Bald Eagles vs. Golden Eagles: They Are More Different Than You Think!
With Bald Eagles officially becoming the United States’ national bird in December, I thought it would be a good idea to take a moment and talk about North America’s largest birds of prey. These birds share some characteristics but there are some key differences that highlight the unique natures of these two species.
Many people assume that all Bald Eagles have white heads and tails with a bright banana-colored bill like that ‘murica eagle we’re all familiar with. But the reality is that it takes 4 to 5 years before an eagle will look like that. Golden Eagles similarly have a definitive adult plumage that takes them 4-5 years of molting feathers to acquire. Both eagles will go through several different stages before reaching “adulthood”.
As eagles age we call them juveniles in their first year; immatures or basic I, II, and III in their second, third, and fourth year, respectively; and adults in their fifth year and after. It isn’t until they reach adult plumage that they start nesting (this is in stark contrast to many smaller species like hummingbirds that attain adult plumage and start nesting before their first birthdays).
So how do we tell these two species apart when they aren’t adults?
The first thing to note is that the shape of the two eagle species varies slightly. The most marked difference is the head and bill size. Bald Eagles have proportionally larger heads with significantly more robust bills than Golden Eagles. Although it is subtle, I often refer to Bald Eagles as flying two-by-fours because of the boxy appearance of their long wings. Golden Eagles have more curvature to the trailing edge of their wing, especially near their body where the wings taper inward more than on Bald Eagles.
Both species can have some white in their tails but young Bald Eagles show white markings in the armpits or “axillaries” of their wings that Golden Eagles don’t have. When young Golden Eagles do have white in the wings it is near the outside of the wing on the primary feathers. This difference is important to note because young Bald Eagles have large white patches in the base of their wings where light does not shine through but young Golden Eagles have translucent windows near the end of their wings that are obvious when backlit by the sun. These windows in each wing plus the white patch in the tails of Golden Eagles give us a great identification point for beginners to grab onto: “three points of white”. Juvenile Golden Eagles often show this feature. As both the eagles age, they have intermediate features between their juvenile and adult forms. You can often tell immature birds from first-year or adult birds because they look “messy” with feathers of different lengths or broken patches of white and dark throughout their plumage
Dividing Eagle Territory: Do Bald and Golden Eagles Share Space?
Bald and Golden Eagles overlap in habitat somewhat with both birds frequenting grassland habitats including prairie dog colonies. However, Golden Eagles are more common in foothill and steppe habitats while Bald Eagles are more closely associated with water. Both eagles like to eat carrion (especially in winter) but Bald Eagles are avid fish eaters whereas Golden Eagles tend to avoid seafood. Golden Eagles have been observed hunting animals as large as deer sometimes driving their prey off of cliffs to kill them.
Bald Eagles often steal food from birds like Osprey, this behavior is known as kleptoparasitism. This behavior is one of the reasons that Benjamin Franklin did not think that the Bald Eagle should be our national symbol but instead preferred the noble Wild Turkey to gobble up that role.
Join Me to Improve Your Birding Game
Don’t be dismayed if you still feel a little confused by eagle identification. I sometimes see a distant eagle that I am unable to identify. Misidentification of eagles is sort of baked into our modern culture. Most TV programs and movies choose to play a Red-tailed Hawk call every time an eagle shows up on screen because, well, it sounds more impressive.
If you want to improve your raptor identification, it’s one of my specialties. Come birding with me at the Rocky Mountain Arsenal or on one of my multi-day trips to learn more!