Generally seen singly or in pairs (3) (9), the black-shouldered kite is occasionally gregarious (2) (3), forming small family groups and roosting communally (3). This small bird of prey is active by day and at dusk (2) (3), being seen most frequently in the early morning or in the evening (9).
The black-shouldered kite can often be observed sitting on poles, wires or the topmost branches of dead trees (2) (5) (9). After landing on its perch, this species is known to flick its tail up and down (2) (3), possibly as a territorial demonstration (3). In flight, the black-shouldered kite glides on raised wings (2), hovering in search of prey with rapid, shallow beats and lowered legs (2) (3). It also sometimes hunts from a perch (2).
The black-shouldered kite feeds mainly on small mammals, particularly house mice (2) (3) (9), and large insects such as grasshoppers (2) (3) (5) (6) (9). This species also takes small birds (2) (3) and reptiles (2) (3) (5) (6) (9). After dropping onto its victim on the ground feet first (2) (3) (9) or hawking after insects in the air (5), the black-shouldered kite eats its prey in flight or carries it to a perch (3).
Populations of the black-shouldered kite generally breed between June and October in the east of the species’ range, and populations in the west breed from November to January. When food availability is high, the black-shouldered kite may breed at any time of year and sometimes produces two broods in the same season (3).
Aerial displays are performed during the breeding season, and the black-shouldered kite tends to produce a lot of weak calls during this time. In one particularly dramatic type of display, one of the birds will dive towards its mate, which rolls over and presents its claws, and the pair may then grapple and cartwheel in mid-air (3).
The black-shouldered kite’s nest is usually built in the fork of a large tree, between 4 and 35 metres above the ground. The nest itself is a flat platform of thin twigs lined with green leaves, and measures 27 to 45 centimetres across, and between 10 and 15 centimetres deep. A clutch of two to five eggs is laid, although three or four is most common. Black-shouldered kite eggs are incubated for 29 to 34 days, and the chicks fledge the nest 33 to 38 days later, although they remain dependent upon the adults for up to a month more (3).