How Much Does An Adult Bald Eagle Weigh?

With its white head, distinctive brown body, and massive wingspan, the bald eagle is an imposing bird of prey and the national symbol of the United States. But just how heavy are these majestic raptors? An adult bald eagle has a substantial weight to support its large frame and enormous wings.

If you’re short on time, here’s a quick answer: The average weight of an adult bald eagle is typically between 8-14 pounds.

Average Weight Range

Males: 8-10 pounds

Male adult Bald Eagles typically weigh between 8 to 10 pounds. These majestic birds are known for their impressive wingspan and powerful build. Despite their large size, they are surprisingly agile in flight, capable of reaching speeds of up to 40 miles per hour.

It is fascinating to see how these magnificent creatures navigate through the skies, effortlessly gliding above treetops and bodies of water.

Females: 10-14 pounds

Female adult Bald Eagles, on the other hand, tend to be slightly larger and weigh between 10 to 14 pounds. The difference in weight between males and females is a result of sexual dimorphism, which is common in many bird species.

In the case of Bald Eagles, females are generally larger and have a more robust physique compared to their male counterparts.

The weight of an adult Bald Eagle is influenced by various factors, including age, diet, and overall health. These birds primarily feed on fish, waterfowl, and small mammals, which provide them with the necessary nutrients to maintain their size and strength.

It’s important to note that weight can vary within the average range, as individual Bald Eagles may have different body compositions.

If you’re interested in learning more about the weight and other fascinating characteristics of Bald Eagles, you can visit the Bald Eagle Information website. This reliable source provides detailed information about these magnificent birds, their habitats, and conservation efforts aimed at protecting their populations.

Factors Affecting Eagle Weight

Several factors can affect the weight of an adult bald eagle. Understanding these factors can give us insights into the variations in weight observed within the species.


The age of an adult bald eagle is one of the primary factors influencing its weight. Younger eagles tend to weigh less than older ones. As eagles mature, their bodies develop and gain more muscle mass, resulting in an increase in weight.

A fully grown adult bald eagle can weigh anywhere between 6 and 14 pounds.


Sex also plays a role in determining the weight of a bald eagle. Females are generally larger and heavier than males. This sexual dimorphism is seen in many bird species, and bald eagles are no exception.

Female bald eagles can weigh up to 14 pounds, while males typically weigh between 6 and 10 pounds.

Geographic Location and Habitat

The geographic location and habitat of an eagle can have an impact on its weight. Bald eagles living in northern regions, where temperatures are colder and prey may be scarce, tend to be heavier. This is because they need to store more fat to survive the harsh conditions and have a better chance of successful hunting.

In contrast, eagles living in warmer regions may have access to a more abundant food supply, resulting in slightly lower weights.

Time of Year

The time of year can also affect the weight of a bald eagle. During the breeding season, eagles may lose weight as they invest energy in courtship, nest-building, and raising their young. On the other hand, in the winter months when food is more abundant, eagles may gain weight to prepare for migration or to endure the colder temperatures.

Weight Changes Over Life

Understanding the weight changes in a bald eagle’s life can provide valuable insights into their growth and development. From hatchlings to adults, these majestic birds undergo significant transformations in size and weight.

Let’s explore the weight changes that occur at different stages of their life.

Hatchlings: 3-4 ounces

When bald eagles hatch, they are incredibly small and fragile. At this stage, they typically weigh around 3-4 ounces (85-113 grams), which is roughly equivalent to the weight of a small apple. These tiny hatchlings heavily rely on their parents for warmth, protection, and nutrition.

Fledglings: 8-14 pounds

As bald eagles grow, they enter the fledgling stage, which marks the beginning of their journey towards independence. Fledglings are around 10-12 weeks old and have developed their flight feathers. During this stage, their weight increases significantly, ranging from 8 to 14 pounds (3.6 to 6.3 kilograms).

This weight gain is crucial for building strength and endurance as they learn to fly and hunt on their own.

Adults: Reach full weight at 5 years old

Once bald eagles reach adulthood, their weight stabilizes and reaches its peak. On average, adult bald eagles weigh between 8 to 14 pounds (3.6 to 6.3 kilograms), with females being slightly larger than males.

It’s important to note that weight can vary depending on factors such as geographic location and prey availability.

At around five years of age, bald eagles reach their full weight and physical maturity. By this point, they have developed their iconic white head and tail feathers, a distinguishing feature of adult bald eagles. These majestic birds continue to thrive and can live up to 20-30 years in the wild.

For more information on bald eagles and their weight changes throughout life, you can visit the Bald Eagle Information website. They provide in-depth details on eagle biology, behavior, and conservation efforts.

Measuring Eagle Weights

When it comes to determining the weight of an adult Bald Eagle, there are several methods that researchers and experts use. These methods allow for accurate measurements while minimizing stress on the birds. Let’s take a closer look at some of the most common techniques:

1. Leg band scales

Leg band scales are one of the most commonly used methods for weighing adult Bald Eagles. This involves attaching a small scale to the bird’s leg band. When the eagle perches on a specially designed scale, its weight can be accurately recorded.

Leg band scales are often used by researchers to monitor the overall health and condition of individual eagles over time.

2. Perch scales

Perch scales are another method used to measure the weight of adult Bald Eagles. These scales are designed to resemble natural perches and are placed strategically in areas where eagles frequent. When an eagle lands on the perch, the scale beneath it records its weight.

This method is particularly useful for studying the weight fluctuations of eagles in their natural habitat.

3. Estimates based on wing chord length

In some cases, experts can estimate the weight of an adult Bald Eagle based on its wing chord length. The wing chord is the distance between the wrist and the tip of the longest primary feather. By comparing the wing chord length to known weight data from previously weighed eagles, researchers can make an educated estimate of an eagle’s weight.

While this method may not be as accurate as the previous ones, it can still provide valuable insights.

It’s important to note that the weight of an adult Bald Eagle can vary depending on various factors, including gender, age, and overall health. On average, male Bald Eagles weigh between 7 and 10 pounds (3.2-4.5 kg), while females tend to be larger, weighing between 10 and 14 pounds (4.5-6.4 kg).

These majestic birds have an impressive wingspan of up to 7 feet (2.1 meters) and can reach speeds of over 30 miles per hour (48 kilometers per hour) when in flight.

If you’re interested in learning more about Bald Eagles and their weight measurements, be sure to check out Audubon’s field guide on Bald Eagles, which provides in-depth information on their physical characteristics and behavior.

Why Weight Matters

When it comes to the majestic bald eagle, weight plays a crucial role in its overall well-being and survival. This article explores the significance of weight in adult bald eagles, focusing on how it indicates their health and fitness, impacts their hunting abilities and success, and influences their mate selection.

Indicates health and fitness

The weight of an adult bald eagle serves as an important indicator of its overall health and fitness. A healthy eagle will have a weight within a certain range that allows it to maintain its physical condition and perform essential activities such as flying, hunting, and nesting.

A significant deviation from the average weight range could suggest underlying health issues or malnutrition, which can significantly affect the eagle’s ability to survive and thrive in its environment.

Impacts hunting ability and success

The weight of a bald eagle directly influences its hunting ability and success. A well-nourished eagle with an optimal weight can soar through the skies with agility, enabling it to spot prey from great distances.

Additionally, a higher weight provides the necessary power and strength for the eagle to capture and carry its prey back to its nest. On the other hand, an underweight eagle may have reduced stamina and may struggle to catch enough food to sustain itself, leading to a decline in its overall hunting success.

Influences mate selection

Weight also plays a role in the mate selection process for bald eagles. Female eagles, who are typically larger than males, are known to prefer mates that are healthy and well-fed. A larger and heavier male eagle may indicate that it is more successful in hunting and providing for its potential offspring.

This preference for weightier partners ensures the survival and success of future generations, as it increases the chances of the offspring inheriting the same advantageous traits.

To learn more about the weight of adult bald eagles and its significance, you can visit the Audubon Society’s website, which provides comprehensive information on various aspects of bald eagle biology and behavior.


With their six-foot wingspans, bald eagles need substantial weight to stay aloft and hunt effectively. Adult eagles usually weigh 8-14 pounds, with females typically larger than males. Eagle weights can fluctuate based on habitat, age, and time of year.

Carefully tracking bald eagle weights provides key insights into the health and fitness of this iconic raptor.

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