Occasionally an interview is so compelling it’s better published as is. My recent Q&A with Jim Watson, a raptor research scientist with the Washington Department of Fish and Wildlife, is a case in point. Watson has spent 40 years in the field studying bald eagles. I could think of no better person to interview regarding the hunting prowess of America’s national bird and Watson didn’t disappoint.

Doggett: Jim, can you describe some bald-eagle hunting tactics that impressed you?

Watson: Mated pairs of adult bald eagles hunting in tandem are impressive. On the Lower Columbia River I once observed a pair of eagles hunting waterfowl. The male eagle circled low over the ducks and forced them to dive under water and then resurface.  After he circled them two or three times, the female eagle flew in from the blindside direction and took a duck when it surfaced and was looking in the opposite direction. The eagles shared the meal.

Bald eagles, like most raptors, are resilient and able to overcome limitations while hunting. While capturing eagles at a banding station we observed a young eagle arrive at the carrion bait well before dawn in the darkness, and much earlier than other eagles.  Through our binoculars we were able to see the young eagle hop from place to place while feeding. It wasn’t until dawn that we could see the eagle only had one leg, but he departed with a full crop before other eagles arrived, when he would have had a difficult time competing for the carrion.

While watching an adult bald eagle pursue a gull with a small fish in his bill I expected a quick end, which occurred but not quite as expected. After pursuing the gull for five minutes, the exhausted gull conceded and dropped the fish—and the eagle proceeded to pounce on the back of the smaller bird and fly away with it.

Doggett: Is there a name for the hunting technique employed by bald eagles?

Watson: Bald eagles are “sit and wait” predators that maximize hunting success most often by 1) perching along open water and scanning with their keen eyesight for the opportunity to grab a live fish; 2) perching over open land such as tide flats, shorelines, or fields to detect other scavengers like ravens at a carrion source, and usurping them from the carrion; or 3) watching for other avian predators (e.g., gulls, other eagles) to successfully capture prey, and chasing them to force them to drop the prey (piracy).

Doggett: What are the bald eagle’s top hunting attributes?

Watson:  Eyes — raptors have two fovea (retinal depressions) and increased nerves in eyes that provide for both monocular and binocular vision. This allows them to see near and distant objects with high clarity. Also, raptors have a superabundance of rods and cones in their retinas that provide increased light and color clarity compared to humans. A study several years ago suggested the shape of raptor foveas may act as a telephoto lens to magnify images significantly for raptors, but the enhanced visual acuity and image quality from structure of the fovea may be equally important for detecting prey.  Magnification is probably 3x-4x rather than the often-reported 10x.  

Wings – bald eagles fly with power more than finesse, compared to other raptors like falcons and accipiters. One of my mentors, Alan Harmata, who I assisted with raptor work in the early 1970s, was ground-tracking a bald eagle with his Ford pickup but lost it after he hit 90 mph and the eagle flew out of view. This power and speed are essential in acquiring prey both in the air and water; bald eagles are powerful swimmers and easily can traverse a lake with a fish in tow.    

Feet – raptor feet are perhaps the most unique aspect of this avian group with grasp strength and sharp talons characteristic. Bald eagles lack the opposable toe and barbed pads on the feet like osprey that are specialized for grasping slippery fish. Rather, bald eagles have the classic triad of fleshy toes that provide the death grip for a variety of prey types and sizes.

Doggett: Just how powerful is their death grip?

Watson: To my knowledge, grip strength has only been tested in a laboratory for raptors smaller than eagles. Speculation is that an eagle’s grip strength is up to 400 psi, or about 5x that of a human. I’ve been footed twice by eagles during banding operations and the pressure is best described as constant and intense. It requires two people to pry the talons away.

Doggett: Can bald eagles capture fish under water?

Watson: Bald eagles are not adapted to dive regularly into water to capture prey, especially fish. Unlike osprey, they lack a valve in their nares that close to prevent them from inhaling water if they were to dive. Bald eagles most often take fish from just below the surface of the water whereas osprey may dive 2 or 3 feet. Neither species is adapted to be in open water more than a few seconds or their feathers will become water-logged and the bird will have to swim to shore.

Doggett: Roughly what is the ratio of bald eagles eating prey versus carrion?

Watson: In Washington, breeding adult eagles capture an average of 73% live prey, 15% scavenged prey, and 12% pirated prey. These percentages vary; in marine and bay habitats scavenging ranges from 10% to 19%, but only 0% to 3% on rivers and lakes. Mainly fish (78%), with fewer birds (19%) and mammals (3%), but these vary by habitat.

Doggett: Is there validity to reports of dog and cat collars being found in bald eagle nests?

Watson: Urban legend. Adult bald eagles that are very adept at hunting live prey much prefer to grab a live fish than tangle with a dog or cat. I’ve observed a young, inexperienced eagle grab a house cat, but the encounter lasted only 10 seconds or so as the fury of the cat caused the eagle to drop it a few feet above ground.

Doggett: What is the most surprising thing you’ve found in a bald eagle’s nest?

Watson: A T-bone steak (eaten).

Scott Doggett is a former staff writer for the Outdoors section of the Los Angeles Times. He and his wife, Susan, live in Port Townsend.