The breeding cycle (nest-building to fledgling) lasts five to six months.
Includes: high flights above nest area - repeated diving and sweeping upward while emitting croaking calls.
Usually during summer rains. Can occur whenever prey is abundant.
Nesting
Select trees with substantial, flat canopies.
Roosting and nesting occurs in trees, but occasionally on the ground.
Some nests used repeatedly, but more often new sites selected for each round of breeding.
Nest consists of sticks and weeds, thickly lined with dry grass. 3 - 6 ft in diameter.
Nesting period is usually about 80 to 90 days.
Incubation and Hatching
Eggs
Clutch size: 1 - 3 eggs, white and unmarked,
Egg shell green inside, like that of eagles and hawks.
Brooding / Incubation: approximately 42 - 45 days.
Pairs alternate incubating and brooding duties, though the female usually does so overnight. During this time the sitting parent is completely exposed to elements, enduring heat, rain, hail and cold.
Parents may switch shifts incubating or brooding up to six times a day. Display greeting with each shift change.
Life Stages
Nestlings
Lasts 65 - 106 days.
10 - 14 weeks.
No documented aggression between siblings.
Liquid is regurgitated to chicks from the day after hatching until approximately 63 days old.
After the chicks feather, both the male and female parents collect food. Prey swallowed whole are regurgitated by nesting parents onto nest floor. After several weeks they can gulp down whole food.
Nestlings remain within a few hundred meters of the nest during the first month or so, after gliding out of the nest to practice mock kills by stamping on grass tussocks or sticks.
Parents may also dribble water into chicks' mouths.
Young
Fledging: Chicks usually fully developed, with duller plumage and yellow (rather than red or orange) facial skin.
Fledglings return to roost on the nest for at least six weeks after their first flight.
Young remain with their parents for a few months, sleeping together on the same treetop at night.
The parent-child bond gradually diminishes and the family disperses.
Adults
The age of maturity is not known, but expected to be 3 or 4 years.
