The coyote (Canis latrans) is a highly adaptable predator found throughout Yellowstone National Park. This canine’s dietary flexibility allows it to thrive in environments ranging from open valleys and sagebrush grasslands to higher-elevation forests. Yellowstone coyotes are among the largest in the United States, typically weighing around 30 pounds, which aids in their capacity to hunt and scavenge.
The Primary Diet: Small Mammals and Rodents
The most consistent and reliable food source for coyotes in Yellowstone is small mammals and rodents. Voles (Microtus spp.) are the principal small mammal consumed, often making up a significant portion of the coyote’s food intake throughout the year. These small prey are supplemented by mice, pocket gophers (Thomomys talpoides), and Uinta ground squirrels (Spermophilus armatus) during the warmer months when they are active above ground.
Coyotes employ a distinctive hunting strategy to capture these elusive rodents, often referred to as “mousing.” They use their keen sense of hearing to pinpoint the exact location of a small mammal moving beneath the snow or vegetation. Once the target is located, the coyote executes a characteristic, high-arcing pounce, driving its front paws down to pin or stun the prey. Studies have shown that coyotes are quite successful in these attempts, with researchers observing a success rate of about 35% in small mammal predation attempts.
The effectiveness of this small-prey hunting is influenced by environmental conditions, particularly snow depth. Low snow cover can increase the rate at which coyotes detect and capture rodents compared to bare ground, likely by providing a better acoustic environment for locating prey. However, as snow depth increases significantly, the coyotes’ hunting success declines, forcing them to modify their foraging behavior.
Seasonal Variation and Scavenging
The winter months introduce a period of resource scarcity, making scavenging a necessary component of survival. During this time, coyotes frequently rely on the carrion of large ungulates, such as elk, bison, and moose, that have succumbed to cold, starvation, or disease.
Carrion provides a crucial energy subsidy during the deep snow periods, allowing coyotes to conserve energy otherwise spent on hunting. While scavenging is the main way they interact with large animals, coyotes will occasionally prey on vulnerable young ungulates, such as newborn elk calves or mule deer fawns, shortly after birth in the spring. Predation on healthy adult ungulates is rare, typically occurring only during severe winter conditions when the prey is weakened, and often involves cooperative hunting by a pack of coyotes.
In the summer and fall, coyotes broaden their omnivorous intake to include insects, especially grasshoppers, as well as fruits and berries. During these warmer periods, they exploit temporary food surpluses.
Dietary Shifts Due to Wolf Presence
The reintroduction of gray wolves to Yellowstone in the mid-1990s profoundly altered the coyote’s foraging landscape. Before the wolves returned, coyotes partially filled the niche of a large predator. The re-establishment of wolves introduced a dominant competitor that directly affects the coyote’s access to large-animal carrion.
Wolves are highly effective at defending their kills, often excluding coyotes from feeding on fresh ungulate carcasses. This competition forced coyotes to rely more heavily on their small mammal diet, effectively pushing them back into the role of a mesopredator. The presence of wolves also led to a reduction in coyote density in certain areas of the park, as the larger canids frequently kill coyotes to minimize competition for resources.
The continuous supply of wolf-killed ungulates has created a year-round source of carrion for surviving coyotes. Coyotes have adapted by exhibiting increased vigilance and feeding quickly on carcasses, often waiting until the wolves have moved away. This trade-off provides an energy-rich food source, but it comes with the heightened cost of increased risk.