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Tracking a bald eagle from birth near Anchorage's Potter Marsh

  • Author:
  • Updated: September 28, 2016
  • Published September 6, 2015

For all their majesty and dominance, an eagle's first year of life can be tough. The mother may lay anywhere from one to three eggs, but usually just one chick -- often the first to hatch -- survives to leave the nest. On average, each baby eagle has less than a 50 percent chance of making it through its first year of life; some experts place a juvenile eagle's overall mortality rate at up to 75 percent.

So far, so good for the family of bald eagles that photographer Bob Hallinen has tracked since April as they incubated at least one egg near the backside of Potter Marsh in Anchorage. The adult pair then nourished the resulting ball of gray fluff into a healthy, chocolate-brown juvenile that has, to all appearances, successfully left the nest.

A mated pair of eagles eagles share incubation and feeding duties, but usually the female does the bulk of the incubating while the male does most of the hunting. That's because the female's larger body size -- up to 14 pounds, with a wingspan of up to 8 feet -- is best suited to incubating the egg and the chick, while the male's slightly smaller size -- up to 10 pounds with a 6- to 7-foot wingspan -- gives him better agility for hunting. All in all, the process takes three months from egg to fledgling, followed by another month of feeding by the parents before the new eagle sets out on its own.

The juvenile that Bob photographed may wander thousands of miles, crossing the continent as it slowly molts into its adult colors. Until the conspicuously white head and tail of the adult develop, juvenile bald eagles are easily mistaken for golden eagles. You can tell the two apart by looking for the juvenile baldie's whitish wing linings on the forward part of its wings as well as the bare lower legs. A golden eagle's legs are feathered all the way to the feet.

Despite a tendency to wander, most young eagles come back to nest within 250 miles of their birthplace once they reach maturity at 4 or 5 years of age. In the wild, they may live for 30 years or longer. If the chick does come back and roost close to home, the odds are good it'll live a long life. Our state has always been a stronghold for the species, which was finally removed from the list of threatened and endangered species in 2007, after a nearly 30-year tenure.

By far, many more eagles live in Alaska than any other state with estimates ranging above 30,000, according to the Alaska Department of Fish and Game. But the raptors' history here hasn't always been easy. Nearly a century ago, the Alaska Territorial Legislature imposed a bounty on eagles over concerns from fox farmers and commercial fishermen that the birds were harming their businesses. Before the Bald Eagle Protection Act of 1940 passed, an estimated 100,000 were killed.

So next time you're walking in a tree-lined area and hear an alien twittering -- kind of like a DJ scratching with a squeaky wheel -- stop and look around. Movie directors often dub in the call of a red-tailed hawk when they show an eagle soaring, but that squeaky twitter is an eagle's true call. And in another few years, that sound might just be coming from the fledgling that Bob captured trying out its wings for the first time, all grown up and come home to build a nest of its own.

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