Bald eagles are one of the most iconic birds in the world. These large, majestic raptors are widespread across North America and northern Mexico and are easy to identify thanks to their white head and tail. Here, we’ll be taking an in-depth look at female Bald eagles.
Like most raptors, female Bald eagles are around 20 to 28% larger than males and weigh over 1kg more (4.2kg vs. 5.3kg in one study). Their rear-facing hallux toe is larger than the male, and the beak is slightly deeper, but aside from that, they’re very similar in appearance. Females generally incubate the eggs more than the male and play the major role in rearing the chicks, but the males contribute, and some duties are shared relatively equally.
Female bald eagle (left) and male on the right - see the size difference
In the vast majority of bird species, the males are usually slightly or substantially larger than the females. But, in raptors, this is reversed, and the females are always larger than the males.
There are a few theories for this; the difference in size might enable females to fight off aggressive males, or allows them to hunt larger prey, meaning the pair can diversify their hunting specialism. But, perhaps the most convincing theory is that their larger size enables the females to defend the nest against predators more effectively.
Bald eagle males and females both play essential roles in rearing the chicks. Pairs last for life, though some may divorce if they fail to raise healthy chicks.
Of course, there is much more to learn about female Bald eagles. Read on to learn more about these iconic raptors!
Perched pair of Bald eagles - female (left) and male (right)
Size is the main difference between male and female Bald eagles. The females are up to 1/3rd (33%) larger than the males. This difference varies regionally - females are more typically 20 to 28% larger than males.
This size difference is evident in the birds’ wingspans, as the female’s wingspan can be 2 feet larger than the male. Female Bald eagles also measure around 35 to 37 inches in length, while males tend to be 30 to 34 inches long.
Side-by-side comparisons should make females relatively easy to tell apart from males on size alone. There are very few visual differences between male and female Bald eagles aside from sheer size.
You can only differentiate male and female Bald eagles by size, with females being somewhat larger
Female Bald eagles are much bigger and heavier than males - their wingspans may be as much as 2ft larger than the males, and they’re over 1kg heavier.
Aside from that, female Bald eagles look the same as males in coloration. They’re predominantly dark brown with bright white heads and tails. It’s impossible to tell male and female Bald eagles apart on coloration alone.
There are two other minor visual differences between male and female Bald eagles:
Bald eagles have three forward-facing talons and one backward-facing talon (the hallux). The backward-facing talon is considerably larger in female Bald eagles. The females also have larger footpads. These are the most efficient ways of sexing Bald eagle chicks.
Female Bald eagle beaks are typically larger and deeper than the males. Combined with more enormous talons, female Bald eagles catch larger prey than the males.
Bald Eagle soaring through the sky
Male and female Bald eagles don’t differ in color, nor do they molt differently as they grow and develop from juveniles into adults.
You couldn’t hope to tell male and female Bald eagles apart on color or plumage alone.
Adult male and female Bald eagles both invariably have white heads, and there are no other differences in color. Female Bald eagles have white heads, the same as the males.
In fact, male and female Bald eagles are pretty much identical in coloration and plumage - the main difference is that females are around 25% bigger than males.
Bald Eagle taking a drink of water from a lake
Female Bald eagles are around 20% to 33% larger than the males. In terms of weight, the females weigh approximately 1kg to 1.4kg more than males (4.2kg vs. 5.3kg in one study).
Female Bald eagles also measure around 35 to 37 inches in length, while males tend to be 30 to 34 inches long. The females’ wingspans can be some 1 to 2ft larger than the males.
The size differences between male and female Bald eagles vary regionally and tend to be more profound at the northern latitudes of their range, e.g., in Canada and Alaska.
Female (left) and male (right) Bald eagles in flight
Bald eagles form strong, monogamous pair bonds that tend to last for life. The yearly divorce rate is around 5 to 15%, depending on the region.
The male and female share many duties when it comes to raising the chicks. The female typically chooses the nesting site, and the male gathers materials while the female assembles the nest. When the eggs are laid, the female incubates them most of the time (around 70 to 90%).
Once the eggs hatch, the female remains at the nest for around 90% of the time. This may be crucial in explaining why the female is larger than the male, as the female becomes very defensive of the nest during this time and her superior size allows her to ward off more predators than the male. However, the males are also fiercely territorial of the nest. Interestingly, females usually chase off females, and males chase off males.
Meanwhile, the male will hunt food for the chicks, which he delivers for the female to tear up and administer to the chicks. This may explain why the female’s beak is deeper and larger than the male’s. After around 2 weeks a month, the female joins the male to hunt prey for the chicks.
Bald Eagles work together to build the nest, with males bringing back the materials and females assembling
Female and male Bald eagle calls are very similar, quite soft, subtle, and whistling. The female may have a slightly lower pitch call than the male.
The female also has a uniquely soft, whistling call that involves repeating a single high-pitched note, which is believed to signal to the male that she is ready for copulation.
Despite the females being larger than the males, it’s still very much the male’s responsibility to court the female. Bald eagle courtship is spectacular and involves the males swooping, chasing, cartwheeling, and barrel rolling through the air. They perform daring fly-bys of the ground and dive towards the ground at incredible speeds.
Male Bald eagles are more agile and fast than females, so they’re often more efficient at hunting. As a result, females can catch bigger prey, but males are more successful when hunting.
Close up portrait of a Bald eagle
Male and female Bald eagles form strong, lifelong pair bonds and share many duties. While a female could feasibly incubate the chicks herself, it’d be extremely difficult to feed them on her own. The male’s role in raising young is essential.
In the first two weeks to a month after hatching, the male hunts prey for the chicks as the female guards the nest. After that, it’s usually necessary for both the male and female to hunt food for the hungry chicks.
Very rarely, a female will join another pair of Bald eagles to assist them in rearing their chicks, but this behavior is poorly understood.
There’s no specific name for a female Bald eagle. Both male and female Bald eagles are referred to simply as “Bald eagles”.
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