The direct answer to what an eagle’s nest is called is an aerie, sometimes spelled eyrie. This massive, highly engineered platform is built for permanence and repeated use by the powerful birds. This grand scale and enduring nature distinguish the aerie from the temporary, smaller nests of most other bird species.
The Official Terminology
The term “aerie” refers specifically to the nest of a bird of prey, particularly an eagle, built on a cliff or other great height. Its origins trace back through Old French to the Medieval Latin term area, which generally meant a flat, open space or a nesting place. The spelling “eyrie” is a common variant that gained popularity due to a mistaken association with the Middle English word for “egg.”
While the term is most closely associated with the nests of species like the Bald Eagle, it can also be correctly applied to the high-perched nests of other large raptors, such as hawks or falcons. Unlike the simple, seasonal cup nests of songbirds, an aerie is a robust, semi-permanent fortress designed to withstand years of weather and use.
Scale, Materials, and Construction
The sheer size of an aerie is what makes it a marvel of avian architecture, often growing larger with each nesting season. Eagles construct the outer framework using large, interlocked sticks and tree branches, sometimes incorporating bones or antlers found in the territory. The diameter of a typical Bald Eagle aerie ranges from four to five feet, with a depth of two to four feet upon initial construction.
To create a comfortable and insulated cradle for their young, the eagles line the inner bowl with softer materials. These include interwoven grasses, moss, plant stalks, and even sod or seaweed, depending on the local environment. Because the breeding pair adds fresh material to the structure every year, the nests continuously expand in size and weight over time.
This annual construction process results in structures that can become enormous, with common aeries weighing up to 2,000 pounds. One of the largest documented nests, located in Ohio, reached a width of nearly nine feet and a depth of 20 feet, with an estimated weight of three tons. The stability of the aerie depends on its foundation, requiring eagles to select sites that can physically support the increasing mass.
Site Selection and Perpetual Use
Eagles are highly selective in choosing a location for their aerie, prioritizing sites that offer both structural support and ecological advantage. In forested areas, they often choose the tallest, most robust trees, such as mature pines or hardwoods, that have strong horizontal limbs capable of bearing the immense weight. Nests are typically situated high in the canopy, often between 50 and 125 feet above the ground, or on remote cliff ledges and rock promontories.
These elevated, inaccessible locations serve as excellent predator defense, keeping eggs and hatchlings safe from mammalian climbers. The height also provides the adult birds with a clear, unobstructed view of their surrounding territory and nearby foraging grounds, which are usually large bodies of water. Eagles often maintain several alternate nests within their defended territory, which they may rotate through in different years.
The most notable behavior regarding aeries is the species’ strong site fidelity, where eagles return to and reuse the same nesting location annually. Breeding pairs will continuously maintain and build upon the same aerie for decades. This multigenerational use of a single structure is a testament to the durability and strategic placement of the aerie, making it a permanent fixture in the landscape.