Bald eagles are renowned for constructing some of the largest and most impressive nests of any bird in North America. Both the male and female participate in nest building, which is an essential part of their pair bonding and continues throughout their lives as they often reuse and add to their nests year after year.
Here’s a breakdown of how a bald eagle makes its nest:
Location, Location, Location:
- Bald eagles typically choose nesting sites near large bodies of water such as coasts, rivers, and lakes, where food is readily available.
- They prefer to build their nests in tall, sturdy trees that offer a clear view of the surrounding area, providing easy flight access and a good vantage point for spotting prey and potential threats.
- These trees are often among the tallest in the vicinity, sometimes referred to as “super-canopy” trees, with strong branches capable of supporting a massive structure.
- While trees are the most common site, in areas where trees are scarce, they may also nest on cliffs or rock formations.
Materials and Construction:
- The primary building material for a bald eagle nest is large sticks and branches. Both eagles collect these, breaking them off trees or picking them up from the ground. They can carry surprisingly large and heavy sticks in their talons.
- The base of the nest is constructed by weaving together these large sticks to create a sturdy platform, usually in a major crotch of the tree near the trunk.
- As the nest takes shape, they fill in the gaps and create a more solid structure by adding a variety of softer materials. These can include moss, grasses, plant stalks, seaweed, sod, and even cornstalks.
- The central part of the nest, known as the “bole” or nest cup where the eggs will be laid, is lined with finer, softer materials for insulation and cushioning. This lining can consist of lichens, softer woody materials, feathers (including their own down), and sometimes fresh sprigs of greenery, which some believe may help deter parasites.
- The female eagle often takes the lead in arranging and weaving the materials within the nest structure, particularly in shaping the nest cup, while the male brings in the bulk of the sticks.
Time Lapse Video of Eagles Building Nest
This time lapse video helps give us a better understanding of how bald eagles build their nests, one stick at a time.
Size and Longevity:
- Bald eagle nests are massive, typically measuring 5 to 6 feet in diameter and 2 to 4 feet deep. However, with continuous use and additions over many years, they can grow to astonishing sizes.
- Some historical nests have been recorded at over 13 feet deep and 8 feet wide, weighing over a ton. These colossal nests are a testament to the pair’s ongoing efforts.
- The consistent addition of material means that nests can become quite heavy, and occasionally, the sheer weight combined with weather conditions can cause the supporting tree or the nest itself to collapse.
- Bald eagles exhibit strong nest site fidelity and will often return to the same nest or an alternate nest within their territory year after year, continuously maintaining and expanding it.
The process of building and maintaining their nest is a significant investment of time and energy for bald eagles, highlighting the importance of a secure and well-built structure for successfully raising their young.