Bald Eagles
Dr. Hardisky and Mx. Lew | Fundamentals of Science
Basic information
The bald eagle is native to almost all of North America. (“Bald” in this case means "white headed.")
Its Latin name is Haliaeetus leucocephalus, and it is the national bird of the United States and appears in many symbols, such as the crest of the Presidential Seal or the Great Seal of the United States (below).
Crest of the Great Seal of the United States.
History of bald eagles in the US: From common to endangered to recovered
Around 1700, the estimated population of bald eagles was more than 300,000. During this period, the species was considered common.
By the 1950s, there were only 412 nesting pairs of bald eagles in the 48 contiguous states of the United States. By the late 1970s, there were no more than three nesting pairs in Pennsylvania. During this period, bald eagles were considered endangered, and were placed on the endangered species list in 1967. Many protections were put in place to protect bald eagles and their habitat.
Today, there are more than 100,000 bald eagles in the wild. Pennsylvania has more than 300 nests. Bald eagles were removed from the endangered list in 1995; they are now considered a recovered species.
Bald eagles typically make their nests as a pair. The nest can be up to six feet wide, and eagles usually build their nests in the tallest tree they can find.
Where are bald eagle nests located?
Examine the map below to see where bald eagles nests have been recorded in Pennsylvania.
- Zoom in on the map to explore a part of Pennsylvania that you are interested in. (For example: Philadelphia.)
- Click on the pins to see what data is recorded about these nests.
- Look at the locations of the pins -- can you identify a pattern? Why are the eagles building the nests where they are?
Bald eagles and wind energy in Pennsylvania -- link to sandbox map: https://arcg.is/Xa4m
Threats to bald eagles
- Pesticides (ingested via prey)
- Lead (ingested via prey)
- Hunting
- Wind turbines
To examine a specific threat to bald eagles, look at a wind turbine located along the Susquehanna River.
Bald eagles and wind energy in Pennsylvania-Public. Link to sandbox map: https://arcg.is/Xa4m
- What output does the wind turbine generate?
- Eagles need about a 5-mile radius to forage. Look at the radius marked around the turbine -- how many active nests are in this area?
- Where might a turbine be placed to avoid being so close to eagles' nests?
