Bald Eagles

As we salute our country this month, let’s explore 17 interesting facts about our national bird! 

From Fact Animal:

1. Bald eagles are not actually bald

Despite their name, bald eagles have white, well feathered heads. The word bald once meant ‘white-haired’ and this was the name given to the eagle. Young bald eagles often don’t have white feathers on their head either, they are mostly brown. They develop these from around 5-6 years old.

2. They form a species pair with the white-tailed eagle 

A ‘species pair’ means two species are so similar in appearance and other features that the boundaries between them are often unclear. While roughly the same size and appearance, the white-tailed eagle is thought to have a somewhat paler brown body plumage and inhabits Eurasia, rather than North America. The pair are thought to have diverged from other sea eagles.

3. They have high pitch, rather underwhelming calls

They have a high pitch giggle-scream, rather than an impressive powerful scream that might be the expectation of a bird of the size and power of the bald eagle. Their rather underwhelming call has historically been dubbed over in some TV shows to make it sound more impressive!

When in groups, they emit these surprisingly high-pitched calls to one another and it is believed these vocalizations are a form of transferal of knowledge regarding the area and abundance of prey.

4. A bald eagle’s wingspan can reach 8ft!

Eagles are generally larger in colder environments, which corresponds with Bergmann’s rule – which is that species are generally smaller closer to the equator. This means the largest bald eagles are generally found in Alaska, and can weigh as much as 7kg with wingspans of 2.4m in length.

5. Bald eagles are notorious thieves

The osprey, a much smaller fish-eating raptor, often shares the same habitat as bald eagles. There are many records of bald eagles following osprey and stealing fish they have caught, either straight from the unfortunate bird or when it lands on a nest or perch.

6. They can reach speeds of 99mph when diving

It’s not often that they dive vertically, but they are capable of reaching extremely high speeds when diving for prey!

7. Bald eagles have vision 4-5 times better than humans

Like most birds of prey, the bald eagle has excellent vision, with sharper vision, a wider field of vision and they can even see UV light. It’s thought they are able to see a tadpole move at over 100m distance. It uses this exceptional sense to locate prey while flying at speed. Bald eagles also have a see-through eyelid called a nictitating membrane, which they can close to protect and clean their eyes, but still see!

8. They can catch animals as large as Canada geese

Though they prefer fish, bald eagles will also hunt animals as large as geese which can grow up to 1m in size, and even foxes!

9. Bald eagles can swim!

Bald eagles will sometimes try to catch fish that are too large to pull out of the water. They will rarely let go of prey once they have gripped onto it. Occasionally they will not be able to pull the fish out of water and will subsequently swim to shore with their catch. They use their wings to perform a breaststroke of sorts! It’s a myth that their talons get ‘locked’, they just refuse to let go!

10. Their nests can measure over 2.5m in diameter!

Bald eagles have some of the largest nests of any North American bird, occasionally measuring over 8ft in diameter and 13ft deep. According to the Guiness World Records, the bald eagle also has the largest nest ever discovered near St Petersburg, Florida in the US in 1963. The nest measured 9 ft 6 in wide and 20 ft deep and weighed more than 4,409 lb.  The size of this eagle and nest size requirements mean that they are very particular when it comes to choosing a nest site.

By far the majority of bald eagle nests are found in large, living tall trees which have strong, thick branches to support the mass of the nest as well as the birds themselves. The nests comprise of hundreds of smaller branches and twigs, often with larger branches around the edge. They usually lay between 1 to 3 eggs with two hatchlings most often surviving up to fledgling stage. Fledged chicks leave the nest at around 10 weeks but will still be cared for by their parents for just over a month.

11. They will sometimes nest on large electricity towers or pylons

Where few nesting sites are available, bald eagles will sometimes use manmade structures as nesting sites.

12. The oldest nest on record was used for over 30 years

If well-built in an ideal tree, bald eagle nests can last for many years. One such nest lasted for 34 years before the tree in which it was built was blown down.

13. Bald eagle chicks will cling onto and move sticks within their nests

Chicks develop the muscles in their feet and legs by playing with the twigs and sticks in their nests and even playing tug of war with their siblings.

14. Immature eagles live a nomadic existence until they find a mate

Once young bald eagles have left their parents, they spend much of their time flying across large ranges, seemingly learning about the different habitats that occur in that range.

15. The bald eagle closely resembles the African fish eagle

Though they are found on different continents, both eagles bare remarkable similarities. Both occupy a similar ecological niche and have similar coloration. However the African fish eagle is somewhat smaller, is a lighter brown color and has a black tip to its beak.

16. One of the founding fathers of the USA, Benjamin Franklin, would have preferred the wild turkey as the national bird

People often wrongly believed that bald eagles were cowardly animals as well as prolific thieves of other birds. Even Benjamin Franklin thought the bald eagle was a poor choice as the national bird.

17. They are an endangered species success story!

In 1963 researchers estimated there were just 400 pairs of bald eagles in the US. Thanks to years of protection and a complete ban on the insecticide ‘DDT’, there are now more than 300,000 bald eagles in the lower 48 states, and the species is no longer endangered. 

SOURCE: FACT ANIMAL