Moose, the largest members of the deer family, are an iconic species within Yellowstone National Park. These large ungulates browse on vegetation, influencing plant communities and contributing to the park’s biodiversity.
Yellowstone’s Moose Count
Estimating the exact number of moose in Yellowstone National Park presents challenges due to their elusive nature and the vast, rugged terrain. The moose population has seen a notable decline from approximately 1,000 individuals in the 1970s to fewer than 200 today. A 2013-2015 study estimated between 150 and 186 moose occupied northern Yellowstone.
Influences on Moose Numbers
Several biological and environmental factors significantly influence the moose population within Yellowstone. Predation by animals such as wolves and grizzly bears affects moose numbers, though low food availability is considered a primary driver of long-term population decline. Habitat changes also play a substantial role, particularly the impact of the 1988 fires which destroyed large stands of spruce that served as winter forage for moose. This loss of food, combined with harsh winters, severely impacted the moose population. Competition for food resources with other large herbivores, such as elk and bison, also limits the availability of willow browse for moose. Disease also contributes to population dynamics. Winter tick infestations can weaken moose, and chronic wasting disease (CWD), a fatal neurological condition affecting deer, elk, and moose, has been detected in Yellowstone’s mule deer population, though its long-term effect on park moose is still being assessed. Climate impacts, including warmer temperatures and reduced snowpack, can also affect moose by influencing foraging conditions and increasing instances of extreme fire events that further reduce their habitat.
Where Moose Live in Yellowstone
Moose in Yellowstone National Park prefer specific habitats that provide both food and cover. They are frequently found in willow-lined stream corridors and other riparian areas, where they browse on woody vegetation. These long-legged animals are well-adapted to moving through water and deep snow, which allows them to access food sources in wetlands. Moose also utilize high-elevation forests, particularly mature stands of subalpine fir and Douglas-fir, for winter shelter and forage. Their distribution across the park is not uniform, with common sighting areas including the southwestern corner along the Bechler and Falls rivers, the riparian zones around Yellowstone Lake, and the Soda Butte Creek, Pelican Creek, Lewis River, and Gallatin River drainages. During winter, the northern range, especially between the Lamar River and Soda Butte Creek, and the northeast entrance, offers suitable habitat with spruce-fir forests and willow openings.
Tracking Moose Populations
Scientists and park officials employ various methods to monitor and estimate moose populations in Yellowstone. Non-invasive techniques, such as collecting fecal pellets, allow researchers to extract DNA for genetic analysis, estimating population size, vital statistics, individual identity, gender, and pregnancy status. Aerial surveys of willow habitats in spring show promise for tracking trends, though accurate counts remain challenging due to the animals’ solitary nature and ability to move undetected through dense forests. Ground observations and horseback surveys have also been used to track moose abundance.