Wednesday, May 03, 2006
Wednesday May 3
Some great bald eagle life history info from Arthur Cleveland Bent's Life Histories of North American Birds:
On the growing eaglets:
"With the increase in size and strength comes an increase in activity, with more time devoted to play and exercise in preparation for flight. Activities begin by walking or jumping about the nest, which soon becomes trodden quite flat, picking up and playing with sticks, learning to grasp objects in the talons, and stretching and flapping their growing wings. With tail raised and head lowered the eaglet backs up to the edge of the nest and shoots its liquid excreta clear of the nest to form a "whitewashed" circle on the ground below.
"Later on the flight exercises begin in earnest, of which Dr. Herrick (1924c) writes:"
"After a while a simple routine is established--raising the wings until they seem to touch over the back, taking a few strokes and jumping; the flapping gradually comes to take their feet above the floor of the eyrie and at eight weeks of age they may be able to rise two feet or more in the air; this ability attained, they are liable to go higher and higher and in a fairly stiff breeze, which helps to sustain if not stimulate them, they begin to soar and hover. In 1922 we said "good-bye" to the Eaglets more than once before knowing the long practise they required to produce that perfect coordination of muscles and nerves which was necessary for confidence in the air. During the last week of regular eyrie life in that year they would sometimes rise to a height of fifteen feet, and soar for a full minute, going even beyond the confines of the nest and always with talons down to facilitate landing upon their return."
and on food:
"The large amount of food found in the nests of bald eagles containing young indicates that the eaglets, even when small, are fed on much the same food that the adults eat, or that the adults devour much of the food that is brought to the nest, or perhaps both. Mr. Pennock found in a nest with two very young eaglets, "certainly not over a few days old," an entire black duck, a headless black duck, and a headless mullet that had weighed 1 1/2 to 2 pounds. In another nest he found a partly eaten lesser scaup duck, and entire horned grebe, and three other grebes more or less mutilated. Mr. Nicholson says that the amount of food found in the nests is astonishing, and often much of it has not been touched. He lists rabbits, mostly marsh rabbits, other undetermined mammals, turtles, coots, Florida ducks, lesser scaup ducks, pied-billed grebes, little blue herons, snowy egrets, terns, killdeers, catfish (by far the most frequent species found and some up to 15 pounds in weight), black bass, seargeant fish, crevalle, pompano, and other fish. Under one nest he found between 40 and 60 skulls of mammals, about the size of rabbits. He has never found snakes in an eagle's nest, nor has he ever seen wool or bones of lambs, even in the heart of the sheep country. There is no doubt, however, that bald eagles do occasionally carry off lambs, as several good observers have seen them do it, and the bones have been found in and under their nests. Probably many of these were picked up dead, but sheep herders generally regard eagles as destructive enemies."
at May 03, 2006