Birds of prey, commonly known as raptors, are carnivorous birds characterized by their predatory lifestyle. The term “raptor” comes from the Latin word “rapere,” meaning “to seize” or “to take by force.” Raptors are defined by physical adaptations, including sharp talons, hooked beaks, and exceptional eyesight, specialized tools for hunting and consuming animal flesh. Although the specific menu varies widely, the entire group shares a diet centered on the capture and consumption of other animals.
The Core Diet and Prey Categories
Raptor diets are hypercarnivorous, consisting almost entirely of animal matter. The spectrum of prey encompasses nearly every animal class, though the majority focus on vertebrates. Small mammals, such as voles, mice, and rabbits, form a foundational food source for many hawk and eagle species.
Birds are another significant prey category, particularly for fast-flying raptors like falcons. Reptiles and amphibians, including snakes, lizards, and frogs, are commonly taken, especially in warmer climates. Invertebrates, mainly insects, constitute a substantial portion of the diet for smaller raptor species, such as kestrels.
Fish is the exclusive diet for specialized raptors like ospreys and sea eagles. Carrion, or dead animal flesh, is a secondary food source for many raptors, but it is the primary diet for vultures.
Specialized Hunting Adaptations
Raptors possess physical features that enable their predatory existence. Their powerful feet are equipped with sharp, non-retractable talons, which are the primary weapons for seizing and killing prey. Talons deliver a fatal squeeze or crush the spine of the captured animal.
Once prey is secured, the hooked beak tears flesh and dismembers the meal. The upper bill of many falcons features a sharp cutting edge, sometimes referred to as a “tomial tooth,” which aligns with a notch in the lower bill to sever the spinal cord of their prey.
Exceptional eyesight is the most defining sensory adaptation, with some eagles possessing vision up to eight times sharper than that of a human. This acuity allows them to spot small prey from immense distances while soaring. Owls have evolved specialized, fringed flight feathers that enable virtually silent flight, allowing them to surprise prey during nocturnal hunts.
Dietary Variation Across Raptor Groups
The vast range of raptor species has led to diverse dietary specializations driven by habitat and morphology. The Osprey, for instance, is a piscivore, relying almost entirely on fish, facilitated by a reversible outer toe and spiny pads on its feet to grip slippery aquatic prey.
Carrion specialists, such as vultures, have evolved unique physiological traits to handle their diet of decaying flesh. Old World vultures have featherless heads and necks, which prevents fouling from blood and tissue. Their digestive systems have an extremely low pH level, which helps neutralize the harmful bacteria and toxins found in rotting meat.
Nocturnal hunters, like owls, primarily target small mammals, relying on acute hearing and silent flight to locate rodents. Diurnal raptors, such as Accipiters like the Goshawk, are frequently bird-hunters, using their short, broad wings and long tails to maneuver quickly through dense forest environments to chase down avian prey. Certain kites and American Kestrels demonstrate a preference for invertebrates, often hunting insects like grasshoppers.
Processing and Digestion
After a raptor consumes its meal, the digestive process begins with the crop, a pouch located in the esophagus that serves as temporary storage for food. Owls are one of the few raptor groups that lack a true crop, instead having a simple widening of the esophagus. Food then passes into the stomach, which is divided into the glandular proventriculus and the muscular gizzard.
The proventriculus secretes highly acidic digestive juices and enzymes to break down soft tissues like muscle and fat. The acidity of the stomach varies significantly between species; for example, the stomachs of hawks and eagles are often so acidic that they can dissolve bone. This efficiency means that many diurnal raptors digest nearly all parts of their prey except for fur and feathers.
The indigestible components, such as bones, teeth, fur, and feathers, are compacted in the gizzard into a dense, oval mass known as a pellet. This pellet is subsequently regurgitated, or “cast,” typically hours after a meal and before the next hunt. Owls, whose stomachs are generally less acidic than those of many hawks, tend to produce pellets that contain more intact bones, providing researchers with clear evidence of their recent diet.