The bald eagle, North America’s iconic bird of prey, is classified as an opportunistic carnivore. Its diet is remarkably diverse, allowing it to thrive across various habitats near large bodies of water throughout the continent. The eagle is not restricted to a single food source, consuming a wide variety of prey and non-prey items based on availability. Its feeding habits reflect a highly pragmatic approach to survival.
The Dominance of Fish in the Diet
Fish form the centerpiece of the bald eagle’s diet, often making up between 60% and 90% of its total food intake, depending on location. The eagle’s close association with rivers, lakes, and coastlines reflects this preference for aquatic prey. In regions like the Pacific Northwest, spawning runs of species such as salmon and trout become a major food source during late summer and fall.
Eagles regularly consume other fish, including herring, flounder, catfish, and shad. They target medium-sized fish, often ranging from 14 to 30 inches in length. This preference is driven by the fact that larger fish offer more sustenance while still being manageable to carry in flight. The eagle will almost always choose fish over red meat when given the option.
Hunting Birds and Small Mammals
When fish are scarce, bald eagles readily switch to hunting birds and small mammals. Waterfowl are a common secondary food source, including ducks, coots, and geese. Eagles often target migrating or injured birds, which are easier to capture in flight or on the water’s surface.
Small mammals also constitute a regular part of the diet, especially near marshes and grasslands. Prey items include rabbits, squirrels, prairie dogs, and muskrats. The eagles’ sharp eyesight allows them to spot these creatures from high perches or while soaring. Occasionally, they opportunistically take reptiles, amphibians, and invertebrates like crabs.
Acquisition Strategies: Hunting, Scavenging, and Stealing
The bald eagle employs a multifaceted strategy to acquire food, encompassing active hunting, scavenging, and theft. Hunting for fish involves swooping down over the water and snatching prey near the surface with powerful talons. They rarely fully submerge themselves and have small bumps on their feet, called spicules, that help them securely grip slippery fish.
Scavenging is an energy-efficient component of the diet, particularly during winter or when live prey is difficult to find. Eagles feed on dead fish washed ashore, as well as the carcasses of larger mammals like deer and elk. This opportunistic behavior ensures survival when the weather limits their ability to hunt.
The eagle is also known for kleptoparasitism, which involves stealing food from other animals. They commonly harass smaller raptors, most notably ospreys, chasing them in the air until the victim drops its freshly caught fish. This technique is prevalent among younger, less experienced eagles who have not yet mastered hunting skills.
Regional and Seasonal Adaptations in Feeding
The bald eagle’s diet is highly flexible and shifts based on the environment and time of year. Northern populations, where water bodies freeze during the winter, rely heavily on scavenging and mammalian prey. During this time, they often congregate to feed on available carrion, such as roadkill or deer carcasses.
Conversely, eagles inhabiting coastal areas, where the ocean remains unfrozen, maintain a high fish diet year-round. Spawning fish runs, like those of chum salmon in Alaska, create temporary feeding opportunities that attract eagles from distant regions. The nesting season also drives a dietary shift, as parents require a steady supply of high-protein food to deliver to their young several times a day.