By Bryan Stevens
Happy Fourth of July to everyone. I thought this week’s column should focus some attention on our national bird, the American bald eagle, which officially became the national emblem in 1782 when the great seal of the United States was adopted.
Despite elevating this native bird to such lofty status, we have not always been kind to the bald eagle. We allowed habitat destruction and toxic pesticides to bring this eagle to the brink of extinction. With some protection, however, the bald eagle rebounded. In fact, the Department of Interior took the eagle off the endangered species list on June 28, 2007.
The bald eagle has been more frequently observed by birders in Northeast Tennessee in recent years. Some of the area lakes in the region are good places to look for Bald Eagles, particularly in the fall and winter. A few lakes even host nesting bald eagles. For instance, this eagle has been documented nesting at Holston Lake in recent years.
I’ve observed bald eagles in Tennessee, South Carolina, Florida and Virginia. My most unusual observation of a wild bald eagle took place on Labor Day many years ago when an adult eagle flew over my grandparents’ home in Limestone Cove in Unicoi County.
North America’s other eagle, the golden eagle, is a very rare visitor to northeast Tennessee. The golden eagle is primarily a bird of the western United States while the bald eagle ranges widely across the United States as well as into Canada and Mexico.
The eagles are incredibly majestic birds and important symbols of the value of natural places and creatures.
The bald eagle (Haliaeetus leucocephalus) is a member of a genus known as Haliaeetus, or sea eagles. There are seven other living species in the genus: the white-bellied sea eagle, Sanford’s sea eagle, African fish eagle, Madagascar fish eagle, Pallas’s fish eagle, white-tailed eagle and Steller’s sea eagle.
The bald eagle, however, is not considered closely related to eagles in the genus Aquila, or “true eagles,” in which the golden eagle is included.
Both male and female adult bald eagles have a blackish-brown back and breast; a white head, neck and tail; and yellow feet and bill. Juvenile bald eagles are a mixture of brown and white and reach full maturity in four to five years.
The female bald eagle is 35 to 37 inches in length, slightly larger than the male, with a wingspan that ranges from 72 to 90 inches. Bald eagles weigh from 10 to 14 pounds.
Despite these impressive characteristics, the bald eagle is dwarfed in comparison to one of its now-extinct relatives. The largest eagle ever to evolve was Haast’s eagle, which once thrived in New Zealand. This eagle was named for the German geologist Julius von Haast, who founded Canterbury Museum at Christchurch in New Zealand. Haast, who died in 1887, was one of the first scientists to study large flightless birds such as the moa family that once roamed New Zealand.
In fact, Haast’s eagle was considered a major predator on the population of New Zealand moas, some of which reached a height of 12 feet tall and a weight of more than 500 pounds. By contrast, female Haast eagles probably reached a weight of 22 to 33 pounds. Males, as is the case with most living eagles, are smaller than females and probably weighed between 20 to 26 pounds. This mega-sized eagle possessed a relatively short wingspan of roughly 8 to 10 feet wide. This wingspan compares to that recorded for large specimens of golden eagle and Steller’s sea eagle. Even the largest of today’s eagles, however, are about 40 percent smaller in body size than the size of Haast’s eagles. Despite their superior size, moas simply lacked any defense against the huge razor-like talons and sharp bill of the Haast’s Eagle.
Here are a few other eagle facts:
— Eagle bones are light because they are hollow. The beak, talons and feathers are made of keratin.
— The Madagascar fish eagle is the most rare eagle on earth, and one of the most rare birds. The current population is estimated at less than 400 individual birds, with perhaps around 120 breeding pairs.
— Bald eagles have 7,000 feathers.
— Wild bald eagles are long-lived birds and may live as long as 30 years. In captivity, however, the oldest documented Bald Eagle lived to be 47 years old.
— Bald eagles can lift as much as four pounds. They feed mainly on fish, but they will take advantage of carrion and scavenge for their meals. They will occasionally also take waterfowl as prey.
— The hunting area of bald eagles varies from 1,700 to 10,000 acres. Home ranges are smaller where food is present in great quantity.
— Bald eagles can fly to an altitude of 10,000 feet. During level flight, they can achieve speeds of about 30 to 35 miles per hour.
— All eagles are renowned for their excellent eyesight.
— Once paired, bald eagles remain together until one dies. Bald eagles lay from one to three eggs. The 35 days of incubation duties are shared by both male and female.
— Today, there are about 10,000 breeding pairs of bald eagles.
I look forward to hearing from readers. Those who wish to ask a question, share an observation or make a comment may reach me at firstname.lastname@example.org.