Class: Aves (Birds)
Body length: 31 to 39 inches (80 to 99 centimeters)
Weight: male, 6 to 9 pounds (2.7 to 4.1 kilograms); female, 7 to 9 pounds (3.2 to 3.9 kilograms)
Incubation: 49 to 51 days
Number of eggs laid: 1 or 2
Age of maturity: about 4 years
Conservation status: lower risk
• The world’s first zoo-born crowned eagle hatched at the San Diego Zoo in April 1996.
• A crowned eagle can swoop after prey in the air at 100 miles per hour (160 kilometers per hour) yet brake to a halt within 20 feet (6 meters). It pushes its powerful wings against the air currents to slow down.
• The crown feathers of the crowned eagle are valued among African tribesmen as ornaments.
• The flight of the crowned eagle is remarkably quiet, much like the silent flight of owls.
• The crowned eagle is the only surviving member of its genus. The Madagascar crowned hawk-eagle Stephanoaetus mahery died out about 1,000 years ago after humans arrived in Madagascar and hunted its main prey, giant lemurs, into extinction.
Birds: Crowned Eagle
The most powerful eagle in Africa
Crowned eagles are not the largest eagles in Africa—martial eagles claim that title—but they are the most powerful. Their legs are thick, and they have a very long talon on the back toe that helps them kill animals several times their size. This eagle species lives in the woodland forests and rain forests of Africa. They are often seen on Africa's savannas as well. Built for moving among trees, the crowned eagle's wings are short and broad and its long tail helps guide the bird like a rudder guides a boat. These features allow the eagle to fly easily through the branches.
Crowned eagles are also known for their cry. They call out often in a very loud voice. The male’s call, “kewee-kewee-kewee,” is higher pitched than the female’s call. The adults and chicks both call to each other at the nest, especially when the parents bring food for their young.
A spectacular courtship
Like many eagles, crowned eagles perform a beautiful courtship flight to impress a female. The male flies very high into the air and makes a series of swooping dives and climbs, like a roller coaster. At the top of each loop, he flaps his wings quickly several times, throws his head back, and calls loudly for up to 30 seconds. If the female joins him, they may lock talons and cartwheel down toward the ground, only letting go at the last second. At the nest, the male displays for the female by running around her with his wings raised. Breeding usually occurs between July and October, after the rains have stopped.
The pair uses the same nest for many years until a new pair inherits it. The nest is made of sticks and lined with fresh green branches. The birds add new material to the nest each year, and over time the nest can grow up to 8 feet (2.4 meters) across and 10 feet (3 meters) deep. It typically rests in a 40- to 150-foot-tall (12- to 46-meter-tall) tree.
Only one can survive
The female crowned eagle lays one or two eggs, which are white and speckled with reddish brown. She incubates the eggs for most of the next 49 days, while her mate brings her food every three to five days. Sometimes the pair will swap roles. The chick hatches, covered in down, and develops its first feathers at about 40 days. If there are two chicks, the stronger (usually the firstborn) kills the weaker one soon after hatching. The father brings fresh branches and food to the nest for the first two months, and both parents are very good at protecting their baby. If anything approaches the nest, the parent attacks it fiercely.
The chick's crest feathers (or "crown") appear at about two months of age, and it has all of its feathers 76 days after hatching. The young crowned eagle starts wing-flapping exercises to strengthen its flight muscles at 40 to 50 days old and is ready to take its first flight by the time it is 4 months old. The youngest crowned eagle seen to make a kill on its own did so 61 days after fledging, but more often its parents feed the juvenile every 3 to 5 days for the next 9 to 12 months while the youngster practices its hunting skills. Because the offspring is so dependent on its parents for so long, the mated pair must wait another year before breeding again. This means the pair usually raises only one chick every two years.
Are you my mother?
A juvenile crowned eagle looks very different from an adult. It has light gray-brown feathers on its back and its wings are edged in white, making the bird look like it has scales. Its head, breast, and belly are white, and its wing and tail feathers have gray bars. By the time it is three years old, the young crowned eagle has changed into its striking adult coloration: a dark brown head with long crest feathers tipped in white. Adult crowned eagles also have a breast that is cream or reddish with black bars and wings that are black on the top and reddish underneath. Like many raptors, the female crowned eagle often has more bars on her breast to provide better camouflage while she is sitting on the nest. She is also larger than the male.
Hunting big game
As the most powerful eagle in Africa, the crowned eagle is able to kill animals weighing up to 44 pounds (20 kilograms). The eagle's long hind talon helps break the prey’s spine or suffocate it. A favorite method of hunting is to sit in a tree overlooking a waterhole or clearing, then simply drop down onto the prey. When hunting monkeys, a crowned eagle flies over the rain forest canopy until a troop of monkeys can be heard. The eagle lands on a branch and tries to get as close as possible to the monkeys without being seen before attacking. A crowned eagle pair may hunt together: the male flies high and calls out to get the attention of monkeys in the trees below; the female then skims the treetops and grabs a confused monkey. They prefer to carry their kill into a tree to eat in safety, but they can't carry anything heavier than themselves. If the kill is too heavy, it will be torn apart on the ground and the pieces stored and eaten over several days or brought back in pieces to the nest. Crowned eagles also eat small antelope, mongooses, feral cats, rats, monitor lizards, and snakes.
Crowned eagles and people
Crowned eagles are fairly common throughout their range, since they prefer thick forests where people don't usually live. If they venture out in open lands where livestock is normally found, they are sometimes shot by ranchers who fear the eagles might prey on their livestock. But since crowned eagles prefer forest habitat, their greatest threat comes from people destroying those forests.