How Long Does It Take a Baby Eagle to Grow Up

This article covers the growth and development of baby bald eagles from the time they hatch until fledging.

The article also uses baby bald eagles photos to illustrate their appearance at various growth and development stages. The sequential photo series can help determine the approximate age and stage of growth of bald eagle eaglets in a nest.

1. When do baby bald eagles hatch?
2. Parental care
3. Do baby bald eagles kill their siblings?
4. Growth and development of bald eagle nestlings.
5. How long do bald eagle eaglets stay in the nest?
6. Do adults and young bald eagle clean up the nest?
7. Calls of baby bald eagles.
8. How long do young bald eagles stay with their parents after fledging?

When do baby bald eagles hatch?

After 35 days, a relatively long incubation period, the first egg hatches. The rest of the eggs hatch within approximately the same time the female bald eagle lay the second and third eggs.

The difference in the time of egg hatching is that the female eagle begins incubating the first egg as soon as she lays it, hence initiating embryo formation earlier than in the second and third eggs.

Females bald eagles sometimes lay eggs on successive days, but this is not always the case. Overall, most clutches are completed in 3 to 6 days; consequently, all eggs hatch within the same time period of 3 to 6 days.

The hatching baby eagles crack and pip the eggshell open independently, without any help from the parents.

The timing of egg-hatching varies with latitude from the south to the north. Bald Eagles eggs in the south hatch earlier than eagles in the northern States and Canada.

Region	Approximate date of Egg Hatching
Florida	Egg hatching may start as early as November and as late as May. Most egg hatching starts in January through February.
Chesapeake Bay, Maryland.	Egg hatching starts in January. Most eggs have already hatched by the last week of February through the end of March.
Province of Saskatchewan, Canada.	It appears most of the egg hatching occurs in the second half of May.
Yellowstone ecosystem, Wyoming.	Eagles eggs hatch from early April through mid-May. Egg in nests at higher elevations starts to hatch later than April.
Arizona.	Eggs start to hatch in February through late mid-March.
Country of Mexico.	Eagles eggs appear to start hatching from late January through early February.
Alaska and Yukon Territory.	The egg hatching period extends from late May through the end of June, peaking in the second week of June.

Parental care

After hatching, both the female and bald eagle brood the baby eagles most of the time during the first week. The female does most of the brooding.

After the first week, the parents let the nestling eagles exposed for some time but resume brooding most of the time during inclement weather.

It is estimated that during the first three weeks of the hatchlings' life, the female spends about 90% of the time on the nest taking care of the eaglets while the male brings food for the mother and babies.

During the first three weeks, the female may briefly leave the nest, but the male replaces her, never leaving the eaglets unattended.

After the third week, the parents begin to relax the brood's care, leaving the eaglets in the nest unattended for short periods of time. By the 5th and 6th weeks, the parents take longer periods of time away from the nest and begin to roost away from the nest.

On hot and sunny days, the female may cover the baby eagles from the sun. On cold days she may keep the eaglets warm by attempting brooding the now larger nestlings.

Feeding of the bald eagle eaglets

The first eaglet is fed the first day after hatching and quickly develops a size advantage over the second and third eaglet. During the first 2 and a half weeks, the male brings food for both the female and the chicks.

During the first days after hatching, the female tears tiny pieces of what the male brings to feed the young eagles. As the eaglets grow, both parents tear bigger pieces of food.

By the 4th week, both parents begin to forage for food and bring about the same amount of food to the nest. As the chicks grow older, the female appears to bring more food to the nest than the male.

At about the 7th week the chicks begin to tear pieces of the fish the parents bring to the nest.

The first hatchling gets most of the food most of the time

Field observations of adult bald eagles feeding three 4 week-old eaglets recorded dismal differences in the amount of food each eaglet gets. An adult eagle brought a large fish to the nest and fed the largest eaglet 67% of the fish while the second eaglet received 18.9 % and the third eaglet 13.7%.

In another nest, with three baby eagles, the differences were even more dramatic. The largest eaglet received 96% of the fish, while the second-largest eaglet received 2.5%, and the third chick only received 1.2% of the fish. In this last nest, the smallest eaglet eventually died from starvation.

These two bald eagle chicks stopped fighting after a week and grew without fighting until they fledged.

Do baby bald eagles kill their siblings?

Yes, baby bald eagles can kill each other. Newly hatched nestlings can be very aggressive to each other. They appear to be aggressive by nature. They may engage in fierce fights and hurt each other or terminate the fight and grow together (See video).

Food availability appears to be the driving force in determining how aggressive eaglets are to each other.

When the parents bring plenty of food, broods of 2 or three eaglets do not show much aggression toward each other. When food is abundant, all three eaglets fledge the nest at similar sizes even after showing differences in size at earlier stages in the nest.

However, when food is scarce, the difference in size between the first, second, and third baby eagle becomes more pronounced. The little food brought to the nest is capitalized by the larger eaglet that continues to grow while the others lag. The smallest eaglet is either killed by its larger siblings or dies of starvation.

If there is enough food for two, then both eaglets will grow without any problems. If food continues to be scarce, the larger eaglet gets most of the food brought to the nest and becomes aggressive towards its smaller sibling to the point that it may end up killing it or also drives it to die from starvation.

Besides bringing food to the nest, the adult eagles do not intervene in the eaglet's disputes.

If one of the three eaglets in the nest ends up dying, why do bald eagles lay three eggs?

The bald eagle parents will always try to maximize the number of eaglets on each breeding season. With that purpose in mind, they lay up to three eggs to explore the possibility of being in a season of plenty of food. But if there is not enough food available, they settle for raising only one or two eaglets.

Some ornithologists think that eagles lay three eggs just if one or two of the eggs are not fertile.

Growth and development of bald eagle nestlings.

The following list uses baby bald eagle photos to illustrate the eaglets' stages of growth and development. These photos and associated information can be used as a reference to make an approximate age determinaton of the young bald eagles in the nest.

1-2 Days

Newly hatched baby eagles have a white to light gray coat of natal down. This natal down does not have good insulating properties. The female broods the eaglets keeping them warm the first 9-10 days after hatching.

9 Days

The natal down is replaced by thermal down, which is gray in color and has better insulating properties. By the 15th day of life the eaglets on the nest can thermoregulate on their own.

3 Weeks

Eaglet in thermal down. The entire body is gray in color. Juvenile feathers begin to emerge but are not readily visible.

4 Weeks

Juvenile feathers begin to emerge through the thermal down. The top of the head, back, and lateral tracks are the first to show juvenile feathers.

5 Weeks

Juvenile feathers begin to appear on the breast and belly. Feathers on the head and back continue to grow longer and denser.

5.5 Weeks

Feathers continue to grow. The eaglet has most of its body covered in juvenile feathers. The tail and wing feathers are rather short.

6–7 Weeks

The eaglet's body is covered in juvenile feathers but the sides of the body, thighs, and wing underside still have thermal down. Juvenile feathers are just beginning to emerge on these tracks.

8-10 Weeks

The entire body is covered in juvenile feathers. However, the tail and wing feathers continue to grow for weeks after the eaglets leave the nest.

How long do bald eagle eaglets stay in the nest?

Across the Bald Eagle's range in North America, baby eagle fledge between 8 to 14 weeks after hatching.

Studies of nesting bald eagles in different regions indicate that young eagles leave the nest as follows:

• In California, bald eagle nestlings left the nest on average at 12 weeks
• In Florida, at about 11 weeks (108)
• In Maine, at about 11–13 weeks

The difference in the number of weeks has to do with the timing of hatching, availability of food, and sex of the eaglets.

In general, the first egg to hatch grows bigger and develops faster than the rest. Hence this eaglet leaves the nest sooner.

When the food is abundant during the nesting seasons, baby eagles develop faster and leave the nest sooner than in seasons when food is scarce, and they take longer to develop.

Field observations also indicate that males tend to fledge earlier than females. In nests where the first egg hatched was a female, male siblings fledged earlier than the more developed female.

Do adults and young bald eagle clean up the nest?

The very young bald eagle eaglets tend to defecate outside of the "bole" but still on the nest. As the eaglets grow, they can defecate outside the nest by pointing their rear ends outside the nest before "shooting" their droppings.

Bald eagle nests with eaglets often show a distinctive halo of whitewash on the ground vegetation below the nest.

The adult eagles do not clean out the bones and the rest of the carcasses they bring to the baby eagles. The bones and rest of uneaten carcasses are buried by grass, moss, and other nesting material in the nest. At the end of the breeding season, the nest has a pungent odor.

Calls of baby bald eagles.

Nestling bald eagles begin making faint calls after the first week. However, when they begin to stand up by the 4-5 week, their calls become louder and better composed. Eaglets vocalize softly while in the nest but become much louder when the parents bring food to the nest.

The following are calls o a single bald eagle nestling.

This recording includes the mostly young bald eagles, but adult eagles can also be heard vocalizing.

Young eagles sometimes fall to the ground; do they do it on purpose?

Many young bald eagles indeed fall to the ground, but they do not do it on purpose.

Upon reaching 8 weeks of age or more, the nestlings start flapping their wings to develop muscle strength. First, they flap their wings in place and perform jumps on the nest. Then they start exercising their take-off and landing skills from branch to branch. This is the period where most eaglets miss a landing and fall to the ground.

The eagle parents do not teach the eagle babies how to fly. When the time to fledge approaches, the parents may encourage them to fledge the nest by flying around the nest while vocalizing.

Field observations indicate that up to half of bald eagle fledglings end up on the ground.

Eaglets remain on the ground for several weeks, where the parents continue feeding them until they gain more strength and coordination skills and can fly.

When eagles stay on the ground, they are vulnerable to foxes, coyotes, and mountain lions.

How long do young bald eagles stay with their parents after fledging?

Fledging eaglets need help from their parents for 5 to 10 weeks after leaving the nest. The young eagles depend entirely on their parents for food. In fact, field observations indicate that during the first 5 weeks after fledging, the eaglets cannot catch their own food.

Juvenile eagles follow the parents everywhere, including the trips to the feeding grounds where they observe the adults catching food. The eaglets start progressively developing their own hunting skills and ability to find food. Eaglets start first by getting floating dead fish or scavenge on carcasses.

The majority of their diet during the time they travel with their parents is composed of fish.

Young bald eagles appear to learn to hunt mostly on their own by trial and error. This is because they begin to hunt for waterfowl and other animals long after becoming independent and are no longer with their parents.

References:

Bortolotti, G. R. (1984c). Evolution of growth rate and nestling sex ratio in Bald Eagles (Haliaeetus leucocephalus). Ph.D. thesis, Univ. of Toronto, ON.

Bortolotti, G. R. (1986a). Evolution of growth rates in eagles: sibling competition vs. energy considerations. Ecology 67:182-194.

Buehler, D. A. (2020). Bald Eagle (Haliaeetus leucocephalus), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.

Fraser, J. D. (1981). Breeding biology and status of Bald Eagles on Chippewa National Forest. Phd Thesis, Univ. of Minnesota, Minneapolis.

Hunt, W. G., R. E. Jackman, J. M. Jenkins, C. G. Thelander and R. N. Lehman. (1992c). Northward post-fledgling migration of California Bald Eagles. Journal of Raptor Research 26:19-23.

McClelland, B. R., P. T. McClelland, R. E. Yates, E. L. Caton and M. E. McFadden. (1996). Fledging and migration of juvenile Bald Eagles from Glacier National Park, Montana. Journal of Raptor Research 30:79-89.

Wood, P. B. (1992d). Habitat use, movements, migration patterns, and survival of subadult Bald Eagles in north Florida. Ph.D. Thesis, Univ. of Florida, Gainesville.

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How Long Does It Take a Baby Eagle to Grow Up

Source: https://avianreport.com/baby-bald-eagles/

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