The bald eagle, North America’s iconic raptor, is an impressive predator recognized for its powerful flight and distinctive white head. While they are opportunistic feeders that consume a variety of prey, fish is overwhelmingly their preferred and most common food source. This dietary preference dictates where the eagles live, often placing them near large bodies of open water like coasts, rivers, and lakes.
Fish: The Primary Diet Staple
Fish constitute the majority of a bald eagle’s diet, often making up 70% to 90% of its total food intake, depending on the geographic location and season. This substantial reliance on aquatic prey influences their choice of habitat, ensuring they are never far from a reliable fishery. The nutritional profile of fish offers high protein content, which is readily digestible and supports the eagle’s energetic needs, especially during nesting and migration periods.
Eagles are not particularly selective about the species they consume, with over 100 different fish species recorded in their diet. Common catches include Pacific salmon, trout, herring, catfish, and various carp species. They often target fish that are slower, surface-swimming, or already sick, injured, or dead, which conserves valuable energy compared to pursuing healthy, fast-moving aquatic life. For instance, in the Pacific Northwest, eagles congregate to scavenge the carcasses of spawned-out salmon, which provide an enormous and easy food supply in late summer and fall.
The eagle’s digestive system possesses strong stomach acids that can dissolve small fish bones completely, providing an important source of calcium. This ability to digest bone is particularly beneficial for female eagles during the egg-laying season. The size of the fish consumed can vary widely, but eagles prefer items typically ranging from 8 to 30 inches in length.
Aquatic Hunting and Foraging Techniques
Bald eagles use a combination of active hunting and strategic foraging to secure their meals from the water. They possess exceptionally sharp eyesight, which is significantly better than human vision, allowing them to spot movement from great distances while soaring or perched high in a tree. Once prey is sighted near the water’s surface, the eagle executes a rapid, controlled descent.
The primary hunting method is a shallow strike, where the eagle glides down, extending its legs forward at the last moment to snatch the fish with its powerful talons. Unlike ospreys, bald eagles generally avoid fully submerging their bodies into the water, aiming to grab the prey without losing momentum or becoming waterlogged. Their talons feature rough, spiky projections, called spicules, on the pads of their feet, which provide a vise-like grip to prevent slippery fish from escaping during the flight back to a perch.
A distinct and common foraging technique is kleptoparasitism, the act of stealing food from other animals. Eagles frequently harass other birds that have successfully caught fish, most notably ospreys, forcing them to drop their catch in mid-air. This tactic allows the eagle to acquire a meal with minimal physical effort and risk, demonstrating their highly opportunistic nature. They will also steal food from other raptors and mammals, securing a meal they did not have to hunt themselves.
Dietary Flexibility and Opportunistic Feeding
While fish is the dietary backbone, bald eagles are highly adaptive and will consume a wide variety of other prey, especially when fish is scarce. This flexibility allows them to survive in diverse environments and during lean seasons, such as when water bodies freeze over in winter. In these conditions, the eagle switches its focus heavily toward scavenging.
Carrion, or dead animal matter, becomes a significant food source during the colder months, with eagles often feeding on the remains of deer, elk, or other large mammals found along shorelines or roadsides. This scavenging behavior is a low-energy way to meet their daily food requirement, which can range from half a pound to a pound of food.
Beyond fish and carrion, the eagle’s opportunistic diet includes other live prey like small mammals such as rabbits, squirrels, and moles. They also readily hunt birds, particularly waterfowl like ducks and coots, often targeting young or injured individuals. Reptiles, including turtles and snakes, are also occasionally taken, rounding out the eagle’s diverse menu. These non-fish items ensure the raptor’s survival when its preferred aquatic prey is unavailable or too difficult to catch.