Every few years a story goes around about a bald eagle carrying off a dog, or trying to snatch someone's cat. It's far-fetched, but it's not impossible.
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Biologists who study birds of prey and folks who live around eagles have seen plenty of snatching and carrying - as well as swooping and swimming - and can offer insights into what eagles really can or cannot do.
Bald eagles are strong, aggressive birds, but like everything that flies, they are governed by aerodynamics. The wings of an eagle need to support the 8 to 12-pound bird as well as whatever the bird is carrying, and best estimates put the lifting power of an eagle at 4 or 5 pounds. But it's not quite that simple.
Lift is related to wing size and airspeed. The faster a bird (or plane) is flying, the greater the lift. An eagle that lands on the beach to grab a fish, and then takes off again, can carry less than an eagle that swoops down at 20 or 30 mph and snatches up a fish. Momentum and speed give the bird the ability to carry more weight.
Biologist Ron Clarke earned his master's degree studying birds of prey, and he's a falconer who trains raptors. He hunts with a gyrfalcon and a peregrine falcon, and said his 45-ounce gyr can carry an 8-ounce bufflehead duck pretty easily.
"He can't do the same with a mallard, though," he said. At about 2 pounds, a mallard is four times the weight of a bufflehead.
Clarke said an eagle with momentum is a different story.
"On a wide-open beach, I have no doubt that an eagle with a full head of steam could pick up a 6- or 8-pound dog and just keep on going," Clarke said. "If it landed to kill a 10-pounder, and then tried to pick up and fly from a dead stop, could it get off the ground? Probably not."
Eagles will carry heavier loads a short distance. Mike Jacobson, who is recently retired, spent decades as an eagle management specialist for the U.S. Fish and Wildlife Service.
"There used to be stories about eagles carrying off babies and little kids, and none of that has ever been documented," he said. "They can pick up and carry 4 or 5 pounds, maximum, and actually fly off with it. They can lift a little more and hop it along, but they can't carry it off."
Flying may be an eagle's birthright, but it requires skill. Falconers and bird-watchers can attest that swooping down to nab dinner or snatching food off the water, requires techniques that are honed with experience. Young predators develop their hunting skills by trial and error, play, and testing limits. Young eagles will swoop on floating bottles, attempt to lift salmon that are too heavy, and investigate new objects.
Jacobson said an immature eagle is most likely to swoop down on something inappropriate, such as a dog on the beach. People then overreact and claim that eagles are hunting dogs.
"It gets exaggerated" he said. "Eagles don't hunt cats and small dogs."
Fish makes up the vast majority of Southeast Alaska eagles' diet. In other areas, the diet varies more, as eagles take advantage of local opportunities, Jacobson said. Eagles that live near seabird colonies will eat more birds, and eagles in the Interior take more birds and small mammals than eagles in Southeast Alaska. Jacobson once saw an eagle carrying a mink and he's heard stories of eagles carrying small muskrats. Eagles in the Aleutians are known to prey on sea otter pups during pupping season. But fish are bald eagles' bread and butter.
Other eagles are different. Jacobson said golden eagles are comparable in size and weight to bald eagles, but they target different prey.
"Golden eagles are not bigger or stronger, but they have very different behavior," he said.
Although bald eagles don't actively target cats, Jacobson has heard a few stories that seemed plausible. A small cat is certainly within an eagle's abilities.
"Eagles have occasionally nailed people's cats," he said. "It's rare, but people do see them swoop down on cats sometimes."
David Hunsaker once found a cat collar in an eagle nest. The nest is right outside the window of his Tee Harbor home, and he's done a great deal of eagle watching over the past 15 years. He and his wife watched a pair of eagles build the nest, and they've seen eagles incubate eggs, deliver food and raise a number of broods of chicks. They've watched the chicks grow and fledge.
"The cat collar was funny," he said. "It had a bell attached to warn birds. It was still buckled."
Hunsaker added that the collar doesn't necessarily prove that the eagles carried a cat to the nest. He also found a baby's rattle in the nest. "I envision that rattle clutched in a chubby fist," he said, "but it's not likely the eagles caught a child."
It's also possible the cat was a scavenged roadkill. Over the years, Hunsaker has seen fur in the nest a few times, and the eagles have brought home a few bloody birds, but he said the eagles almost exclusively eat fish.
"The majority are herring or smelt, small fish about 8 inches long," he said. He's seen plenty of salmon delivered to the nest, usually in pieces. "They'll bring half a salmon, usually a pink, then take off and come back with what appears to be the other half. So they dismember it somewhere. I've never seen them bring a full coho or sockeye, but pieces."
Hunsaker doubts the accounts of eagles taking small dogs not because they couldn't carry it, but because in his observations, eagles are very wary of people. Although the nest is near the house, the birds don't roost on the peak of the house, the deck or nearby power poles.
"They are really skittish around people," he said. "They are not going to snatch a dog off a leash, or right in front of the owner."
Biologist Phil Schempf works for the U. S. Fish and Wildlife Service in raptor and migratory bird management. He has no doubt an eagle could kill a small dog or cat if the opportunity presented itself, and carry it or at least pieces of it to a nest.
"My feeling is that it doesn't happen very often though," he wrote in an e-mail. "I'd speculate that is due to eagles being leery of approaching people or foraging in novel areas such as people's yards. Eagles typically are foraging along beaches or riparian areas where it is rare for dogs and cats to be unattended by their owners."
Riley Woodford is the editor of "Alaska Fish and Wildlife News" and he produces the "Sounds Wild" radio program for the Alaska Department of Fish and Game. Photographer Jeff Mondragon's work can be seen at mondragonphoto.com.