As the chill of winter recedes and the promise of spring fills the air across North America, a vital and fascinating chapter in the lives of Bald Eagles begins to unfold: nesting season. From the meticulous construction or refurbishment of their massive stick nests to the patient incubation of eggs and the demanding work of raising their young, this period is crucial for the continuation of this iconic species.

This article explores the intricacies of the Bald Eagle nesting season, exploring the timing, behaviors, and challenges faced by these magnificent birds as they undertake the essential task of bringing new life into the world.

Differing Seasons

The Bald Eagle nesting season varies significantly across the United States due to latitude and climate. The timing of each stage shifts depending on the state’s latitude and climate. Southern states have a much earlier nesting season to avoid the intense heat of late spring and summer, which could be detrimental to eggs and young.

In the northern states and Alaska, there is a later nesting season to coincide with the arrival of warmer weather and increased food availability in the spring and summer months. The shorter summers also compress the breeding cycle. The entire breeding cycle, from courtship and nest building to the fledging of young, can take several months.   

Courting Behaviors

Courtship behaviors can begin several months before egg-laying, sometimes as early as the late fall or winter, depending on the region. This period helps establish or strengthen the pair bond. Bald Eagles engage in spectacular aerial displays that reinforce their bond and demonstrate their fitness. The cartwheel flight is where the pair flies high, locks talons, and tumbles downwards in a spinning cartwheel motion, separating just before hitting the ground.

This dramatic display may also be a territorial behavior. Another display is the rollercoaster flight as one eagle, often the male, soars upwards and then dives steeply, pulling up and repeating the maneuver. 

The courting eagles have other exciting displays. They will chase each other through the sky with impressive speed and agility, and at times may pass sticks to each other in flight, symbolizing their cooperative nature in nest building. During these displays, they may communicate with each other through various calls, which can become more frequent and intense as they get closer to mating. 

Like most other courting birds, paired eagles will spend time perching together, often touching bills, preening each other’s feathers, and engaging in mutual calling. The male may bring food to the female as a gift during this time.

So, Bald Eagle courtship is a spectacular sight, involving intricate aerial displays, vocalizations, and dedicated nest-building activities. The timing of these behaviors varies significantly across the contiguous United States, primarily influenced by latitude and local climate conditions. Generally, courtship and nest-building precede egg-laying by several weeks to months.

Watching Bald Eagles courting is a bird watcher’s dream. Here is our guide to seeing this incredible display, depending on where you are.

• Northeast (e.g., Massachusetts, Maryland): Mid-winter to late winter (approximately December to February). In states like Massachusetts, courtship displays are prominent in mid- to late winter. In areas like Maryland, courtship can begin as early as December.
  
• Southeast (e.g., Florida, Louisiana, and other Gulf Coast states): Fall to early winter (approximately September/October to December). Bald Eagles in the Southeast have an earlier breeding schedule. They often return to their nesting territories in late August or early September. Courtship activities, including reinforcing pair bonds and initial nest work, will commence shortly after. The general nesting season in the Southeast is recognized from October 1st to May 15th.
  
• Midwest (e.g., Ohio, Iowa, Minnesota): Mid-winter (approximately late December through February). Courtship and nest-building activities typically ramp up in January and February. Some dedicated pairs might begin reinforcing bonds and light nest work as early as October, with more intensive courtship behaviors deepening through December and January. Leafless trees during this period can make spotting eagles and their nests easier.
  
• Pacific Northwest (e.g., Washington, Oregon): Fall to early winter (approximately late September to December for initial activities, with further displays into January/February). Resident eagles in this region may begin their breeding cycle, including courtship and re-bonding, upon returning from any migrations in late September or early October. This period involves significant nest rebuilding. Intense territorial defense and associated displays can be observed through November and December. Final nest preparations and continued courtship displays can occur from mid-January through February.
  
• Southwest (e.g., Arizona): Late fall to early winter (approximately December to January). The resident desert nesting Bald Eagles in areas like Arizona have a distinct breeding timeline adapted to the harsh desert environment. Courtship typically begins in December, with nest building or enhancements starting in January. This is notably earlier than populations in northern latitudes.

Nest Building

Bald Eagles exhibit strong nest site fidelity, often returning to the same nest year after year. They may also build alternate nests within their territory. Both males and females participate in building a new nest or refurbishing an existing one. This activity is also considered part of the pair-bonding process. Nest building can begin 1-3 months before egg-laying.

They construct massive nests called aeries from large sticks, lining the nest cup with softer materials such as moss, grass, plant stalks, lichens, seaweed, or downy feathers to insulate the eggs. Nests are typically 4-6 feet in diameter and 2-4 feet deep, and they are usually located in tall, mature trees (often conifers or deciduous trees near water), on cliffs, or occasionally on artificial structures, providing a clear view of the surroundings. The nest needs to be sturdy enough to support the adults and the growing eaglets, and can weigh hundreds of pounds. Eagles continue to add sticks and soft lining to the nest throughout the nesting season and even in the fall and winter, maintaining and enlarging it over its lifespan. 

This can begin 1-3 months before egg-laying. In southern areas, this might start as early as October or November. In the north, it typically begins in late winter or early spring, February-April.

Mating

Mating typically occurs from the time the pair returns to their nesting territory through the egg-laying period, and sometimes even a few months after. Copulation itself takes place on a sturdy branch or within the nest itself, not in flight. The male will approach the female, often with vocalizations and tail swishing, and then land on her back. The female will tilt forward and move her tail to the side, allowing the male to align his cloaca (the external opening for reproductive and excretory systems) with hers.

This brief touching of cloacae, known as a ‘cloacal kiss’, allows for the transfer of sperm. A pair may mate several times a day over a period of days, which helps to ensure fertilization. Bald Eagles are typically monogamous and often mate for life. If one mate dies, the surviving eagle will usually find a new partner.

Egg Laying

The timing of egg-laying is most variable.

• Southern U.S. (e.g., Florida, Texas): Egg-laying can begin as early as October to December.
• Mid-latitudes (e.g., California, Arizona, Carolinas): Egg-laying typically occurs from December to February.
• Northern U.S. (e.g., Great Lakes region, Pacific Northwest): Egg-laying usually starts in January to March.
• Alaska: Egg-laying is typically the latest, occurring from late April to May.

Eaglets

Once eggs are laid (usually 1-3, laid a few days apart), incubation lasts for about 35 days. After hatching, eaglets remain in the nest for approximately 10-14 weeks before fledging. Young eagles often remain near the nest and are dependent on their parents for food for several weeks (4-11 weeks) after fledging.   

Feeding Growing Chicks

Estimating the exact amount of food a pair of Bald Eagle chicks needs daily is complex and depends on several factors, including the chicks’ age, size, growth rate, and the availability and type of prey. 

Early Nestling Stage (Weeks 1-3)

During the first few weeks, chicks are small and their food intake is less. Parents feed them small, torn pieces of fish or other prey multiple times a day (1-8 times). The male parent typically provides most of the food during this period.

Rapid Growth Stage (Weeks 4-8)

This is when the chicks experience their most rapid growth, gaining significant weight daily (around 5-5.3 ounces per day). Their appetite increases substantially, and both parents actively hunt and bring food to the nest. By around 8 weeks old, their food consumption is at its peak.

Late Nestling Stage (Weeks 9-12/Fledging)

While still growing, the rate slows down compared to the previous stage, and the chicks are nearly full-grown by this point. Parents continue to provide a significant amount of food as the chicks prepare to fledge.

Studies suggest that adult Bald Eagles typically eat 0.5 to 1 pound (250-550 grams) of food per day, which is about 5-10% of their body weight. Chicks, with their rapid growth, will likely require a proportionally larger amount of food relative to their size, especially during the peak growth phase. 

Final Thoughts

The courting, mating, and nesting process of Bald Eagles is a fascinating and crucial part of their life cycle, typically unfolding over several months. This entire process, from courtship to the fledging of young, is a testament to the strong pair bonds and cooperative nature of Bald Eagles, ensuring the survival of their offspring. Their wide range means that their nesting season is not uniform across the United States and is strongly influenced by geographic location, particularly latitude, which affects temperature, daylight hours, and food availability.

The further south you go, the earlier the nesting season tends to begin. You can find specific breeding season dates for each state on the U.S. Fish & Wildlife Service website. Whether you see these wonderful creatures courting or with their young, or even just exploring their world, it is a privilege and honor to be in their presence.