Golden Eagle Breeding Habits

In the golden eagle range, some populations are year-round residents, while others migrate between their wintering and breeding grounds. Resident and migratory eagles are rather consistent in their breeding schedules, although they do some things slightly differently. They mate for life and nest in multiple alternate nests within their breeding territory.

  • Golden Eagles mate for life.
  • Multiple nests are built within their territory and used alternately.
  • In North America, the golden eagle breeds between March and August.
  • The female lays 1 to 3 eggs, but two are the norm.
  • The female does most of the incubation.
  • Both parents feed the chicks.
  • The breeding period lasts about 4 months.
  • Golden eagles breed once per year.

When is the golden eagle’s breeding season?

The golden eagle begins to lay eggs in late March and early April. Late starters can lay eggs as late as mid-June.

By mid- August most eaglets have left their nest and can be seen in the company of their parents.

The breeding period of the golden eagle lasts about four months, from the moment the first egg is laid until the day the first chick leaves the nest.

The golden eagles that breed in the northerly regions of the species range are mostly migrants. The individuals that breed toward the center and south of the species distribution are non-migratory.

The pre-and post-nesting breeding behavior varies between migratory and non-migratory eagles.

Non-migratory eagles start courtship, nest building, or refurbishing, months before they begin to lay eggs. The pre-breeding and post-fledging periods are longer in non-migratory golden eagles as these have fewer weather-related constraints.

Migratory golden eagles need to migrate to their breeding territories in the north and must complete all breeding activities within a window of optimal weather conditions.

Across the species range, golden eagles begin laying eggs around the same time. However, in migratory populations, pre-breeding courtship displays, nest building, and post-fledging periods must be fit in about 5 months.

  • Some non-migratory golden eagles lay eggs as early as mid-March.
  • Migratory eagles start slightly later.
  • The breeding period lasts approximately 120 days.
  • The courtship display starts earlier in non-migratory eagles.
  • Migratory golden eagles must begin to breed shortly after they arrive in the breeding grounds in the north.

Golden eagle pair formation 

Golden eagle mated pair. Photo: Thy Bun.

  • Non-migratory golden eagles form pairs throughout the year. Mated pairs remain together.
  • Details of pair formation among migratory eagles are not well understood.
  • Copulation begins earlier in resident populations than in migratory ones.

Non-migratory pairs build new nests or refurbish existing ones, perform courtship flight displays, and interact with each other months before beginning to lay eggs in March and April.

Such interactions suggest that pairs are being formed, and those already formed are reinforcing their pair bond.

Migratory golden eagles spend the non-breeding season away from their breeding territories. When they return to their breeding grounds, they must start laying eggs shortly after arrival.

Migratory birds that have already formed pairs typically return to the same breeding territory. 

New pairs or individuals that lost their mate and need to find a new mate to breed need to do so rather fast. 

Male and female courtship displays are performed by migratory golden eagles upon arrival to the breeding territories. However, the dynamics of pair formation among migratory eagles are not known.

Are golden eagles lifelong partners? 

The golden eagle mates for life as long as both members of the pair live. If one of the birds dies or disappears, the surviving birds will find a mate to breed with.

The surviving bird usually stays in the same territory and breeds with the new mate there.

Mating pairs remain in or near breeding territories year-round.

Migratory pairs usually stay apart during the winter and return to the same territory for breeding the following year.

The golden eagle forms monogamous relationships 

Monogamy is the norm for golden eagles. On very rare occasions, it is possible for two males to breed with a female. 

The three-bird family unit uses one territory. The two males copulate with the female, and all three birds participate in building a nest, incubating the eggs, and raising the young.

This particular mating system has only been reported a few times among golden eagles. In those instances, breeding attempts were successful.

The Nest of the Golden Eagle

Golden eagle on nest. Photo: Buffalo Bill Center of the West.

  • While not clear, the female golden eagle chooses the nest site to breed.
  • Pairs can nest on the same or multiple alternate nests within their territory.
  • They can build a nest in 4 to 5 weeks. 
  • The golden eagle typically nests on tall trees and inaccessible cliffs. 
  • The size of the nest varies from 0.6 to 7-yard deep.

The nest of golden eagles is classified as a platform nest. Typically, a nest is composed of a bottom layer of coarse branches of about 2 to 4 cm in diameter and a meter or longer in length. 

The nesting material becomes thinner and shorter towards the top of the nest. The top layer has a central depression lined with fine nesting material, including grasses, thin twigs, lichens, and moss. 

The central depression is where the female lays the eggs and is called the “bole” of the eagle’s nest.

Some golden eagle nests contain bones, hides, and other parts of their prey. Plastic, cardboard, fabric, and similar materials are often picked up by golden eagles building a nest.

Most golden eagle nests in trees have a round shape. Nests on cliffs can be round if there is enough space or adopt the shape of the available space on the shelf on which the nest is placed.

Golden eagle nest size

Golden eagle nests vary widely in size. A nest can be a shallow platform or one of the biggest bird nests.

The size of a golden eagle can be very large because nests are reused yearly. The pair adds nesting material on top of the existing nest at the beginning and through the breeding season, increasing the nest size and depth.

Some golden eagle nests can be used for decades, although not necessarily by the same pair.  

 Nest DiameterNest Depth
Dimensions of golden eagle nests2.6 – 8.5 feet 2.3 -23 feet

Where do golden eagles build their nests?

Golden eagles are rather flexible when it comes to places to build a nest.

Most nests are built on cliffs, the top of tall trees, and similar elevated structures. 

Unusual places where golden eagles have built a nest include embankments, rocky hillsides, and even on the ground on predator-free lake islands.

Man-made structures that look like tall trees are also used as nest sites. Examples include communication towers, power transmission structures, and nesting platforms. 

The apparent criteria used by the golden eagle to choose a nest site is not quite clear. Local geography, vegetation cover, and the presence of human-made structures play an important role in determining the ideal nest site.

Based on known golden eagle nests sites, breeding pairs seek places that meet common criteria as follows:

  • Proximity to hunting areas
  • Tall enough places that provide a wide view of the surrounding ground.
  • Sites with the persistent updraft of air for effortless access.
  • Sites with unobstructed access for easy landing and take-off. 
  • Sites inaccessible to land predators.

The process of nest selection by mated golden eagles 

It is not entirely clear, but golden eagle biologists suggest that the females select or heavily influence the selection of nest sites.

Regardless of whether the female, the male, or both eagles chose the nest site, they nest on what is available to them.

Where tall trees are readily available golden eagles use them for nesting. Golden eagles nest almost exclusively on cliff shelves in treeless areas with plenty of cliffs.

Where no cliff or tall structures are available eagles build nests on or near the ground.

Both male and female golden eagles participate equally in the construction of new nests or refurbishing existing ones.

The building of the nest

Both the male and female search for already broken sticks on the ground. They also walk up to a suitable branch, break it off with their beaks and legs, and then carry it to the nest. 

To build their nests, eagles use both live and dead branches.

Golden eagles spend varying amounts of time building or refurbishing nests, depending on whether they are migratory or resident.

Non-migratory eagles spend their non-breeding period in or around their breeding territories. Birds have been observed to build new nests and refurbish existing ones at any time of the year at a rather slow pace.

Golden eagles prepare their nests one month in advance of egg-laying.

The time it takes a golden eagle pair to build a new nest can range from 4 to 6 weeks based on field observations.

In migratory golden eagles, nest building is more hectic. After arriving in the nesting territories, eagles begin to lay eggs only weeks later. As a result, nests must be built or refurbished quickly to accommodate the eggs.  

During incubation or raising their young, migratory golden eagles often build alternate nests, which may respond to having several options ready to use upon arrival at the breeding grounds the next breeding season.

Both eagles continue adding freshly cut branches with leaves to the nest. As the chicks grow in the nest, this behavior intensifies. 

According to golden eagle biologists, adding green leaves to the nest can indicate nest occupancy to other eagles. Adding branches with green leaves of certain plants may also serve as a parasite repellent.

Does the golden eagle use the same nest every year?

Golden eagles can use the same nest in consecutive years or nest in one of the several alternate nests they build within their territories.

Alternate nests are an important aspect of the golden eagle’s reproductive biology. Field studies found that most golden eagle territories have more than three alternate nests.

One territory had 18 alternate nests.

Alternate nests can be located on the same cliff shelf adjacent to each other or 4 miles apart. The number of nests and the distance between them appear to depend on the territory’s geography.

A study of many active golden eagle territories found that pairs never used the same nest for more than 5 years in a row. Nests were only used for 2 to 4 consecutive years before switching to another nest.

Many alternate nests are never used for breeding.

What are the Eagle’s nest predators?

Golden eagles have few land nest predators because their nests are generally inaccessible. 

Aerial predators such as gyrfalcons (Falco rusticolus), Great Horned Owl (Bubo virginianus), and Common Raven (Corvus corax) can take small eaglets from unattended nests. 

Breeding eagles fiercely attack any potential nest predators, even when they are far from the nest.

Eagle nests placed in tall trees can potentially be raided by climbing mammals such as raccoons.

Egg-laying and Incubation

  • Most nests contain 2 eggs
  • The female begins incubation after laying the first egg.
  • The female does most of the egg incubation.
  • The eggs are pale with scattered brown spots and blotches.
  • Golden eagle eggs are approximately 3 inches long, 2.3 inches, and weigh 0.3 lb.
  • A golden eagle’s incubation period is 42 days.

How many eggs does a female golden eagle lay? 

A female golden eagle typically lays between 1 to 3 eggs per clutch, with the majority of nests containing 2 eggs.

After the first egg is laid, the female lays another egg every other day to complete the clutch.   

Four-egg clutches are rare. A golden eagle nest with 5 eggs was reported in California (DeGroot 1928). 

A comprehensive review of 322 golden eagle nests in western North America found that:

  • 76% of the nests contained 2 eggs
  • 14% contained 1 egg and 
  • 10% contained 3 eggs 

Golden eagle eggs are whitish to creamy white, marked with dots and blotches of various sizes. The markings can vary in size and density, and color tone.

Eggs markings are denser on the wide side of the egg.

Female golden eagles can delay or suppress laying eggs

The onset of the egg-laying period can depend on weather conditions as this relates to vegetation and prey abundance

If the weather conditions are conducive to abundant prey, female eagles will lay early and have larger clutches.

Alternatively, females may delay reproducing if the weather is unfavorable to an abundance of prey. If the weather is poor, females skip laying eggs and don’t try to breed until the following year.

Incubation of the eggs 

The female golden eagle does most of the incubation during the day and night while the male brings food and protects the nest.

The female takes breaks of about 50 minutes to an hour while the male takes over incubation. These breaks generally occur when the male brings food to the nest, and the female takes time off the nest to eat.

The female starts incubating the first egg and continues incubating as she lays the rest of the clutch. 

The incubation period of golden eagles is 42 days (ranging between 41 to 45 days).

Egg-hatching and care of young

  • The eggs do not all hatch at the same time.
  • The chicks hatch with a thin layer of grayish down.
  • The mother broods the young for the first 30 days after hatching.
  • The chicks leave the nest after 60-70 days after hatching.

Eggs hatch asynchronously, i.e. not all hatch at the same time. The first egg hatches first as it has been incubated for more days since the day it was laid.

All eggs generally hatch in a period of 4 days or less.

Eaglets first burst a whole and can take up to 2 days to be completely out of the eggshell.

The chicks hatch with a fine layer of grayish-white down, which covers the entire body. Their eyes are partially open.

Although the chicks are wet when they hatch, the down dries within 2 hours of hatching. 

Chicks at hatch have pale pinkish-pink legs and toes, white to pinkish claws, and a black beak. 

Caring for chicks in the nest

Golden eagle chicks are altricial. They depend entirely on their parents. 

The female broods the hatchlings while the male brings food. For approximately the first 20 days, only the female feeds the young directly with the food the male brings.

In the first 20 days, the chicks cannot thermoregulate their temperature and depend on the parents to do so. The female continues brooding and shading the chicks until day 30. She broods the chicks through the night.

The length of time a female broods the baby golden eagles varies with regional weather conditions. In regions with cold nights, the female broods the young until day 45 after hatching.

By days 34  to 37, the chicks are able to eat by themselves the carcasses or pieces of meat the parents drop on the nest. 

By day 55 chicks can tear and open up carcasses of small mammals brought to the nest by the parents.

Young golden eagles fledge the nest 9 to 10 weeks after hatching.

Loss of nestlings

Loss of the young eaglets to predation is unlikely as adult golden eagles build nests inaccessible places.

The main reason eaglets are lost is due to conflicts among themselves.

There are always fights between siblings in golden eagle nests. Despite sibling rivalry, all chicks fledge successfully if food is available for everyone.

When food is scarce, sibling conflicts recur. The older and larger eaglets monopolize the food brought to the nest.

In situations of severe food scarcity, the smaller siblings are generally killed or pushed out of the nest by the larger and dominant eaglets.