Eagle on Radnor Lake by Shelly Mays courtesy of Tennessean
There are two types of eagles found in the North America, the golden eagle and the bald eagle. While golden eagles are occasionally seen in the eastern US, bald eagles are far more frequent east of the Mississippi River. At Radnor Lake, we have started to see bald eagles more frequently starting in 2008. In April of 2008, three bald eagles were spotted and stayed at Radnor until August before moving on. This is also the first documented sighting on eBird.org, a real-time online checklist database used by birders and researchers around the world. Since that initial report there have been 60+ subsequent sightings; 15 sightings reported on eBird in 2016 and several more unreported.
While eagle sightings in the park seem to be on the rise, there are not any nests in the Natural Area. Eagle nests are enormous! While some of the smaller ones are 3-4 feet high and 6 feet wide, some of the larger ones are the size of compact cars. The largest nest on record is in St. Petersburg, FL and is 9.5 feet wide and 20 feet tall, weighing an impressive 3 tons.
Pix by Steve Ward October 2014
There are four ‘groups’ of eagles; the sea eagles, booted eagles, serpent eagles, and harpy eagles. Bald eagles are considered sea eagles and eat primarily fish (about 70-90%). Depending on location, prey availability, and season, they also will eat waterfowl, and just about anything else that is easily caught (even carrion).
The average size of a grown bald eagle ranges from 28-38 inches long with a wingspan of 6-7 feet. Weight varies by region, but falls between 6-14 pounds. Males and females are virtually identical, with females being 20-30% larger. Lifespan can also vary greatly, but the oldest wild eagle, known as Eagle 629-03142, lived to be 38 years old. In captivity, they may live more than 40 years. The adults are easily recognizable by their white heads and tails; however, the juveniles (<4 years old) have brown heads and tails. Upon reaching 4 years of age, they begin to molt in white head and tail feathers. They do have feathers on their head, confusing some as to why they are called bald. It is from the Middle English term ballede, meaning a white spot or blaze of white.
A mature eagle has made Radnor Lake its temporary home. Pix by Shelly Mays courtesy of Tennessean 2014.
In 1782, the bald eagle became the emblem of the United States. The wild populations at this time until the population crash in the 1950’s-70’s is unknown, however there were no known successful nests in Tennessee from 1961 until 1983. The population decline was largely attributed to the pesticide DDT. Congress had previously passed the Bald Eagle Protection Act in 1940 and amended it to include golden eagles in 1962, making it the Bald and Golden Eagle Protection Act. This offered some protection, but the most traction for recovery happened in 1978 with their listing under the Endangered Species Act of 1973. Since 1983, the Tennessee bald eagle nesting population has been on the increase. If the trend continues, we are set for over 200 nesting pairs in Tennessee and 250,000 breeding individuals in North America.
While the bald eagles are no longer listed as endangered or threatened, they are still protected under the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act. These prohibit the take, transport, sale, barter, trade, import and export, and possessions of eagles (alive or dead), their parts, nests, or eggs.
The work “take” means to pursue, shoot, shoot at, poison, wound, kill, capture, trap, collect, molest, or disturb. The primary purpose of a Class II Natural Area like Radnor Lake is the protection on the natural resources. This underscores the importance of staying on the trails in order to reduce human impact in the Natural Area.
While we need to keep our distance from the visiting bald eagles on the lake, there are places from the trails to view them. One of the favorite spots for our visiting eagles is the large point in the middle of the lake. When they are in this area the best places to view are from Otter Creek Rd. directly opposite the point and from the Lake Trail observation deck. You will still need binoculars to see them in detail. There is an opportunity to view this amazing species much closer. Radnor Lake now has a captive, non-releasable bald eagle at the Barbara J. Mapp Aviary Education Center, open to the public Wednesday mornings 7am-1pm and Saturday afternoons 1pm-sunset.
For more information about the Barbara J. Mapp Aviary Education Center
If you want to learn more about bald eagles, please visit: