The Golden Eagle, Aquila chrysaetos, is one of the largest and most widely distributed raptors in the Northern Hemisphere, inhabiting open country across North America, Europe, and Asia. This formidable bird of prey is characterized by its powerful build, immense wingspan, and dark brown plumage accented by lustrous golden feathers on the nape of its neck. As an apex predator, the Golden Eagle plays a significant role in its ecosystem, relying on a diverse but focused diet to sustain its large size and impressive hunting prowess.
Primary Prey: Mammals as the Mainstay
The Golden Eagle’s diet is heavily skewed toward medium-sized mammals, which provide the necessary high caloric intake. Across North America, studies indicate that mammalian prey constitutes nearly 84% of the eagle’s diet by the number of individuals consumed. The most significant prey group is lagomorphs, including various species of hares and rabbits, often comprising over 50% of the eagle’s meals. Black-tailed jackrabbits are a key food source, especially in the arid grasslands of the western United States and Mexico.
Sciurids, including ground squirrels, prairie dogs, and marmots, form another substantial portion of the regular diet. California ground squirrels and yellow-bellied marmots are frequently targeted where they are locally abundant. Capturing these medium-sized rodents and lagomorphs efficiently meets the eagle’s daily energy demand, as preferred prey weight generally falls between 1.1 and 8.8 pounds.
While smaller prey dominates, Golden Eagles are capable of taking larger animals, usually by targeting vulnerable individuals. They occasionally prey on the young of small ungulates, such as deer fawns or mountain goat kids. These larger items are typically newborn, weighing close to the eagle’s transportable limit (4 to 11 pounds). The strategy often involves a “low flight with sustained grip attack” to subdue the prey.
Secondary and Opportunistic Food Sources
When primary mammalian prey is scarce, the raptor incorporates diverse secondary food sources. Birds are the second-most frequent prey group, making up around 15 to 20% of the diet in North America. Common avian targets include gallinaceous birds like grouse and partridge, but eagles will also opportunistically hunt waterfowl, gulls, and smaller raptors.
The eagle also preys on reptiles, with snakes and tortoises occasionally appearing in the diet. This reptilian consumption is generally minor in terms of overall biomass. Fish and insects are the least significant components of the diet, rarely making up more than a fraction of the total caloric intake.
Scavenging for carrion is a significant component of the Golden Eagle’s diet, especially during winter. When primary prey is scarce or hidden beneath snow, eagles readily feed on carcasses of animals like deer or sheep. This opportunistic behavior is most noticeable in areas with harsh winters, allowing eagles to conserve energy rather than expending effort on difficult hunts.
Hunting Strategies and Techniques
The Golden Eagle employs several sophisticated hunting strategies utilizing its phenomenal eyesight and speed to secure prey in open landscapes. The species possesses vision estimated to be four to eight times more acute than a human’s, allowing it to spot small rodents from great distances while soaring. The most dramatic hunting method is the “stoop,” a steep, high-speed dive toward the prey with wings pulled close to the body.
During a stoop, the eagle can reach speeds between 150 to 200 miles per hour, maximizing the force of impact to instantly incapacitate its target. For running prey, the eagle often executes a diagonal approach, but for stationary targets, the dive may be nearly vertical for a quick, decisive strike. The eagle’s powerful talons, which can exert immense pressure, are the primary tool for securing and killing prey upon impact.
Eagles frequently use high vantage points, such as cliffs, rocky outcrops, or power poles, for a technique known as perch hunting. From these elevated positions, the raptor can survey the surrounding terrain for extended periods, conserving energy until a prey animal is detected. Another specialized technique is “contour hunting,” where the eagle flies low along the contours of a hill or ridge, using the terrain as cover to surprise prey before launching the final attack.
Cooperative hunting is a specialized strategy occasionally employed by mated pairs to capture larger or faster animals like foxes or coyotes. In this coordinated effort, one eagle will distract or flush the prey, chasing it toward the second eagle lying in ambush. This teamwork significantly increases the likelihood of a successful capture for prey that would otherwise be too difficult for a single bird to tackle.
Geographic and Seasonal Diet Variation
The specific composition of the Golden Eagle’s diet varies significantly based on its geographic location and the seasonal availability of local fauna. In the grasslands and deserts of the western United States, the diet is overwhelmingly dominated by lagomorphs and ground squirrels due to their abundance. Conversely, in parts of Scandinavia and Scotland, the diet shifts to include a higher proportion of birds, with grouse and other avian species sometimes becoming the primary food source.
Coastal or island populations may rely more heavily on fish, seabirds, and their nestlings, adapting their foraging strategies to the local environment. For example, studies in the Channel Islands found that eagles preyed on feral piglets and deer fawns, reflecting the specific availability of those non-native species. This geographic plasticity ensures the eagle remains an effective predator across a vast range of habitats.
Seasonal changes drive important shifts in foraging behavior. During the spring breeding season, increased energetic needs lead eagles to target the young of various species. The consumption of fledglings and nestlings provides an easy, concentrated food source for feeding growing chicks. In contrast, the cold winter months see eagles relying heavily on carrion, such as deer and elk, to maintain energy balance when live prey is difficult to locate beneath snow.