Tag Archives: Bald Eagle Chicks

When Do Eaglets Leave The Nest?

April 29, 2018Bald Eagle, Kodiak WildlifeBald Eagle Chicks, Eagle growth in Alaska, Eagles on Kodiak Island, Eaglets, Growth of eaglets, Robin Barefield, When Eaglets leave the nestadmin

Three weeks after hatching, eagle chicks, or eaglets, molt to a thicker, darker down which remains until the first set of feathers develop. At this stage, one of the parents remains near the nest to shelter the chicks from direct sunlight, inclement weather, and anything else that can harm them.

When an eaglet first hatches, its bill and eyes are dark-colored. Over the course of three to four years, the bill lightens to a swirl of shades of brown, then to yellow-brown, and finally to bright yellow. The eyes lighten to buff yellow by one-and-one-half-years, light cream by age two-and-one-half, and pale yellow by three-and-one-half.

As the chicks develop feathers and grow, the parents spend less time at the nest and more time hunting for food. The eaglets grow very rapidly as long as the parents can provide sufficient food. If the parents are unable to find enough food, the smallest chicks might die.

At one-and-one-half to two-weeks, most young eagles weigh one to two lbs. (500 to 900 grams). Between 18 – 24 days, chicks gain four ounces (100-130 grams) per day, a faster weight gain than at any other stage of their development. Eaglets begin feeding themselves around the sixth to seventh week, and by eight weeks, they can stand and walk around the nest. At sixty days, eaglets are well-feathered and have gained 90% of their adult weight. Large nestlings consume nearly as much food as adults.

Chicks remain in the nest for ten to twelve weeks. A week or two before they fledge, they can be seen on the rim of the nest exercising their wings and holding onto the nest with their talons. They flap their wings and may even lift off the nest. A chick can fall or be blown off a nest while exercising, and if it can’t make it to another branch, it might fall to its death. Biologists estimate one in seven eaglets fledges prematurely, either falling or jumping from the nest before it can fly.

Once their muscles and wings are strong enough, eaglets are ready to leave the nest. What prompts the chicks to fledge is a matter of speculation, but at some point, the parents cut back on the amount of food they provide their young, and they may even use food to lure the chicks away from the nest. Males fledge at an average of 78 days, and females fledge at an average of 82 days. Research in Southeast Alaska shows fledging there occurs on average in mid-August.

The first several flights of a fledgling are very clumsy, and their first few landings are usually crash landings. Juvenile birds have longer wings and tails than adults, and this makes learning to fly easier for them. As an eagle matures, its wings become shorter and narrower, and the tail gets shorter with each molt.

Immature eagles usually stay within a half-mile radius of the nest for the first six weeks after fledging, and they may even continue to receive food from their parents during this time. Eight to ten weeks after fledging, they seem to develop a stronger instinct to move further away from the nest.

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Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.

Mystery Newsletter

When do Bald Eagles in Alaska Lay Their Eggs, and When do the Eggs Hatch?

April 22, 2018Bald Eagle, Kodiak WildlifeBald Eagle, Bald Eagle Chicks, Bald Eagle Eggs, Bald Eagle Eggs Hatching, Bald Eagles in Alaska, Bald Eagles on Kodiak Island, Robin Barefieldadmin

Bald eagles lay their eggs in mid to late May in southern areas of Alaska, although one study in Southeastern Alaska indicated that they might lay their eggs as late as early June. The female lays between one and three off-white-colored eggs in a span of one to three days. The eggs range in size from 2.76 inches by 2.09 inches (70mm by 53 mm) to 3.31 inches by 2.36 inches (84 mm by 60mm).

The eagle pair begins incubating the eggs as soon as they are laid. The male and female share the incubation duties, and each mate hunts for its own food. Studies show that for 98% of the day, either the male or female sits on the eggs. The incubating bird stands up about once per hour and may change positions. A study at several nesting sites on Admiralty Island in Southeast Alaska found eggs were incubated for 95% of the daylight hours with females sitting on the eggs 53% of the time, and males tending the eggs 42% of the time. Brooding time dropped to 79% of the day for the first 10 days after the eggs hatched and by 41 to 50 days after hatching, the brooding time decreased to only 6% of each day. Brooding time increased when it was rainy and decreased when it was sunny. The incubation period takes 34 to 36 days. Since individual eggs may be laid a few days apart, they will not all hatch at the same time.

The hatching process is slow and arduous. It takes chicks twelve to forty-eight hours to fully emerge from the egg. The chick makes the first crack in the shell with its egg tooth, a small, hard bump on the top of the bill. After resting awhile, it then chisels around the large end of the egg. It eventually pushes off the end of the egg and wriggles out of the shell. The egg tooth dries up and falls off four to six weeks after hatching.

During hatching, a chick must undergo several physiological adaptations. Before it hatches, a chick absorbs oxygen through the mat of membranes under the shell. During the hatching process, it must cut the blood supply to these membranes and trap the blood within its body. At the same time, it must also inflate its lungs and begin breathing air once it has cracked the shell. The chick must also absorb the yolk sack into its body and seal off the umbilicus.

Newborn chicks are wet, exhausted, nearly blind, and extremely needy. Since a newly-hatched chick can’t regulate its body temperature, the parents must keep it warm. The chick is covered with pale gray down. The skin and scales of the legs are bright pink, the bill is a grey-black with a white tip, and the talons are flesh-colored. After the first week, the legs begin to turn yellow.

Eagles lay one to three eggs, but usually, only one or two chicks survive. Survivability is directly correlated to age. The first chick to hatch will be one to two days older than its siblings, so it will be larger and stronger and able to out-compete its nestlings if food is limited. If a brood has three chicks, the smallest chick usually dies within a week of hatching. Death is not normally caused by injuries from fighting with its siblings, but the chick simply starves to death because the older nestlings get all the food. The older chicks peck the young chick into submission to prevent it from eating enough to survive. By doing this, the older chicks ensure they have plenty of food.

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Mystery Newsletter

Bald Eagle Courtship, Mating, and Chicks

April 19, 2015Bald Eagle, Kodiak WildlifeBald Eagle Chicks, Bald Eagle Courtship, Bald Eagle Mating, Kodiak Island Eaglesadmin

The piercing, high-pitched call causes me look up at the sky, where I see two bald eagles flying in circles several hundred feet above my head. One eagle dives at the other. They touch talons and then separate and soar higher. A few minutes later, one eagle again dives at the other, and this time their talons lock, causing the birds to spiral downward in a motion much like a cart-wheel. I hold my breath as they plummet toward earth, but they finally pull away from each other and fly in opposite directions.

I assume I’ve just observed a courting display, and maybe I have, but biologists have a tough time differentiating between the aerial acrobatics of courting and those of aggression, and it is believed that the two behavioral displays may be closely related. Eagles also display other much-less aggressive forms of courtship, such as perching beside each other on a branch and stroking and pecking at each other’s bills. They also use their bills to stroke the heads, necks, and breasts of their mates.

Bald eagles sometimes mate for life, but if one member of the pair dies, the surviving member will often find a new mate within a year, and if a pair does not produce offspring after several seasons, they may change mates.

Copulation usually takes place near the nest site, and females lay between one and three eggs in mid-May on Kodiak. The male and female take turns incubating the eggs, and each mate hunts for its own food. The incubation period lasts 34 to 36 days, and it takes 12 to 48 hours for a chick to fully emerge from the egg.

During hatching, a chick must undergo several physiological adaptations. Before it hatches, the chick absorbs oxygen through the shell by way of the mat of membranes under the shell. During the hatching process, the chick must cut the blood supply to these membrane and trap the blood within its body. At the same time, it must also inflate its lungs and begin breathing air once it has cracked the shell. The chick must also absorb the yolk sack into its body and seal off the umbilicus.

A newborn chick is helpless and dependent on its parents. It cannot regulate its body temperature, so the parents must keep it warm. Chicks grow rapidly as long as the parents can supply adequate food, and as the chicks develop and grow, the parents spend less time at the nest and more time hunting for food.

By the age of two weeks, most young eagles weigh one to two pounds (500 to 900 grams). Between 18 to 24 days, chicks gain four ounces (100 to 130 grams) per day, the fastest weight gain of any stage of their development. They begin feeding themselves by the sixth or seventh week and can stand and walk around the nest when they are eight weeks old. At sixty days, eaglets are well-feathered and weigh 90% of their adult weight.

Chicks remain in the nest for ten to twelve weeks, and we often see fledglings making their first flights in late August. Most nests where we live are located near the tops of tall cottonwood trees, and I wonder what it must be like for a young eagle to take that first step out of the nest. Their first flights are often very clumsy and quite humorous to watch as they learn how to use their huge wings to fly and master landing on a branch. Juveniles have longer wings and tails than adults, which makes it easier for them to learn how to fly, but it takes a while before they hone their skills, and they make several crash landings before they figure it out. They often continue to receive food from their parents while they learn to fly and hunt.