The Bald Eagle is one of North America’s most recognizable birds, yet the size of its nest often surprises people. These raptors construct massive structures that are among the largest bird nests in the world. The sheer scale of these homes reflects the long-term commitment of the eagles that build them. Since the nest functions as a generational home used year after year, its size increases continuously.
The Incredible Scale of Bald Eagle Nests
Bald Eagles build the largest nests of any bird species in North America, often referred to as an aerie. A typical nest measures between five and six feet in diameter and two to four feet deep. These dimensions mean the average nest is larger than a household bathtub, providing a spacious platform for the eagles and their young.
An average established nest weighs around 1,000 pounds, or half a ton. This immense weight results from the eagles adding material each year, a process known as accretion. Nests used for decades have reached monumental proportions, testing the structural limits of supporting trees. The largest recorded nest, found in St. Petersburg, Florida, was 20 feet deep, 9.5 feet wide, and estimated to weigh nearly 6,000 pounds.
Construction and Lifespan
Nest construction begins with a foundation of large sticks and branches, which the birds interweave to create a sturdy, circular platform. Both the male and female participate; the male gathers the bulk of the larger sticks, while the female focuses on arranging and weaving the materials. They carry sticks up to three feet long in their talons and beaks, and the initial structure can take up to three months to complete.
The eagles fill the stick framework gaps with softer materials to create a solid structure and a comfortable inner cup for the eggs. This lining includes grasses, moss, sod, lichens, and downy feathers for insulation and cushioning. The pair reuses and reinforces the same aerie every breeding season, with some sites used continuously for over 30 years. This longevity and the annual addition of new material cause the nest to grow continuously in depth and weight.
Preferred Nesting Habitats
Bald Eagles are selective when choosing a nesting site, prioritizing security and easy access to food. They typically select tall, mature trees, often conifers, that protrude above the surrounding forest canopy, known as a “super-canopy” tree. This height provides a commanding view for spotting prey and potential threats, and allows for easy flight access to the nest.
The selected tree must possess limbs sturdy enough to support the nest’s enormous weight. Nesting sites are almost always located near large bodies of open water, such as coastlines, rivers, or lakes, ensuring an abundant supply of fish. While old-growth trees are preferred, eagles occasionally use man-made structures like communication towers or build nests on cliff faces where suitable trees are scarce.
Annual Use and Maintenance
Bald Eagles exhibit strong nest site fidelity, returning to the same territory and structure year after year for breeding. Nesting behavior begins one to three months before the female lays eggs, with the pair engaging in maintenance and repair activities. They share the responsibility of bringing new sticks to reinforce the structure and adding fresh, soft lining to the inner nest cup.
This early season work involves clearing debris from the previous year and fixing any damage caused by weather. The male and female work in synchronization, with maintenance becoming more regular as the time for egg-laying approaches.