With its white head, golden eyes, and fierce stare, the bald eagle looks like a loner. But America's national bird has a softer side. Bald eagles are famous for pairing up with one partner and sticking together year after year. Is that reputation deserved?
Here's the short answer: mostly, yes. Bald eagles have high mate fidelity and generally mate for life. But it isn't an absolute rule. If one partner dies or disappears, the survivor will choose a new mate. And a pair that keeps failing to raise chicks may split up and look for new partners.
A Daring Courtship Dance
Bald eagles reach breeding age at around four or five years old, and they often return to the area where they were born. Courtship is a spectacular show, with elaborate calls and dramatic flight displays by the males.
The most breathtaking move is the cartwheel. The pair flies high, locks talons, and free-falls together, separating just before they hit the ground. Their flights also include swoops and chases. A mature pair typically defends a territory of about two-thirds of a mile to a mile and a quarter along the water.
Home Sweet Gigantic Home
Bald eagle couples are master builders. Their nest is the largest of any bird in North America. Built of branches, usually in big trees near water, it's often used year after year, with new material added each season.
Over time, nests can grow to about 13 feet deep, 8 feet across, and weigh around a ton. One Florida nest found in 1963 measured about 20 feet deep and 9.5 feet across, and weighed about 3 tons, the largest tree nest ever recorded for any animal. Most nests last under five years before storms or their own weight bring them down, but one in the Midwest was used for at least 34 years.
Bald eagles are early nesters. Building or repairing often starts by mid-February, and eggs are frequently laid in late February, sometimes in deep snow. The young fly from the nest by late June or early July. The adults defend it fiercely and have even been seen knocking a black bear out of a tree when it tried to climb toward their chicks.
A Comeback Story
Not long ago, these loyal couples were in serious trouble. In the mid-20th century, the pesticide DDT made eagle eggshells so thin that many cracked under the weight of a brooding parent. By the 1950s, there were only 412 nesting pairs left in the lower 48 states.
Protections, including a ban on hunting bald eagles and a ban on DDT, turned things around. The bald eagle was upgraded from endangered to threatened in 1995 and removed from the list altogether in 2007.
Eagle Myths and Milestones
You may have heard that Benjamin Franklin wanted the wild turkey as the national bird. There's no evidence he ever publicly said so. He did criticize the bald eagle's behavior in a 1784 letter to his daughter, but that letter was really poking fun at a society he disliked.
In the wild, bald eagles live around 20 years on average, and the oldest confirmed one reached 38. That's a long time to share a nest. So the next time you spot a pair of eagles perched side by side, there's a good chance they've been partners for years.
