Who builds the nest?
Male and female eagles build the nest together. Both eagles will bring sticks to add to the nest structure and arrange them within the nest. The nest building activity is part of their pair bonding.

How big is an eagle’s nest?
The average bald eagle nest is 4 to 5 feet in diameter and 2 to 4 feet deep. Each year the adult pair will add 1-2 feet of new material to the nest. The largest recorded bald eagle nest, located in St. Petersburg, Florida, was 9.5 feet in diameter, 20 feet deep and weighed almost 3 tons. Golden eagle nests, while large, are generally smaller and flatter than bald eagle nests. Visit the National Eagle Center to see our life-size replica bald eagle nest – climb in and see just how big it is!

When do eagles build the nest?
Nest building may begin 1-3 months prior to mating and is considered part of the breeding process. Breeding season varies regionally, beginning in November and December in southern areas. Eagles in Minnesota typically begin nest building in January and may lay eggs as early as mid-February.

Do eagles use the same nest every year?
Eagles have strong nest site fidelity, meaning they return to the same nest and nesting territory each year. If they successfully produce young at a nest, they are likely to return to that nest year after year. A pair might choose to build a new nest in a different area if their previous nest was unproductive (failed to fledge eaglets) or otherwise proved unsuitable.

Where do bald eagles build their nests?
Bald eagles nest in trees usually choosing the tallest living tree (super canopy) with accessible branches. The nest is built high in the tree below the crown supported by large forked branches near the trunk. In some coastal areas of Alaska and Canada where there are few tall trees, bald eagles will nest on the ground.

Where do golden eagles build their nests?
Golden eagles usually nest on cliffs or in trees in open or semi-open habitat. They avoid heavily forested and developed areas but have been observed nesting on human-made structures such as observation towers or windmills.

How do eagles choose a nest location?
Bald eagles typically choose to nest in a forested area close to water. While eagles typically avoid human activity, in states with large eagle populations bald eagles will nest in developed areas.

Golden eagles prefer open or semi-open undeveloped habitat. When nesting on cliffs, the selection of the site may be based on an exposure that protects the nest and eaglets from inclement weather conditions.

What is the nest made of?
A bald eagle nest is constructed of interwoven sticks. The interior is lined with grass, corn stalks, and other material. The bowl filled with soft materials including moss (which may serve as an insect repellent) and the downy feathers from adults.

Golden eagle nest materials reflect the habitat in which they are built. They are composed primarily of sticks and vegetation, but animal bones, shed antlers and human-made items like wire may be used.

How long does it take to build a nest?
Initial nest building generally may take 1-3 months. Each breeding season, eagles add material to the nest and may increase the size by up to a foot in height and diameter each year. Many bald eagles in the Upper Mississippi River valley engage in some nest building in November when the photo period is similar to that in the spring breeding season when they are actively nest building. Bald eagles in the Mississippi River valley often return to their nest, add material and engage in courtship displays in mid-January.

How long do they use the nest?
Eagles have nest site fidelity and will use a productive nest year after year adding new material to it each year. A pair of eagles may use a nest until the nest itself becomes so large that the tree can no longer support it. In such a case, the pair might build a nest in the same territory, nearby the previous nest.

Do eagles have more than one nest at a time?
Some bald eagles will have a second nest in their territory. They may use one nest for a few years and then move to the second nest for a period of time.

Do bald eagles defend territories around their nests?
Yes. The size of the territory defended depends on location and the abundance of food in that area. In an area with abundant food resources, a territory might be quite small, with other eagles’ nests as close as one mile away. Bald eagles will vigorously defend their territories from intrusion by other eagles, particularly during nesting season.

Do golden eagles defend their breeding territories?
Yes. A golden eagle breeding territory is typically quite large.

When does an eagle begin breeding?
An eagle is sexually mature and ready to breed at about 4 to 5 years of age. For bald eagles, the complete white head and tail are signs of sexual maturity. Golden eagles also attain their adult plumage at 4-5 years of age, when they are sexually mature and typically begin breeding.

When do bald eagles lay their eggs?
Breeding season varies by latitude. In Florida, egg laying may begin in November whereas in Alaska, egg laying typically occurs in late April through May. In Minnesota, the breeding season typically runs from late-February to early March in the southern part of the state through April into early May in the north.

What is the courtship process?
Eagles engage in dramatic courtship displays that involving swooping flight, aerial stick exchanges and cartwheeling. These behaviors are all part of courtship and pair bonding.
Many of these behaviors also test the strength and agility of the potential mate.

Do eagles mate for life?
Generally, yes. Eagles engage in significant courtship and pair bonding behavior. Once a pair has succeeded in breeding, the pair will likely remain together for many years. However, if a mate dies or does not return to the nesting site for the breeding season, studies show that the surviving eagle generally will find a new mate very quickly. The remaining mate will likely use the existing nest with a new mate because of eagles’ strong nest site fidelity.

How do they mate?
While courtship displays take place in flight, eagles do not mate in the air. Rather, copulation occurs on a branch or in the nest with the male mounting the female. During copulation, the cloaca of the male and female touch and sperm is transferred from the male to the female in what is known as the cloacal kiss. Copulation may occur several times a day over a period of days.

How long after mating does the female lay her eggs?
Approximately 5-10 days after a successful copulation.

What color and size are bald eagle eggs?     
Bald eagle eggs are off-white in color and average about 3 inches long by 2 inches wide. The average weight is 4-4.5 oz.

What color and size are golden eagle eggs?    
Golden eagle eggs are off-white with irregular brownish spotting and average 3 inches long by 2 inches wide. The average weight is 5 oz.

How many eggs does a bald eagle lay?
The average clutch (group of eggs) is 1-3. There are reports of 4 eggs in a clutch but such an event is very rare. The eggs are laid one at a time with a separation of a day or two between each egg and hatch in the order they are laid.

How many eggs does a golden eagle lay?
The average clutch is 1-3 eggs with occasional reports of 4. The eggs are laid in 3 to 4 day intervals and hatch in the order they are laid.

How many broods does an eagle have each year?
One brood each year although in southern areas there have been reports of a second brood (a replacement clutch) if the first clutch is lost during incubation.

How long before they hatch?
Incubation for bald eagles is about 35 days. For golden eagles, the incubation period is between 40-45 days. It can take a day for the hatchling to completely break free of the egg after pipping (cracking the egg). Eggs hatch in the order in which they were laid.

How long until the eaglets fledge?
Bald eagles fledge at about 10-14 weeks. Golden eagles fledge in 7-11 weeks. Prior to their first flight, nestlings will flap their wings in the nest or while jumping to an adjacent branch in behavior known as branching.

Who incubates the egg?
After it is laid, the egg must be constantly kept warm, or incubated, and protected from predators. Both males and females share incubation responsibilities but the female typically spends more time on the nest than the male. Males leave the nest to hunt, often providing food for the female. However, the female will sometimes leave the nest to hunt for herself, at which times the male will be called upon to remain at the nest.

How do eagles keep the eggs and young eaglets warm?
The body heat of the parent keeps the developing egg warm. Like most birds, eagles develop a brood patch, or bare spot on their belly, to better facilitate heat transfer to the egg during incubation. Both male and female eagles develop a brood patch.

Are juvenile bald eagles larger than their parents?
No, however they can appear larger in the first year because of longer flight feathers which aid the fledgling as they are learning to fly. After the first molt, the wing feathers will be the same size as an adult’s.

When do eagles fledge?
Bald eagle young are generally ready to fledge, or take their first flight, by 10-12 weeks of age. Young golden eagles typically fledge around 10 weeks of age.

When do bald eagles attain full size?
The juvenile plumage is complete in 10-14 weeks, by which time they are generally fully grown. Some scientists believe a juvenile may continue to grow for a short time after fledging.

When do golden eagles attain full size?
Golden eagles attain full skeletal size in 8-10 weeks although their muscle mass and flight feathers reach full growth post-fledging.

How do you tell the age of an eagle?
In the first five years of life an eagle’s age can be determined by its plumage. Juvenile eagles go through five distinct annual color morphs. Once an eagle achieves maturity, their plumage remains the same throughout their life, and there is no visual clue to determine the eagle’s age.

How do young eagles learn to fly? Is it true eagles carry their young to help them learn to fly?
No. An adult eagle can lift only about 1/3 of its weight. By the time a juvenile is ready to fly, it weighs as much as an adult.
Fledgling eaglets practice attaining life in a process called branching. First flights are generally downward glides from the nest to a lower branch or the ground.

How are the eaglets fed?
Both male and female feed the eaglets by tearing pieces of food and delivering it to the young. Parents do not ensure that all eaglets are fed equally. The largest eaglet gets the majority of the food.

Will the juveniles return to the nest?
Studies show that juveniles are generally nomadic in the first four years of their life and can cover extensive geographic areas. The studies also show that when the juveniles are ready to mate, they tend to return to the general area where they were born. If a juvenile attempted to return to its birth nest, the adult pair would drive them away as they would any intruding eagle.

At what age does is an eagle begin breeding?
An eagle is sexually mature and ready to breed at about 4 to 5 years of age.

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