Posts Tagged ‘Golden Eagle’

OF EAGLES AND SUCH

July 18, 2017

Harry Fuller writes: Recently a long-time friend, Dr. David Sachs of Palo Alto, sent me a great photo of a fish eagle taking a fish from a lake in Zimbabwe. He asked a little about the eagle and I inadvertently buried him in data.
David, I got your recent note with the action shot of the African Fish Eagle. Kate and I saw this bird several times around the lakes in Uganda. Handsome bird. Yes, the fish eagle would carry food back to brooding mate and then to young after they hatch. The nest would never be left unguarded once the first egg is laid. And the nest has to be protected from such possible nest thieves as Red-tailed Hawks and Canada Geese. Even winter nesting Great Horned Owls are known to steal an Osprey’s nest that has been years in the building. The owls nest even before many Osprey have returned to their nesting territories. Many large birds (storks, eagles and osprey) will usually return to previous year’s nest if they can, and simply repair and remodel. Then young eagles will spend over a month in the nest before they can even begin to try short flights and then they are fed wherever they perch after leaving the nest. To become an adept predator a young bird needs lots of practice and parental support. At least their “college” is free.
The African Fish Eagle is in the same genus as our own Bald Eagle and the White-tailed Eagle of Northern Europe. They are all in Haliaeetus genus. Haliaeetus is a compound of two Greek words, translated literally as “sea eagle.” Our Bald Eagle is not really a “sea eagle,” more strictly a bird of marsh, lake and river though it will fish in quiet salt-water lagoons and estuaries. The fish eagle is smaller than our Haliaeetus eagle and the European one. It is less than thirty inches tall. An adult Bald Eagle will be at least 31 inches tall and the female (which is always the larger of the pair) can be over three feet tall with a wingspan up to 7 feet or more. Our Bald Eagle does fish but in winter often lives on carrion from dead waterfowl as large as swans. This eagle has evolved an immunity to avian cholera and botulism which is handy in winter when large number of migrants waterfowl sicken and die on any over-crowded wintering range.
I have always though the Bald Eagle—contra Benj. Franklin who favored the Wild Turkey—was a perfect symbol for our money-mad country. This eagle will catch its own fish but often uses theft, bullying or simply good luck to find food. Other birds’ diseases leave carrion for eagles, ditto road kills. An eagle pair is great at ganging up on a hard-working Osprey (almost a pure piscine feeder) and stealing its fish. I have also seen eagles take ground squirrel away from Red-tailed Hawks. The Bald Eagle is sort of a hedge fund manager looking to make off with anybody’s else’s hard work or profit for its own selfish good. They are pretty good parents, of course. But among adults there is only begrudged sharing of a carcass. Often one eagle will have found carrion and a coterie of ravens will land just out of reach, waiting for the scraps. The Bald Eagle has one other great strength which is its great strength. It can easily remove bits of frozen deer or goose flesh from a hard-frozen corpse. Some scavengers like ravens and Turkey Vultures lack that strength. Eagles can winter anywhere there is food, fresh or frozen. However, the Turkey Vulture must migrate south to where the nights are warm enough to not freeze a carcass solid. On the Pacific Slope that is generally south of Redding or along the coast. Now, with global warming, a few vultures are wintering in Willamette Valley.
Our other native American eagle is the Golden. It’s a member of the large tribe in the Aquila genus. Aquila is Latin for “eagle” and especially refers to a sharply hooked beak. It is believed that “eagle” derived from old French word “agile” which in turn derived from the original Latin.
Our Golden Eagle has cousins all over the world, most smaller in size. The American Golden females can be up to 40 inches tall. Most of the Old World eagles in this genus are less than three feet and most are some shade of brown with little bold patterning (except the bright white on the Wahlberg’s Eagle). These are birds of mostly open terrain. Our Golden is a specialist in catching jack rabbits and other denizens of our grasslands and prairie. This bird takes talon strength to the max. It can muster several hundred pounds per square inch pressure when it grabs prey. It generally hits prey from behind and kills quickly by crushing the victim. They often nest high in tall trees or on cliff faces in dry areas where there are no trees. Nobody bothers a Golden Eagle in any serious way in daylight.
Two quick stories: I once saw a territorial male Osprey go about trying to drive off a Golden Eagle soaring over a hillside near the Ospreys’ nest. Twice the Osprey screamed and then dove down toward the eagle’s back…each time the eagle flipped over onto its back at the last instant and invited the Osprey to come on down. The eagle’s talons were open and waiting. Each time the Osprey swerved off at the last minute. Those talons would have meant a crushing defeat and death, literally.
A friend in Ashland lives out in the parched, grassy hillsides of the lower Cascades. The Golden Eagle and the Red-tailed both hunt there regularly. A pair of Golden Eagles were nesting on a rocky point uphill from my friend’s house. He often saw the smaller and more agile Red-tails harass the eagles as they hunted, hauled food to the young, built their nest. This is common in avian world—smaller, quicker birds pester bigger, slower predators. I’ve even seen blackbirds go after a vulture which eats only carrion. An angry hummingbird can drive off a huge raven. My friend was out on his hillside planting oak saplings to restore the chaparral that was once there. He saw a Red-tail swoop down the slope and nail a California ground squirrel. Then the hawk tried to get a good grip to haul away its fairly weighty prey. Shortly my friend sensed a big shadow speed by and looked up to see a Golden Eagle hit that Red-tail from behind. Astounded, he watched the eagle tear apart the hawk and the squirrel, fairly efficiently, then fly off. Nothing was left on the ground but shredded bits of both creatures. Apparently the Golden Eagle was settling an old and bitter score.
“Eagle” is an old English word thrown around in naming many unrelated species in the Old World. Some eagles there would be simply big “hawks” here. We would not consider a bird less than two feet tall worthy of that grand a moniker. There are even now birds commonly named “hawk-eagle,” go figure. Perhaps the most striking of the African eagles is the Bateleur, 28 inches tall. In the Old World “buzzard” is synonymous with “buteo,” the genus of our Red-tails. “Vulture” in old world is a group of large predatory birds, not strictly scavengers like our vultures and condors who are actually well-adapted members of the stork family, unrelated to Old World vultures. So it goes in the world of taxonomy vs. common lingo.

Here’s my own shot of a pair of fish eagles perched in a forest in Uganda, taken on an PIB-sponsored trip:FISH EAGLES