Eagles

Evaluating Predation by Eagles
Both bald and golden eagles may prey on livestock, but usually golden eagles, are responsible. Both species readily accept livestock carrion and carcasses of foxes and coyotes, although some individuals may prefer live prey to carrion. Eagles are efficient predators and they can cause severe losses of young livestock, particularly where concentrations of eagles exist. Generally, they prey on young animals, primarily sheep and goats, although they are capable of killing adults. Golden eagles also take young deer and antelope, as well as some adults.

Eagle Predation – Description

Both bald and golden eagles may prey on livestock, but usually golden eagles, are responsible. Both species readily accept livestock carrion and carcasses of foxes and coyotes, although some individuals may prefer live prey to carrion. Eagles are efficient predators and they can cause severe losses of young livestock, particularly where concentrations of eagles exist. Generally, they prey on young animals, primarily sheep and goats, although they are capable of killing adults. Golden eagles also take young deer and antelope, as well as some adults.

Eagles have three front toes opposing the hind toe or hallux on each foot. The front talons normally leave wounds I to 3 inches apart, with the wound from the hallux 4 to 6 inches from the wound made by the middle front talon. On animals the size of small lambs and kids, fewer than four talon wounds may be found, one made by the hallux and one or two by the opposing talons. Talon punctures are typically deeper than those caused by canine teeth and somewhat triangular or oblong. Crushing between the wounds is not usually found, although compression fractures of the skulls of small animals may occur from an eagle’s grip. Bruises from their grip are relatively common on eagle kills.

Eagles seize small lambs and kids anywhere on the head, neck or body; lambs are frequently grasped from the front or side. Eagles usually kill adult animals and lambs and kids weighing 25 pounds or more by multiple talon stabs into the upper ribs and back. Their feet and talons are well adapted to closing around the backbone, with the talons puncturing large internal arteries, frequently the aorta in front of the kidneys. Massive internal hemorrhage from punctured arteries and/or collapse of the lungs when the thorax (ribcage) is punctured contribute to shock as the major cause of death. Eagles may also simply seize young lambs, kids or fawns and begin feeding, causing the prey to die from shock and loss of blood as they are eviscerated.

Eagles skin out carcasses, turning the hide inside out, and leave much of the skeleton intact with the lower legs and skull attached to the hide. However, on very young animals, the ribs are often clipped off neatly close to the backbone and eaten, although eagles frequently do not eat the sternum (breast bone). Some eagles clip off and eat the mandible (lower jaw), nose and ears. Quite often, they remove the palate and floor pan of the skull and eat the brain. They may clean all major hemorrhages off the skin, leaving very little evidence of the cause of death, even though there may be many talon punctures in the skin. Ears, tendons and other tissues are sheared off cleanly by the eagle’s beak.

Larger carcasses heavily fed on by eagles may have the skin turned inside out with the skull, backbone, ribs and leg bones intact, but with nearly all flesh and viscera missing. However, the rumen is not normally eaten. Eagles may defecate around a carcass, leaving characteristic white streaks of feces on the soil and their tracks may be visible in soft or dusty soil.