Accounts of eagles carrying off dogs and cats are unsubstantiated and highly unlikely. An eagle can lift about three or four pounds, more if it swoops down. 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 about 4 pounds. That varies, however, depending on the circumstances. Lift is dependent on air speed as well as wing size. The faster a bird (or airplane) is flying, the greater the lift potential. An eagle that lands on the beach to grab a fish and take off is limited to a smaller load than an eagle that swoops down at 20 or 30 miles an hour and snatches up a fish. Momentum and speed give the bird the ability to carry more weight.