the bulbuls are generally monogamous. one unusual exception is the yellow-whiskered greenbul which at least over part of its range appears to be polygamous and engage in a lekking system. some species also have alloparenting arrangements, where non-breeders, usually the young from earlier clutches, help raise the young of a dominant breeding pair. up to five purple-pink eggs are laid in an open tree nests and incubated by the female. incubation usually lasts between 11–14 days, and chicks fledge after 12–16 days.