down as far as 20 feet to graze on plants rooted at the bottom. The moose is adapted for this behavior, possessing a specialized snout that allows them to close their nostrils and continue feeding while submerged.
Quantity and Browsing Technique
The sheer quantity of food a moose consumes is directly proportional to its massive size, requiring constant foraging during the growing season. An adult moose needs to consume approximately 40 to 70 pounds of vegetation per day throughout the spring and summer. This high intake is managed by a specialized digestive system.
The moose is a ruminant, meaning it possesses a four-chambered stomach, similar to cattle and sheep. This complex system allows them to ferment and efficiently extract nutrients from the fibrous plant matter they consume. Food is partially chewed, swallowed into the first two stomach compartments (the rumen and reticulum), then regurgitated as cud for a second, more thorough chewing process called rumination.
Moose are classified as “concentrate selectors” or “browsers,” meaning they preferentially select nutrient-dense leaves, forbs, and tender shoots over grass. They use their long, prehensile lips and flexible tongue to strip leaves and twigs from branches, rather than grazing like cattle. This highly selective browsing technique allows them to target the most nutritious parts of a plant, which is important given the immense volume of food they must process daily.