Black-shouldered Kite - Breeding

Breeding

Aerial courtship displays involve single and mutual high circling flight, and the male may fly around slowly with stiff exaggerated flaps, commonly known as butterfly-flight. Courting males dive at the female, feeding her in mid-flight. The female grabs food from the male's talons with hers while flipping upside-down. They may lock talons and tumble downwards in a ritualised version of grappling, but release just before landing. All courtship displays are accompanied by constant calling.

Black-shouldered Kites form monogamous pairs. The breeding season is usually August to January, but is responsive to mice populations, and some pairs breed twice in a good season. Both sexes are involved in building the nest, which is a large untidy shallow cup of sticks usually in the foliage near the top of trees, taking about two weeks to complete the nest-building. The flat nest is built of thin twigs and is around 28 to 38 cm (11 to 15 in) across when newly built, but growing to around 78 cm (30.7 in) across and 58 cm (22.8 in) deep after repeated use. The nest is lined with green leaves and felted fur, though linings of grass and cow dung have also been reported. It is generally located in the canopy of an isolated or exposed tree in open country, elevated 5 to 20 m (15–60 ft) or more above the ground. Black-shouldered Kites have been known to use old Australian Magpie, crow or raven nests.

Females perform most of the care of eggs and nestlings, though males take a minor share of incubation and brooding. The clutch consists of three to four dull white eggs of a tapered oval shape measuring 42 x 31 mm and with red-brown blotches that are often heavier around the larger end of the egg. The female incubates the eggs for 30 days and when the eggs hatch the chicks are helpless but have soft down covering their body. For the first two weeks or so the female broods the chicks constantly, both day and night. The female does no hunting at all for the first three weeks after hatching, but calls to the male from the nest, and he generally responds by bringing food. The female feeds the chicks with the mice brought back to the nest by the male, feeding them in tiny pieces for the first week or two, at which time the chicks are capable of swallowing a mouse whole. The nestling period lasts around 36 days, and the post-fledging period at least 36 days with parental feeding for at least 22 days. When the chicks are older both parents take it in turns to feed them. Black feathers start to appear along the chicks' wings when they are about a fortnight old, and they are fully fledged and are ready to fly in five weeks. Within a week of leaving the nest the young birds are capable of hunting for mice on their own.

Juveniles disperse widely, taking up territory that can be as far as 1,000 km (600 mi) from the nest site.