Moose are strictly herbivorous, meaning their diet is composed entirely of plants, and they do not naturally consume meat. The idea of a moose eating flesh is largely a misconception, stemming from rare behaviors driven by nutritional deficiencies rather than true carnivory. Their entire biology, from their teeth to their stomach, is specialized to process tough, fibrous plant matter.
Primary Diet: Browsing and Herbivory
Moose are classified as browsers, distinguishing them from grazers like cattle. Their diet consists of the leaves, tender shoots, and twigs of woody plants, such as willow, birch, and aspen. This forage makes up the bulk of their food intake, especially during the winter when they rely on fibrous, lower-quality parts of trees and shrubs.
The summer months bring a transition to eating more succulent leaves, forbs, and substantial aquatic vegetation. Aquatic plants, such as pondweed and water lilies, are important because they are a rich source of sodium, a mineral scarce in most terrestrial plants. Moose can dive over 18 feet to reach these submerged plants, acquiring sufficient sodium for the entire year.
Digestive System Built for Plants
The anatomy of a moose is optimized for a plant-based diet, starting with its dental structure. Unlike carnivores, moose lack upper incisor teeth, possessing a hard dental pad against which the lower incisors shear vegetation. Their cheek teeth are short and narrow, designed for crushing and puncturing plant material to release nutrients.
Moose are ruminants, possessing a four-chambered stomach system that facilitates the breakdown of cellulose. The first and largest chamber, the rumen, acts as a fermentation vat, housing specialized bacteria and microorganisms. These microbes produce the enzyme cellulase, which breaks down the tough cellulose found in plant cell walls—a process impossible for the moose’s own enzymes.
The partially digested food, or cud, is periodically regurgitated and re-chewed for further mechanical breakdown before passing through the other three stomach chambers. This complex digestive process is dedicated to extracting energy from fibrous plants. A carnivore’s simple, acidic stomach is built to rapidly break down protein and fat, not to ferment cellulose.
Addressing Instances of Non-Plant Consumption
The occasional consumption of non-plant material by moose is known as opportunistic mineral seeking, not true predation. Instances of moose chewing on items like shed antlers or animal bones, a behavior called osteophagia, are driven by a severe deficit of minerals, most often calcium and phosphorus. This behavior is a form of mineral supplementation to address a dietary shortfall.
This non-plant consumption is fundamentally different from a carnivorous diet because the moose’s digestive system cannot efficiently process and absorb the proteins and fats in the bone or flesh. Moose are known to frequent natural salt licks or road salt deposits to satisfy their strong physiological need for sodium, especially in the spring. While they may accidentally ingest insects or small organisms while browsing, these minute amounts do not constitute a meaningful part of their overall nutrition or change their classification as herbivores.