Bald Eagle

Common Name: Bald Eagle, American eagle – The white head feathers convey baldness in contrast to the darker body plumage. Eagle is anglicized from the Latin Aquila.

Scientific Name: Haliaeetus leucocephalus – The generic name is from the Greek hali meaning ‘sea’ and aietos, meaning ‘eagle’ to characterize the riparian habitat of the fish-eating bald eagle. The species name means ‘white head’ in Greek. A white-headed sea-eagle is the intended description.

Potpourri: The resurgence of the bald eagle population from a low of about 500 nesting pairs in the contiguous United States in the second half of the twentieth century to ten times that many today is a promising harbinger for reining in the excesses of our own overpopulation. The seemingly inexorable slide toward extinction of the empyreal symbol of the American experiment was a metaphor for the end of the freedoms that the New World once offered; its restitution offers hope. There is perhaps nothing more inspiring to those who seek nature on the trails than to be able to appreciate the majesty of the bald eagle, as much a preeminent symbol for Native Americans as it is to those of us who later immigrated. As the only eagle that is unique to North America, it is entirely fitting that it was chosen as the symbol for what the newly independent Americans aspired to be: strong and free. The bald eagles have returned to the rivers and lakes of their original, native, home – like a phoenix rising from the ashes. [1]

Accipiters (Latin for hawk) are generally considered to be birds of prey and synonymous with the more loosely defined term raptors. They are assigned to their tree-of-life positions due to their characteristic hooked beaks, curved and grasping talons, and keen vision (eagle-eyed). They include both the bald and golden eagles in addition to hawks, kites and the osprey. The sea eagles are distinguished in a separate genus Haliaeetus (from the Greek hali meaning ‘sea’ and aietos, meaning ‘eagle’) in the family Accipitridae due to their preference for fish as a dietary staple; their habitat along streams and the shores of lakes is a consequence. The closest relative of the bald eagle is the Eurasian white-tailed eagle (H. albicilia); the two parted ways about 15 million years ago as the Atlantic Ocean broadened the separation of the North American from the Eurasian plate. An international team of over 200 researchers recently completed a revision to the avian family tree based on the full genomes of 48 species. In addition to the finding that the ancestor of all birds (the so-called teeth-to-beak transition) lived about 116 million years ago, the study found that the closest relatives to the eagles are the new world vultures. [2] The new world (turkey and black) vultures and the California condor are also sometimes considered raptors even though they eat carrion.   Perhaps this better explains why the bald eagle eats carrion like the vultures and also hunts live prey like the hawks and kites; its refection mostly fish (56 %) but sometimes rodents (14%) and other birds (28%). [3]

The carrion-eating behavior of the bald eagle is typically considered pejorative, a blot on America’s escutcheon. However, it should be noted that the bald eagle is a very large raptor, second only to the California condor in size; it is accordingly at the top of the food chain with no predators other than humans. The consequence of having a large body of about 12 pounds (including 1 pound of feathers and a half pound of bone) is the need to consume a substantial quantity of food and necessitates a wingspan of about 6 feet to provide the needed aerodynamic lift to get its large bulk off the ground. The maneuverability of a drone-sized raptor operating within the physically confining restraints of the eastern forests is limited to mostly open areas, arboreal habitats are only suited for roosts. While the bald eagle can reach speeds of 40 miles per hour in open air and almost 100 miles per hour in a dive, this does not necessarily help in the successful prosecution of predation. However, the Gadarene plunge of a bald eagle directed at any other predator that has successfully concluded a hunt is almost guaranteed to chase it away from its prey. This is undoubtedly a matter of evolutionary survival and logic; why bother to expend all that energy in the likely fruitless enterprise of chasing rabbits when the same result can be achieved vicariously? Rather than condemn the bald eagle for the “cowardly” behavior of carrion eating, we should laud it for its intelligent choice. It is also worth noting that, with the exception of hunters, fishers and some small livestock farmers, all humans who are not vegetarians are also carrion eaters.

The family life of the bald eagle is equally worthy of human emulation and is of particular appeal to those who trend to the conservative side of social perspectives: they are monogamous and normally have two eaglets nurtured to viability in a home that is built to last. Once an eaglet reaches sexual maturity at about five years of age, it advertises its puberty with a change of plumage. Immature eagles have mottled feathers that cover the entire body and head uniformly until molting triggered by hormonal factors engenders the contrasting white-feathered crown and nape of the pubescent adult. With eyes almost as large as a human’s but with vision four times more acute (that would be 20:5), the location of a mate is facilitated by the chiaroscuro effect of the white head in contrast to black body. Mate selection is permanent for the approximate 20 years remaining should both attain average eagle longevity. [4] The couple’s honeymoon enterprise is to build a nest at or near the top of a tall tree that is in close proximity to open water. As a permanent home, the nest is embellished and expanded on a yearly basis to the extent that it can reach Brobdingnagian (Gulliver found giants in addition to Lilliputians) dimensions; the record is 10 feet wide and 20 feet tall weighing about 5,000 pounds. [5] Two to three young eaglets hatch after about a month of incubation in their “McNest “and grow rapidly, fledging at 2 months, reaching full size in 3 months, and departing for a five-year odyssey that culminates in baldness. There is something almost human in the life and times of bald eagles.

The definitive Migratory Bird Treaty Act (16 U.S.C. §§ 703–712), was insufficient to protect important non-migratory species. Due to the transcendent importance of the national emblem and the awareness that their populations were continuing to plummet, the Bald and Golden Eagle Protection Act (16 U.S.C. §§ 668-668c), was enacted in 1940 as a supplemental act to prohibit the “taking” bald eagles, including their parts, nests, or eggs. [6] While restrictive legislation was necessary to save the bald eagle, it was not sufficient; by the 1960’s it was clear that extinction was not only possible but likely. Rachel Carson’s seminal 1962 book Silent Spring provided a possible cause in chapter 8, entitled “And No Birds Sing.” Based on a study of robin fatality that was attributed to eating worms that lived under elm trees sprayed with DDT conducted by Dr. Roy Barker of the Illinois Natural History Survey, she suggested a possibly link between eagle decline and insecticides: “Like the robin, another American bird seems to be on the verge of extinction. This is the national symbol, the eagle. Its populations have dwindled alarmingly with the past decade. The facts suggest that something is at work in the eagle’s environment which has virtually destroyed its ability to reproduce. What this may be is not yet definitely known, but there is some evidence that insecticides are responsible.” Her polemic arguments against the prevailing belief that “nature exists for the convenience of man” were profoundly influential; the Zeitgeist of the environmental movement was the ultimate result and DDT became the prime target, the Environmental Defense Fund its protagonist. [7]

The debate concerning the assignation of DDT as the cause of bird eggshell thinning has been loud, long and sometimes angry.  DDT was originally considered to be a great boon to mankind, so much so that the Swiss scientist Paul Müller was awarded the Nobel Prize in Physiology and Medicine in 1948 for discovering its insecticidal properties. It was used extensively in war-ravaged Europe and Asia to prevent typhus, malaria and dengue fever epidemics. The widespread use of DDT was preceded by a great deal of research on its effects by the United States Government and other institutions including universities and the agrochemical industry – it is a toxin after all. Initial tests, such as those by the Sanitary Corps of the U. S. Army which focused on the efficacy of chlorinated hydrocarbons in the eradication of insect pests such as head lice, concluded that DDT was among the best treatments due primarily to the fact that it persisted for long periods of time which would provide better pest management outcomes. This became the argument of the economic entomologists. It is a very effective insecticide; however, it is also toxic to many marine animals, notably fish.  DDT is an organochloride that readily breaks down into DDE which is a fat-soluble compound that builds up in body fat; it has a half-life of about ten years in human body tissue.  It is especially problematic to raptors like bald eagles that eat copious quantities of fish infested with DDT/DDE. [8] This was Rachel Carson’s thesis, which eventually led to the precipitous ban (with some public health exceptions) of DDT in the United States by the EPA in 1972, and by most other countries by the end of the 20th Century. In 2004, the Stockholm Convention (now ratified by 170 countries) established what would seem to be a reasonable middle ground:  DDT is “restricted for disease vector control.” [9] Whether or not DDT elimination played a significant role in the resurgence of bald eagles will likely never be fully resolved; regardless, it was a part of the change in emphasis toward environmental sustainment that clearly did have that desired effect.  The need for environmental protection that was first evinced by Teddy Roosevelt at the beginning of the 20th Century was made manifest by Rachel Carson at its middle; the century’s end marked a new beginning in the resurrection of the bald eagle; on 28 June 2007, it was removed from the federal list of threatened and endangered species. [10]

The bald eagle was chosen as the cynosure of the Great Seal of the United States by the Continental Congress on 20 June 1782. The symbolic importance of the seal to the idea of national sovereignty is manifest in its history; a committee composed of Benjamin Franklin, Thomas Jefferson and John Adams was appointed to submit a design on the 4th of July 1776, the same day that the Declaration of Independence was signed. The careful scrutiny that the seal design received resulted in six years of deliberation that culminated in the final selection: a bald eagle with a 13-stripe escutcheon clutching 13 arrows to symbolize war and an olive branch to symbolize peace beneath a 13-star constellation in the firmament to symbolize the rise of a new sovereign nation. [11] Paradoxically, the bald eagle, though central to the design, was not included in any preliminary drawings made over the six-year hiatus. It was only added at the very end by Charles Thompson, the Secretary of the Congress who was given all of the previous designs to propose a final version. While the reasons for his choice will never be known, his background as a Latin Instructor at Philadelphia Academy may provide a clue: the eagle has a long, and Latin, history. [12]

The eagle figures prominently in the history of western civilization as a symbol of power and authority. In Greek Mythology, an eagle named Aetos Dios was a companion and messenger to Zeus, the chief deity of their pantheon, immortalized in the constellation Aquila. That the eagle became the companion of Jupiter in the Roman version of theogony is quite likely the reason that the Roman legions chose the eagle, which won out over the boar, the Minotaur, the wolf and the horse, as the symbol borne atop their battle standard. After Rome divided and the Eastern Empire succumbed to the onslaughts of the gothic tribes in the 5th Century, the Western Empire became Byzantium, the bastion of Christianity. The Byzantine emperor adopted the double-headed eagle to symbolically represent the power of the state in matters both secular and religious. The double-headed eagle became the symbol of both the Holy Roman Empire (which Voltaire quipped was neither holy, nor Roman, nor and empire) and the Russian Empire, which considered itself “the third Rome” after Ivan the Great married Princess Zoe Paleologa, a Byzantine princess and niece of the last Byzantine emperor, Constantine XI. [13] And last but not least, the Eagle is the symbol of John the Evangelist and figures prominently as one of the beasts in the Book of Revelation. It is no wonder, really, why Thompson selected the eagle and that Congress, after six years and numerous attempts, voted in favor its centrality as a symbol to the newly united states that now became the United States of America. He had empires of eagles to draw on.

It is widely alleged that Ben Franklin favored the turkey as the national symbol. The calumny against the eagle as symbol is based on the documented opinion written by Franklin in a letter to his daughter Sarah Bache from Paris, France in 1784. He castigated the louche character of the eagle, a “bird of bad moral character” as “too lazy to fish for himself” citing that when a “diligent bird has at length taken a fish” then the “Bald Eagle pursues him and takes it from him.” However, this letter had nothing to do with the eagle of the Great Seal, but rather with the symbol of the Society of the Cincinnati, a newly formed group of served revolutionary war officers. Franklin generally abhorred pomp and circumstance and his trenchant wit as evidenced in his Poor Richard’s Almanac aphorisms, was apparent here. Noting that the Cincinnati eagle looked more like a turkey, he went on, in the same letter, to extol its virtues. In noting that the turkey is a “much more respectable bird” his sarcasm becomes evident with the notion that this “bird of courage … would not hesitate to hesitate to attack a Grenadier of the British Guards who should presume to invade his farmyard with a red coat on.”  [14]

References:

1. https://defenders.org/bald-eagle/basic-facts
2. Lewin, S “A Genetic Guide to Birds” Scientific American, April 2015 Vol 312 Issue 4.
3. Stalmaster, M.  The Bald Eagle. Universe Books, New York, 1987.
4. http://www.baldeagleinfo.com/
5. https://journeynorth.org/tm/eagle/NestAbout1.html
6. https://www.energy.gov/nepa/downloads/bald-and-golden-eagle-protection-act-16-usc-668-668c-and-related-regulations-50-cfr
7. Carson, R. Silent Spring, Houghton Mifflin Co. Boston, 1962, pp 103-127.
8. Davis F. Banned. A History of Pesticides and the Science of Technology, Yale University Press, New Haven, Connecticut, 2014.  A source book for the myriad studies of the effects of DDT on the environment.
9. https://www.epa.gov/ingredients-used-pesticide-products/ddt-brief-history-and-status
10. https://ecos.fws.gov/ecp0/profile/speciesProfile?spcode=B008
11. U. S. Department of State Bureau of Public Affairs. The Great Seal of the United States. Available at https://www.state.gov/documents/organization/27807.pdf
12. Patterson, R. and Dougall R. The Eagle and the Shield, A History of the Great Seal of the United States, U. S. Department of State Publication 8900 Released 1978, pp 92-102.
13. Dmytryshyn, B. A History of Russia, Prentice-Hall, New Jersey, 1977. pp 148 – 149.
14. Brands, H. The First American. The Life and Times of Benjamin Franklin. Doubleday, New York, 2000 pp 668 – 670.