The bald eagle is not only our nation's most recognizable natural symbol, and the only eagle found exclusively in North America, it is also the endangered species act's most prominent success story, and a reminder of how important are the protection of our wildlife, critical habitat and natural resources generally.

Populations of breeding pairs of bald eagles in the lower forty-eight states crashed in the late sixties to just over 400 pairs, due to hunting, habitat destruction and most prominently, the use of chemical pesticides in agriculture, such as DDT. In a scary process, known as "biomagnification" , bald eagles, being an apex predator at the top on their food chain, and feeding mainly on  fish, occasional small rodents and carrion, in other words, wildlife which had themselves absorbed toxins in various forms ultimately from pesticide-laden vegetation or runoff from agricultural fields, suffer highly concentrated, elevated levels of these toxins, negatively impacting birth and mortality rates. Calcium deficiencies caused by the toxins resulted in the thinning of egg shells, which would collapse under the nesting female's weight, causing a nosedive in successful eaglet births.

The Endangered Species Act of 1973 was the result of the attention called to these and related problems by wildlife lovers, falconers, hunters and others concerned about the fate of our native species. With the banning of the pesticides most harmful to wildlife in the United States, eagle numbers recovered, with the result that the bald eagle went from "endangered" to "threatened", and to finally "delisted" in 2007, as mating pairs reached over 11,000 in the lower forty-eight. Eagles were never as threatened in Alaska and British Columbia, and Alaska still has about 80% of the World's bald eagles.  Many raptors joined in the recovery, due to the banning of these pesticides, most notably, the peregrine falcon.

Of course, the problem with pesticides is far from over, as most folks don't realize that the sale of these pesticides was banned by the EPA in the U.S., and later in many other western nations, but they are still being used in Africa, Asia  and South America. DDT is said to help fight malaria in third world nations, and Swainsons Hawks, which nest on the Canadian-American prairies, remain on the endangered species list, because they winter on the Argentine Pampas, where Swainsons die-offs from an inexpensive but lethal pesticide, monocrotophos, were still a problem in the late nineties.

There is also a downside to "delisting". as it opens formerly protected critical habitat to development and some of the very pressures that contributed to the decline of the eagle in the first place.

Bald eagles disappeared from the Adirondacks by the early sixties, but in 1981, Peter Nye, an eagle biologist and leader of the Endangered Species Unit of the New York Department of Environmental Conservation, traveled to Alaska on a mission to repopulate the Adirondacks with bald eagles. Alaska has four times as many eagles as the rest of the country, so Nye's mission, in a process known as "hacking", was to take wild eaglets mature enough to care for themselves and just about ready to fly, transport them to New York, build nests protected from climbing predators like  fishers, gray fox and black bears, and release them in a remote area, unvisited by people, in the hopes that the eagles would begin breeding, nesting and repopulating New York.

A logical place to release them was Follensby Pond, a remote wilderness area of over 14,000 acres, once home to bald eagles, and the site of a famous get together in 1858 known as the "Philosophers Camp", which was organized by painter William James Stillman, and included poet and essayist Ralph Waldo Emerson, poet and diplomat James Russell Lowell and paleontologist, geologist and all around naturalist, Louis Agassiz.

The owners of the Follensby Wilderness, John and Bird McCormick, sold the property to the Nature Conservancy in 2008, on the condition that the Nature Conservancy work with New York State to ensure that the Wilderness remains wild, and inaccessible to the public, at least for the foreseeable future. It is here that Nye hacked the eagles, with the result that there are today in 2020 probably 24 nesting pairs of eagles in the Adirondacks, and over 200 pairs in New York State. Way to go, Pete!

The number one killer of the bald eagle in America today is lead poisoning, which the eagles pick up while scavenging the remains of game, mainly white tailed deer taken by hunters using lead based bullets, which shatter on impact, sending lead shards into flesh, often away from the path of the bullet. This is a problem easily solved by having hunters switch to solid ammunition, such as copper, but the NRA sees this as an attempt to take your weapons.

That’s like saying that when the state mandates seat belt use, that is an attempt to take your car, but such is the ridiculous logic employed in polarized political debate today. No one is saying don’t hunt, just change the type of ammunition you use. States like California have made this argument academic, by banning the use of lead ammunition, just as many states have banned the use of lead sinkers, which can be mistaken for pebbles and swallowed as aids in digestion by loons and other waterfowl.

 The bald eagle, a relative of the white tailed eagle found in temperate areas of Europe and Asia, lives  only in Canada, the U.S. and Northern Mexico, with eighty percent of bald eagles found in Alaska, and the density of eagles more pronounced along the west coast, particularly from Alaska down through British Columbia. Bald eagles are the largest North American raptor, averaging six and a half to fourteen pounds. and they are rivaled in size only by the golden eagle, which averages about a pound less. One bald eagle, unfortunately shot in New York in the 1890s, weighed in at 18 pounds.

All raptors display sexual dimorphism in size, with females being larger than males, and in the case of bald eagles, females average twenty five percent larger than males. We really don’t understand exactly why females are larger. My guess is the division of labor, with females spending more time on the nest than males, incubating eggs, and larger size is an advantage when defending the nest, while speed and agility are more important in hunting. Without a blood test, male raptors can’t be visually distinguished from females, and gender is usually guessed by size.

A large female measures about 36 inches in length, with a wingspan of 72 to 90 inches, and they can fly between 30 and 35 mph. They soar with a flat wing formation, and the wings are so powerful, they aid in swimming, as when an eagle tries to drag heavier prey through the water, pumping with those wings. As with other birds, eagle bones are hollow, making eagles lighter and better able to fly.

 Like your fingernails, their beaks, talons and feathers are composed of keratin. Eagles have about 7,000 feathers which are moulted individually in sequence from head to tail over about six months, which explains the gradual streaky transformation of the head and tail from brown to white. During their first year, immature eagles grow larger feathers than their parents to provide greater lift and compensate the lack of fully developed flight muscles. This is why first year eagles often look larger than their parents. Eagles make discordant, squeaky, gull like screams, which is why Hollywood movies substitute the more pleasing-to-the-ear cry of the red tailed hawk in scenes where eagles are featured.

Eagles also conform to Bergmann’s Rule, which says that average individual size is determined by suitability of habitat, such that larger animals are more likely to retain body heat and survive in colder climate, thereby surviving to pass along genes for larger body size when breeding. Bald eagles in Alaska are considerably larger on average than those in Florida. Bald eagle migration follows similar patterns, with eagles in colder climates moving further south in winter than those in more temperate climates, most of whom remain in their territories.

Bald eagles are usually monogamous, and a mating pair will use the same nest every year, like a home owner, constantly tweaking it and adding to it, with the result that bald eagle nests can measure ten feet wide and ten feet thick, weigh up to a ton and are the largest nests of any bird, aided by the fact that eagles can begin mating by their fourth or fifth year, and can live over thirty years. The record size nest is two and a half tons, but some nests eventually collapse under their own weight, and a new nest has to be constructed. The nest of our oldest bald eagle, Sylvia, was blown down in a Pacific storm while she was still a fledgling, resulting in the permanent disabling which resulted in her living with us. Her two male siblings were successfully rehabbed and released.

Nests are typically located very high in old growth conifer or hardwood trees, ranging from only twenty feet above water when the tree’s trunk is in the water, to 125 feet high when the tree is on land , protruding above smaller trees, and within two miles of large bodies of both salt and fresh water, with most within sight of open water. All else being equal, for example, the potential for scavenging deer and other carrion, and for kleptoparasitism, stealing fish from ospreys or carrion from other scavengers, a nesting pair will generally require a lake of at least four or five square miles in order to make a living.

Eagles cluster where the opportunity for fishing and scavenging is greatest. When on the Kenai Penninsula in Alaska, on the way to Homer, there is an old Russian Village called Ninilchik, where the fishing boats dump unwanted catch in Cook Inlet, and there are always dozens of bald eagle on the beach there in the warmer months. Homer Spit and the Chilkat River north of Haines are other areas of large eagle gatherings.

Immature bald eagles are often confused with golden eagles, as the white head and tail feathers, signs of sexual maturity, don’t finish gradually showing through feather moulting until the fourth or fifth year, as the developing white streaking becomes solid white. Other signs which differentiate bald eagles from golden eagles are the fact that golden eagles have feathers up and down the legs, like trousers, and a lighter brown plumage, as immature bald eagles start out a darker brown before the white feathers begin appearing.

We have a bald eagle at the Refuge who was shot as an immature eagle, but featured leucism, an excess of melanin, which led to lighter feather patterns to such an extent that we thought at first that it might be a young golden, until the head and tail streaking gradually showed it to be a bald eagle. Bald eagles also tend to have larger heads and beaks than goldens, and northern bald eagles have longer beaks than do southerly bald eagles. Immature bald eagles have darker beaks which gradually become solid yellow in maturity.

Eagles are strong fliers with incredibly powerful talons. The general rule seems to be that an eagle can carry and fly with prey up to half its body weight. It’s talons exert a grip of ten times a human’s hand, so somewhere between 500 to 700 pounds per square inch, which is nearly equal to a grey wolf’s bite, and why eagle handlers use those thick padded gloves. The rear talon is often used to puncture and kill prey held immobilized by the three front talons, as the talons on the other foot and the beak are used to tear prey apart.

Bald eagles not only have sharper vision than we have, but a wider field of vision. As with other raptors, eagles have a nictating membrane, an extra transparent eyelid which protects, moistens and cleans the eye. Eagles see in ultraviolet light, enabling them to detect urine trails of potential prey, just as UV enables some winter browsers like reindeer to spot lichen against the snow. Birds puff up their feathers for better insulation and to appear larger to predators.

Courting involves spectacular flight displays, with dives, swoops and aerial acrobatics in which eagles clutch each others talons and tumble through the air.

Eagles nest and breed earlier than other raptors, with the female laying one to four eggs in sequence between mid February and mid March, depending on climate and latitude, with hatching between mid April and early May, and branching and fledging late June to early July. As with some other raptors, older and larger siblings, those which hatch first may monopolize more food from its parents, by pushing younger siblings out of the nest. Eaglets grow quickly, gaining up to six ounces per day, beginning to flap their wings at 8 weeks, fledging between 8 to 14 weeks, and finally leaving the nest area about 8 weeks after fledging.

Steve Hall

Ben Franklin, the statesman, philosopher, naturalist, inventor and all around Renaissance Man, was not all that thrilled with the choice of the Bald Eagle as our national symbol, and seemed to prefer the wild turkey as a utilitarian symbol, which is uniquely American, and often spelled the difference between our wilderness forefathers eating or starving. In a letter to his daughter, Franklin said, in part.....

"For my own part I wish the Bald Eagle had not been chosen the Representative of our Country. He is a Bird of bad moral Character. He does not get his Living honestly. You may have seen him perched on some dead Tree near the River, where, too lazy to fish for himself, he watches the Labour of the Fishing Hawk; and when that diligent Bird has at length taken a Fish, and is bearing it to his Nest for the Support of his Mate and young Ones, the Bald Eagle pursues him and takes it from him.

"With all this Injustice, he is never in good Case but like those among Men who live by Sharping & Robbing he is generally poor and often very lousy. Besides he is a rank Coward: The little King Bird not bigger than a Sparrow attacks him boldly and drives him out of the District. He is therefore by no means a proper Emblem for the brave and honest Cincinnati of America who have driven all the King birds from our Country . . .

"I am on this account not displeased that the Figure is not known as a Bald Eagle, but looks more like a Turkey. For the Truth the Turkey is in Comparison a much more respectable Bird, and withal a true original Native of America . . . He is besides, though a little vain & silly, a Bird of Courage, and would not hesitate to attack a Grenadier of the British Guards who should presume to invade his Farm Yard with a red Coat on."

Of course, these days we often call politicians "turkeys", but I believe we have a different meaning in mind.

So....was Ben correct?

Well, yes and no. Bald eagles are opportunistic predators, and we have seen them steal fish from our local ospreys, but that is fairly standard behaviour for predators. Grizzlys will try to steal kills from wolves, but if there are more than two wolves, they will tease and harass the grizzly, until it gives up and leaves. Ravens will lead wolves to a winter killed-moose, but when the wolves are finished gorging, and are just lying around, the ravens will cover the carcass, but instead of eating, will cleverly steal and cache chunks of meat, hiding the cache from the wolves and other ravens, to assure a larger take, than if they simply stayed at the carcass and ate. Lions occasionally lose a kill to hyenas, so the rule seems to be, if you can accomplish it without too much risk, sometimes by sheer force of numbers or overwhelming size or strength disparity, it's often easier to steal someone else's prey than to secure your own, particularly when prey is scarce, and your stomach is complaining.