The lanner falcon feeds mainly on small to medium-sized birds, ranging from larks up to the size of ducks and guineafowl, and sometimes takes domestic poultry and even other falcons (2) (3) (9). Hunting often takes place where prey congregates, such as at waterholes or colonial nesting sites, or at grass fires, where up to 20 lanner falcons may gather to feed (2) (3). Small mammals, such as rodents and bats, may also be taken, along with insects, reptiles, occasionally carrion, and even spiders and scorpions in deserts (2) (3) (10). The lanner falcon usually, though not always, hunts during the day, chasing or seizing prey in the air or sometimes from the ground, and occasionally stealing food from other birds of prey (2) (3) (5). Food is sometimes cached to be eaten later (2) (3), and lanner falcon pairs often hunt co-operatively, with one bird flushing out prey for the other to catch (3) (11) (12). Some lanner falcons have even learned to follow human hunters, taking prey that they flush (2) (3).
The breeding season of the lanner falcon varies with location (2) (3). Breeding pairs perform acrobatic aerial displays during courtship (3) (5), and build nests on cliffs or rocky outcrops, in quarries, on buildings or on the ground, or use the abandoned nests of other large birds, often in a tree or on top of an electricity pylon (2) (3) (12). The female lays between two and five eggs, which are incubated for 30 to 35 days. The young fledge at around 35 to 47 days but are dependent on the adult birds for up to a further three months (2) (3). Lanner falcons are thought to breed from about two to three years old (3).