Like other kestrels, the nankeen kestrel characteristically hovers while hunting, keeping the body horizontal and the head still as it scans for prey. When prey is spotted, the kestrel drops towards the ground until it is near enough to strike (2) (3) (5) (6). The diet of the nankeen kestrel includes a variety of small mammals, birds, reptiles and insects, and it also takes centipedes and spiders (2) (3) (5) (6) (9). As well as hovering, the nankeen kestrel also hunts by swooping onto prey from a perch, and it sometimes catches insects and even birds in the air (2) (3) (6).
The nankeen kestrel is usually found alone or in breeding pairs, but larger numbers occasionally gather where there is an abundance of food, such as during plagues of mice or locusts (2). Individuals sometimes perform territorial displays that involve glides on slightly drooped wings, interspersed with burst of rapid, shallow wing beats, often with the body tilted to alternate sides to produce flashes of the dark upperparts or white underparts (2) (3).
Breeding pairs of nankeen kestrels perform aerial courtship displays, and the male also brings food to the female as part of courtship (2) (3). The breeding season of this small falcon runs from around July to February, peaking between September and December (2), and pairs often mate for life (5) (6).
The nankeen kestrel nests in a variety of locations, from tree hollows, cliff ledges and urban buildings to the old stick nest of another bird (2) (3) (6). This species has even been known to nest below ground in sink-holes and mine shafts (2) (3). Except when it uses an old stick nest, the nankeen kestrel generally lays its eggs in a simple depression or scrape (3) (6), sometimes adding bits of bark or rotting wood (2).
The clutch size of the nankeen kestrel varies from one to six eggs, with three to five being more usual (2) (3). The eggs hatch after 26 to 29 days and the young kestrels leave the nest at 28 to 35 days old (2), although they remain dependent on the adults for up to 2 more months (3). The female nankeen kestrel performs most of the incubation of the eggs, while the male brings most of the food to the nest (6). The nankeen kestrel usually raises only one brood each year (6), and the young reach sexual maturity at about a year old (3).