In the US, there are two eagle species – the bald eagle and the golden eagle. These majestic birds are among the most magnificent in North America. It is very easy to tell these two species apart, but some may find it more difficult to determine whether an eagle is a male or a female.
Seeing an eagle soaring overhead can be an amazing sight. Both the males and the females are truly astonishing birds.
Though they do have their differences, it is together that they are most remarkable. With their differing strengths, they make a truly excellent pair.
The Difference Between Male and Female Eagles
To tell the difference between male and female eagles, we cannot rely on their plumage alone. We must also look at their size and behavior. Even when we do think about these things, it is still not always easy to discern whether we are looking at a male or female bird.
The Appearance of Male Eagles and Female Eagles
Unfortunately, the appearance of the body shape and plumage of the birds does not give us clues as to the gender of the particular bird we are looking at. This is because the plumage of both sexes is identical for both bald eagles and golden eagles.
Bald Eagle
American Bald eagles, Haliaeetus leucocephalus, live in and around temperate forests and areas near large bodies of open water with an abundant food supply and old-growth trees for nesting.
Both the males and the females have an evenly dark brown body, with a striking white head (that gives this eagle its name) and a white tail. Their tails are moderately long and slightly wedge-shaped.
Golden Eagle
The golden eagle, Aquila chrysaetos, is the second species of eagle found in North America. This is the most widespread of any eagle species and is found not only in North America but in many locations across the northern hemisphere.
The golden eagle prefers hunting in open or semi-open areas and seeks them out year-round.
Both male and female adult birds are mostly dark brown, with some grey on the inner wing and tail, and a paler, typically golden color on the back of the crown and the nape of their necks.
As you can see, the body shape and plumage of both types of eagles are the same whether they are male or female. So we have to seek out other differences between the genders if we want to tell them apart.
Size Differences Between the Male Eagle and Female Eagle
In both bald eagles and golden eagles, the main way to tell the two sexes apart visually is by their size. In both species (as in many birds of prey species) the females are larger than the males.
Bald Eagle Size Differences
Bald eagle females are about 25 percent larger than males. This kind of discrepancy between the appearance of the sexes is called sexual dimorphism.
The length, weight, and wingspan of these birds vary considerably depending on where they are found. But in all regions, the females are, on average, still larger and heavier than the males by roughly this percentage.
Males tend to have a wingspan of up to around 6ft, while females can have a wingspan of around 8ft. Females tend to weigh 5-10 lbs more than males. The females also have a larger back-facing talon and a larger beak.
Golden Eagle Size Differences
The wingspan of golden eagles is the fifth largest among living eagle species. As with bald eagles, the females are larger than the males.
The size differences between the sexes are more significant in larger subspecies of this bird. American golden eagles are typically somewhat smaller than the large Eurasian species but the females are still larger and heavier than the males.
The problem is that if you see an eagle on its own, it can be difficult to gauge its size – especially if it is far away and you are not sure of the distance. So while there is a marked difference between the size of male and female eagles, you might not be able to tell this without seeing a male and a female bird side by side.
Why Are Female Eagles Larger Than Males?
Female bald eagles are larger because they are the ones who have to sit on the eggs and protect their young. Their larger size makes it easier for them to provide the requisite body heat for the eggs and chicks.
Their larger size also helps the females protect the chicks from predation and to fend off attacks.
The smaller size of the males makes them more agile and capable hunters. They need to fly, often over long distances, and swoop down on their prey, to feed not only themselves but also to provide for the females and chicks. So their smaller size means that they need to expend less energy in doing so.
Are Male Eagles Stronger Than Females?
The females are larger and heavier with larger beaks and talons, and as a result, are the stronger of the sexes. The females need to be stronger than the males to protect their nests.
However, the males are also strong and have an amazing capacity to carry prey, and also a remarkable gripping strength in their talons.
The Behavior of Male Eagles and Female Eagles
Aside from size, the other way to distinguish male eagles and female eagles is to observe how they behave. There are differences in the way that males and females behave.
One behavioral difference is that it is the larger females who will sit in the nest and protect the eggs. When protecting a nest, the females will tend to be the more aggressive and territorial of the genders.
The smaller males are more adapted to their task of being the primary hunters – seeking out prey for the baby birds in the nest as well as for the female and themselves. They will be seen hunting a little more frequently than the females, especially during the breeding season.
Vocal Differences Between the Male Eagle and Female Eagle
One other way to tell the difference between male and female eagles is by their voices. However, the differences are not distinguishable by the human ear and so special equipment is required to spot the subtle differences between the two.
With equipment, however, scientists and conservationists can determine whether an eagle is male or female by listening to their calls. The female birds have calls that are slightly lower in pitch than the males.
Do Male and Female Eagles Mate for Life?
With their difference, male and female eagles are each adapted to different tasks. They make a good team together. One of the interesting things about male and female eagles is that once they find a partner, they tend to be monogamous for life.
Sometimes, repeated failures at breeding will lead to separation. And some may find new mates if their partner dies. But some eagles won’t even find a new partner if their mate dies, and will remain alone rather than look for a replacement.