They’re handsome, they’re regal and they’re superbly efficient hunters. Bald eagles are one of the most widespread and easily recognizable birds in North America. But how much do you really know about them? There are more to these majestic raptors than meets the (eagle) eye!
In recognition of National American Bald Eagle Day in the US (June 20), here are nine facts about bald eagles that may surprise you!
1. They have amazing eyesight
A human with perfect eyesight has 20/20 vision. Bald eagles can have 20/4 or 20/5 vision, meaning they can see four or five times farther than the average person. A bald eagle can spot prey the size of a rabbit three miles away! Eagle eyes are so huge they fill most of its skull. They also have a 340-degree field of view (compared to our measly 180 degrees) and have both monocular and binocular vision. This allows them to use each eye individually or together!
2. They mate for life
Bald eagles do not have commitment issues. Once the females have chosen their mate, they’re usually together for life. There are several courtship rituals they may use to test their potential mate, but the coolest is the cartwheel courtship flight, aka the death spiral! During this spectacular ritual they grasp each other’s talons in flight and somersault toward the earth. Doesn’t human dating seem less scary now?
3. They build enormous nests
Once they form a bond, the eagle pair will build a nest together, returning to the same one year after year. Each year they return they renovate the nest, making it larger. An average bald eagle nest is about 5-6 feet (1.5-1.8 metres) in diameter, and 2-4 feet (0.6-1.2 metres) tall, making them the largest nests of all North American birds. The largest bald eagle nest on record was in Florida. It was almost 10 feet (3 metres) wide, 20 feet (6 metres) deep, and weighed almost 3 tons!
4. They don’t need to eat every day
Bald eagles need about 0.5 to 1 lb. of food each day, but they don’t need to actually ingest that much food every day. Eagles are able to store up to two pounds of food in their crop, an expandable part of their esophagus where they can store and soften food. This means if there’s a shortage of prey, eagles can survive off the extra food in their crop for a day or two.
5. They’re mostly feathers
Considering their massive wingspan (6-7.5 feet or 1.8-2.3 metres), bald eagles aren’t very heavy. They only weigh about 10-14 pounds, much of which comes from their plumage. They have about 7,200 feathers, which weigh about twice as much as their entire skeleton!
6. They aren’t bald!
Bald eagles are covered in thousands of feathers, so they’re far from bald. There’s ongoing debate over the exact origins of the bird’s misleading name, but it appears to be derived from a centuries-old word for white. Bald eagles don’t get that iconic white head and tail until they’re four to five years old.
7. They sound different in the movies
When we think of the sound a bald eagle makes, we imagine a loud, piercing screech that echoes far and wide, which is nothing like their actual vocalization. Hollywood has decided that the actual wimpy twitter of this American icon isn’t cool enough for the movies, and often switch it for the call of the red-tailed hawk.
8. They’re resilient…
While bald eagles have never been in serious trouble on the BC coast, they struggled in many other parts of North America. The first big hit they took was in the mid-19th century, when over-hunting and habitat loss impacted bald eagles and many other bird species.
The second big hit was the use of the pesticide DDT, which became popular in the 1940s. It was used until 1973 in Canada, until 1972 in the US. DDT impacted bald eagles and other birds of prey by infiltrating the food chain, causing them to lay eggs with thin shells that would easily break. Many bald eagle populations crashed.
Banning the use of DDT allowed for a successful recovery for eagles and other birds of prey. Bald eagles were taken off the US endangered species list in 2007, and there are now more than 11,000 nesting pairs in the lower 48 states. BC has an estimated 20 000 bald eagles, second only to Alaska.
9. …but facing another threat
Bald eagles triumphed over the DDT crisis, but they’re still impacted by human activity—specifically hunting. New research shows that many bald eagles are suffering from lead poisoning from ammunition, especially when used to hunt big game. Some hunters leave behind some or all of an animal they’ve shot, a perfect meal for a scavenging eagle. Unfortunately, the eagles often ingest some of this lead ammunition, which often leads to fatal lead poisoning.
In a study of 1,210 bald and golden eagles across 38 US states, 47% had chronic lead poisoning. There have been reported cases in Canada as well, namely in Saskatchewan. Hunters are urged to switch from lead-based ammunition to copper or steel, and to be mindful not just about what they take, but what they leave behind.
Join us on a tour and see a bald eagle for yourself! To book a tour give us a call or book online!
Blog written by Eagle Wing naturalist Lili Wilson.
Published June 18, 2022