Moose (Alces alces) are residents of Yellowstone National Park and are the largest member of the deer family found within the park’s boundaries. The specific subspecies inhabiting the area is the Shiras moose (Alces alces shirasi), which is generally the smallest of the four North American subspecies. Mature bulls often weigh over 1,000 pounds and stand tall on long, adapted legs that help them navigate their habitat.
Current Population Status
Moose are present in Yellowstone but are significantly less common than more numerous ungulates like elk and bison. The population has declined over the last few decades, with estimates suggesting fewer than 200 individuals, a substantial drop from the approximately 1,000 reported in the 1970s. This low number makes them one of the more challenging large mammals to spot within the park.
Accurately counting the population is difficult due to their solitary behavior and preferred dense, heavily vegetated terrain. A study in the northern range estimated between 150 and 186 moose occupied that area between 2013 and 2015. Population health has been challenged by factors such as the 1988 fires, which destroyed mature forest wintering habitat, and competition for willow browse from other ungulates.
Preferred Habitats and Geographic Range
Moose occupy specific ecological niches, contrasting with the open grasslands favored by grazers like elk. They seek out marshy areas of meadows, lake shores, and river corridors, where moisture supports their primary food sources. Their long legs allow them to move easily through deep snow and wade into waterlogged areas.
The most suitable habitat is along the park’s southern and western edges, connecting with Grand Teton National Park, which supports a larger population. Visitors have the best chance of viewing them in areas with extensive riparian zones. These locations include:
- The Bechler and Falls rivers in the park’s southwestern corner.
- Riparian zones around Yellowstone Lake.
- Soda Butte Creek and Gallatin river drainages.
- The Tower-Roosevelt area and Pebble Creek.
Unique Dietary Requirements and Behavior
Moose are classified as browsers, meaning their diet consists mainly of leaves, twigs, and shrubs, distinguishing them from grazers. Their specialized diet includes significant amounts of woody browse, particularly willow. In the summer, aquatic vegetation rich in sodium, such as pond lilies and duckweed, becomes a highly sought-after food source.
Consuming aquatic plants often requires them to wade into streams and ponds, a behavior that also helps them cool down during warmer months. During the deep-snow winter, their diet shifts dramatically, relying heavily on mature stands of subalpine fir and Douglas-fir. This dependence on specific trees means that habitat changes can significantly impact their survival rate.
Moose are typically solitary animals, often seen alone or in small family groups, unlike the large herds of bison or elk. This reclusive nature contributes to their lower visibility within the park. Although they may appear sluggish, they can be unpredictable and are fiercely protective of their young, especially cows defending their calves.